Internet Engineering Task Force (IETF) R. Danyliw
Request for Comments: 7970 CERT
Obsoletes: 5070, 6685 November 2016
Category: Standards Track
ISSN: 2070-1721
The Incident Object Description Exchange Format Version 2
Abstract
The Incident Object Description Exchange Format (IODEF) defines a
data representation for security incident reports and indicators
commonly exchanged by operational security teams for mitigation and
watch and warning. This document describes an updated information
model for the IODEF and provides an associated data model specified
with the XML schema. This new information and data model obsoletes
RFCs 5070 and 6685.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7970.
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Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Contributions published or made publicly available before November
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material may not have granted the IETF Trust the right to allow
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Without obtaining an adequate license from the person(s) controlling
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outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6
1.2. Notations . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3. About the IODEF Data Model . . . . . . . . . . . . . . . 7
1.4. Changes from RFC 5070 . . . . . . . . . . . . . . . . . . 7
2. IODEF Data Types . . . . . . . . . . . . . . . . . . . . . . 9
2.1. Integers . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2. Real Numbers . . . . . . . . . . . . . . . . . . . . . . 9
2.3. Characters and Strings . . . . . . . . . . . . . . . . . 9
2.4. Multilingual Strings . . . . . . . . . . . . . . . . . . 9
2.5. Binary Strings . . . . . . . . . . . . . . . . . . . . . 10
2.5.1. Base64 Bytes . . . . . . . . . . . . . . . . . . . . 10
2.5.2. Hexadecimal Bytes . . . . . . . . . . . . . . . . . . 11
2.6. Enumerated Types . . . . . . . . . . . . . . . . . . . . 11
2.7. Date-Time String . . . . . . . . . . . . . . . . . . . . 11
2.8. Timezone String . . . . . . . . . . . . . . . . . . . . . 11
2.9. Port Lists . . . . . . . . . . . . . . . . . . . . . . . 11
2.10. Postal Address . . . . . . . . . . . . . . . . . . . . . 12
2.11. Telephone Number . . . . . . . . . . . . . . . . . . . . 12
2.12. Email String . . . . . . . . . . . . . . . . . . . . . . 12
2.13. Uniform Resource Locator Strings . . . . . . . . . . . . 12
2.14. Identifiers and Identifier References . . . . . . . . . . 12
2.15. Software . . . . . . . . . . . . . . . . . . . . . . . . 13
2.15.1. SoftwareReference Class . . . . . . . . . . . . . . 14
2.16. Extension . . . . . . . . . . . . . . . . . . . . . . . . 15
3. The IODEF Information Model . . . . . . . . . . . . . . . . . 18
3.1. IODEF-Document Class . . . . . . . . . . . . . . . . . . 18
3.2. Incident Class . . . . . . . . . . . . . . . . . . . . . 20
3.3. Common Attributes . . . . . . . . . . . . . . . . . . . . 23
3.3.1. restriction Attribute . . . . . . . . . . . . . . . . 23
3.3.2. observable-id Attribute . . . . . . . . . . . . . . . 25
3.4. IncidentID Class . . . . . . . . . . . . . . . . . . . . 25
3.5. AlternativeID Class . . . . . . . . . . . . . . . . . . . 26
3.6. RelatedActivity Class . . . . . . . . . . . . . . . . . . 27
3.7. ThreatActor Class . . . . . . . . . . . . . . . . . . . . 28
3.8. Campaign Class . . . . . . . . . . . . . . . . . . . . . 29
3.9. Contact Class . . . . . . . . . . . . . . . . . . . . . . 30
3.9.1. RegistryHandle Class . . . . . . . . . . . . . . . . 34
3.9.2. PostalAddress Class . . . . . . . . . . . . . . . . . 35
3.9.3. Email Class . . . . . . . . . . . . . . . . . . . . . 36
3.9.4. Telephone Class . . . . . . . . . . . . . . . . . . . 37
3.10. Discovery Class . . . . . . . . . . . . . . . . . . . . . 38
3.10.1. DetectionPattern Class . . . . . . . . . . . . . . . 40
3.11. Method Class . . . . . . . . . . . . . . . . . . . . . . 41
3.11.1. Reference Class . . . . . . . . . . . . . . . . . . 42
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3.12. Assessment Class . . . . . . . . . . . . . . . . . . . . 43
3.12.1. SystemImpact Class . . . . . . . . . . . . . . . . . 45
3.12.2. BusinessImpact Class . . . . . . . . . . . . . . . . 48
3.12.3. TimeImpact Class . . . . . . . . . . . . . . . . . . 50
3.12.4. MonetaryImpact Class . . . . . . . . . . . . . . . . 52
3.12.5. Confidence Class . . . . . . . . . . . . . . . . . . 53
3.13. History Class . . . . . . . . . . . . . . . . . . . . . . 54
3.13.1. HistoryItem Class . . . . . . . . . . . . . . . . . 54
3.14. EventData Class . . . . . . . . . . . . . . . . . . . . . 57
3.14.1. Relating the Incident and EventData Classes . . . . 59
3.14.2. Recursive Definition of EventData . . . . . . . . . 59
3.15. Expectation Class . . . . . . . . . . . . . . . . . . . . 60
3.16. Flow Class . . . . . . . . . . . . . . . . . . . . . . . 63
3.17. System Class . . . . . . . . . . . . . . . . . . . . . . 64
3.18. Node Class . . . . . . . . . . . . . . . . . . . . . . . 67
3.18.1. Address Class . . . . . . . . . . . . . . . . . . . 68
3.18.2. NodeRole Class . . . . . . . . . . . . . . . . . . . 69
3.18.3. Counter Class . . . . . . . . . . . . . . . . . . . 73
3.19. DomainData Class . . . . . . . . . . . . . . . . . . . . 75
3.19.1. Nameservers Class . . . . . . . . . . . . . . . . . 77
3.19.2. DomainContacts Class . . . . . . . . . . . . . . . . 78
3.20. Service Class . . . . . . . . . . . . . . . . . . . . . . 79
3.20.1. ServiceName Class . . . . . . . . . . . . . . . . . 80
3.20.2. ApplicationHeader Class . . . . . . . . . . . . . . 81
3.21. EmailData Class . . . . . . . . . . . . . . . . . . . . . 82
3.22. Record Class . . . . . . . . . . . . . . . . . . . . . . 83
3.22.1. RecordData Class . . . . . . . . . . . . . . . . . . 84
3.22.2. RecordPattern Class . . . . . . . . . . . . . . . . 85
3.23. WindowsRegistryKeysModified Class . . . . . . . . . . . . 87
3.23.1. Key Class . . . . . . . . . . . . . . . . . . . . . 88
3.24. CertificateData Class . . . . . . . . . . . . . . . . . . 89
3.24.1. Certificate Class . . . . . . . . . . . . . . . . . 90
3.25. FileData Class . . . . . . . . . . . . . . . . . . . . . 90
3.25.1. File Class . . . . . . . . . . . . . . . . . . . . . 91
3.26. HashData Class . . . . . . . . . . . . . . . . . . . . . 92
3.26.1. Hash Class . . . . . . . . . . . . . . . . . . . . . 94
3.26.2. FuzzyHash Class . . . . . . . . . . . . . . . . . . 95
3.27. SignatureData Class . . . . . . . . . . . . . . . . . . . 95
3.28. IndicatorData Class . . . . . . . . . . . . . . . . . . . 96
3.29. Indicator Class . . . . . . . . . . . . . . . . . . . . . 96
3.29.1. IndicatorID Class . . . . . . . . . . . . . . . . . 99
3.29.2. AlternativeIndicatorID Class . . . . . . . . . . . . 100
3.29.3. Observable Class . . . . . . . . . . . . . . . . . . 101
3.29.4. IndicatorExpression Class . . . . . . . . . . . . . 106
3.29.5. Expressions with IndicatorExpression . . . . . . . . 108
3.29.6. ObservableReference Class . . . . . . . . . . . . . 110
3.29.7. IndicatorReference Class . . . . . . . . . . . . . . 110
3.29.8. AttackPhase Class . . . . . . . . . . . . . . . . . 111
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4. Processing Considerations . . . . . . . . . . . . . . . . . . 112
4.1. Encoding . . . . . . . . . . . . . . . . . . . . . . . . 112
4.2. IODEF Namespace . . . . . . . . . . . . . . . . . . . . . 112
4.3. Validation . . . . . . . . . . . . . . . . . . . . . . . 112
4.4. Incompatibilities with v1 . . . . . . . . . . . . . . . . 113
5. Extending the IODEF . . . . . . . . . . . . . . . . . . . . . 114
5.1. Extending the Enumerated Values of Attributes . . . . . . 114
5.1.1. Private Extension of Enumerated Values . . . . . . . 114
5.1.2. Public Extension of Enumerated Values . . . . . . . . 115
5.2. Extending Classes . . . . . . . . . . . . . . . . . . . . 115
5.3. Deconflicting Private Extensions . . . . . . . . . . . . 117
6. Internationalization Issues . . . . . . . . . . . . . . . . . 118
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.1. Minimal Example . . . . . . . . . . . . . . . . . . . . . 119
7.2. Indicators from a Campaign . . . . . . . . . . . . . . . 120
8. The IODEF Data Model (XML Schema) . . . . . . . . . . . . . . 121
9. Security Considerations . . . . . . . . . . . . . . . . . . . 161
9.1. Security . . . . . . . . . . . . . . . . . . . . . . . . 161
9.2. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 162
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 163
10.1. Namespace and Schema . . . . . . . . . . . . . . . . . . 163
10.2. Enumerated Value Registries . . . . . . . . . . . . . . 163
10.3. Expert Review of IODEF-Related XML Registry Entries . . 166
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 167
11.1. Normative References . . . . . . . . . . . . . . . . . . 167
11.2. Informative References . . . . . . . . . . . . . . . . . 170
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 171
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 172
1. Introduction
Organizations require help from other parties to mitigate malicious
activity targeting their network and to gain insight into potential
threats. This coordination might entail working with an ISP to
filter attack traffic, contacting a remote site to take down a
botnet, or sharing watch lists of known malicious indicators in a
consortium.
The Incident Object Description Exchange Format (IODEF) is a format
for representing computer security information commonly exchanged
between Computer Security Incident Response Teams (CSIRTs) or other
operational security teams. It provides an XML representation for
conveying:
o indicators to characterize a threat;
o security incident reports to document attacks against an
organization;
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o response activity taken or that could be taken in response to an
incident; and
o metadata so that these various classes of information can be
exchanged among parties.
The purpose of the IODEF is to enhance the operational capabilities
of CSIRTs. Adoption of the IODEF will improve the ability of a CSIRT
to resolve security incidents; understand threats; and coordinate
response activities and proactive mitigations by simplifying
collaboration and data sharing with its partners. This structured
format provided by the IODEF allows for:
o machine-to-machine exchange of incident and indicator data;
o automated processing of this data whereby allowing more rapid
execution of appropriate courses of action; and
o the development of an ecosystem of interoperable tools enabling
security operations.
Sharing and coordinating with other organizations is not strictly a
technical problem. There are numerous procedural, cultural, legal,
and trust-related barriers to overcome. The IODEF does not attempt
to address them directly. However, operational implementations of
the IODEF will need to consider these challenges.
Section 1 provides the background for the IODEF. Sections 3 and 8
specify the IODEF information and data model, respectively. The data
types used in this document are described in Section 2. Processing
considerations, extending the specification, internationalization,
and security issues are covered in Sections 4, 5, 6, and 9,
respectively. Examples are listed in Section 7.
1.1. Terminology
The key words "MUST," "MUST NOT," "REQUIRED," "SHALL," "SHALL NOT,"
"SHOULD," "SHOULD NOT," "RECOMMENDED," "MAY," and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
1.2. Notations
The IODEF is specified as an Extensible Markup Language (XML)
[W3C.XML] schema [W3C.SCHEMA]. The normative IODEF data model is
found in the XML schema in Section 8. To aid in the understanding of
the data elements, Section 3 also depicts the underlying information
model using Unified Modeling Language (UML). This abstract
presentation of the IODEF is not normative.
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For clarity in this document, the term "XML document" will be used
when referring generically to any instance of an XML document. The
term "IODEF document" will be used to refer to an XML document
conforming to the IODEF specification. The terms "schema" will be
used to refer to Section 8 of this document. The terms "data model"
and "schema" will be used interchangeably. The terms "class" and
"element" will be used to reference either the corresponding data
element in the UML-based information or XML schema-based data models,
respectively.
1.3. About the IODEF Data Model
A number of considerations were made in the design of the IODEF data
model.
o The data model found in this document is an evolution of the one
previously specified in [RFC5070]. New fields were added to
represent additional information. [RFC5070] was developed
primarily to represent incident reports. This document builds
upon it by adding support for indicators and revising it to
reflect the current challenges faced by CSIRTs. An attempt was
made to preserve backward compatibility, but this was not possible
in all cases. See Section 4.4. This document obsoletes
[RFC5070].
o The IODEF is a transport format. Therefore, the data model may
not be the optimal archival or in-memory processing format.
o The IODEF is intended to be a framework to convey only commonly
exchanged information. It ensures that there are mechanisms for
extensibility to support organization-specific information and
techniques to reference information kept outside of the data
model.
o Not all commonly exchanged information has a well-defined format
or taxonomy. The IODEF attempts to strike a balance between
enforcing sufficient structure to allow automated processing and
supporting free-form content that enables maximum flexibility.
o The IODEF fits into a broader ecosystem of standards and
conventions. An attempt was made to harmonize the data model with
this context.
1.4. Changes from RFC 5070
A detailed list of additions made to the data model in [RFC5070] are
enumerated in this section. See Section 4.4 for a list of
incompatible changes.
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o Updated the data types (Section 2) to improve
internationalization, clarify ambiguity, and ensure consistency in
extensions.
o Added the observable-id attribute (Section 3.3.2) and
IndicatorData class (Section 3.28) to represent indicators.
o Added the private-enum-name and private-enum-id attributes to the
IODEF-Document class (Section 3.1) to disambiguate private
extensions.
o Updated the Incident class (Section 3.2) to represent additional
timing and workflow information.
o Added the ThreatActor (Section 3.7) and Campaign (Section 3.8)
classes to represent attack attribution information.
o Updated the Contact class (Section 3.9) and its children to
improve internationalization and represent additional information
about an entity.
o Updated the Method class (Section 3.11) to improve extensibility
through externally referenced resources.
o Added the Discovery class (Section 3.10) to describe how an
incident was discovered.
o Updated the Assessment class (Section 3.12) to enable more
descriptive characterizations of the impact of an incident.
o Updated the HistoryItem (Section 3.13.1) and Expectation
(Section 3.15) classes to support a reference to a course of
action.
o Updated the EventData class (Section 3.14) with additional
metadata added to the Incident class.
o Updated the System class (Section 3.17) with additional metadata.
o Updated the Counter class (Section 3.18.3) to support additional
rate metrics.
o Added DomainData (Section 3.19), EmailData (Section 3.21),
WindowsRegistryKeysModified (Section 3.23), CertificateData
(Section 3.24), and FileData (Section 3.25) classes to improve the
description of an incident and support this data as indicators.
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o Added the SignatureData (Section 3.27) and HashData (Section 3.26)
classes to represent digital signatures and hashes.
o Added support for public enumerated attribute extensions using
IANA registries (Section 5.1.2).
o Updated numerous enumerated attributes for completeness.
2. IODEF Data Types
The IODEF uses a number of simple and complex types. This section
describes these data types.
2.1. Integers
An integer is represented in the information model by the INTEGER
data type. Integer data MUST be encoded in Base 10.
The INTEGER data type is implemented in the data model as an
"xs:integer" type per Section 3.3.13 of [W3C.SCHEMA.DTYPES].
2.2. Real Numbers
A real (floating-point) number is represented in the information
model by the REAL data type. Real data MUST be encoded in Base 10.
The REAL data type is implemented in the data model as an "xs:float"
type per Section 3.2.4 of [W3C.SCHEMA.DTYPES].
2.3. Characters and Strings
A single character is represented in the information model by the
CHARACTER data type. A string is represented by the STRING data
type. Special characters MUST be encoded using entity references.
See Section 4.1.
The CHARACTER and STRING data types are implemented in the data model
as an "xs:string" type per Section 3.2.1 of [W3C.SCHEMA.DTYPES].
2.4. Multilingual Strings
A string that needs to be represented in a human-readable language
different than the default encoding of the document is represented in
the information model by the ML_STRING data type.
The ML_STRING data type is implemented in the data model as the
"iodef:MLStringType" type. This type extends the "xs:string" to
include two attributes.
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+------------------------+
| iodef:MLStringType |
+------------------------+
| xs:string |
| |
| ENUM xml:lang |
| STRING translation-id |
+------------------------+
Figure 1: The iodef:MLStringType Type
The content of the class is a character string of type "xs:string"
whose language MAY be specified by the xml:lang attribute.
The attributes of the iodef:MLStringType type are:
xml:lang
Optional. ENUM. A language identifier per Section 2.12 of
[W3C.XML] whose values and format are described in [RFC5646]. The
interpretation of this code is described in Section 6.
translation-id
Optional. STRING. An identifier to relate other instances of
this class with the same parent as translations of this text. The
scope of this identifier is limited to all of the direct, peer
child classes of a given parent class.
Using this class enables representing translations of the same text
in multiple languages. Each translation is a distinct instance of
this class with a common parent. A group of classes each with a
translated instance of text is related by setting a common identifier
in the translation-id attribute. The language of a given class is
set by the xml:lang attribute. See Section 6 for more details on
representing translations of free-form text.
2.5. Binary Strings
Binary octets can be represented with two encodings.
2.5.1. Base64 Bytes
A binary octet encoded with base64 is represented in the information
model by the BYTE data type. A sequence of these octets is of the
BYTE[] data type.
The BYTE and BYTE[] data types are implemented in the data model as
an "xs:base64Binary" type per Section 3.2.16 of [W3C.SCHEMA.DTYPES].
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2.5.2. Hexadecimal Bytes
A binary octet encoded as a character tuple consistent of two
hexadecimal digits is represented in the information model by the
HEXBIN data type. A sequence of these octets is of the HEXBIN[] data
type.
The HEXBIN and HEXBIN[] data types are implemented in the data model
as an "xs:hexBinary" type per Section 3.2.15 of [W3C.SCHEMA.DTYPES].
2.6. Enumerated Types
An enumerated type is represented in the information model by the
ENUM data type. It is an ordered list of acceptable string values.
Each value has a representative keyword. Within the data model, the
enumerated type keywords are used as attribute values.
The ENUM data type is implemented in the data model as values of an
"xs:NMTOKEN" type per Section 3.3.4 of [W3C.SCHEMA.DTYPES].
2.7. Date-Time String
A date-time string that describes a particular instant in time is
represented in the information model by the DATETIME data type.
Ranges are not supported.
The DATETIME data type is implemented in the data model as an
"xs:dateTime" type per Section 3.2.7 of [W3C.SCHEMA.DTYPES].
2.8. Timezone String
A timezone offset from UTC is represented in the information model by
the TIMEZONE data type. It is formatted according to the following
regular expression: "Z|[\+\-](0[0-9]|1[0-4]):[0-5][0-9]".
The TIMEZONE data type is implemented in the data model as an
"iodef:TimezoneType" type.
2.9. Port Lists
A list of network ports is represented in the information model by
the PORTLIST data type. A PORTLIST consists of a comma-separated
list of numbers and ranges (N-M means ports N through M, inclusive).
It is formatted according to the following regular expression:
"\d+(\-\d+)?(,\d+(\-\d+)?)*". For example,
"2,5-15,30,32,40-50,55-60".
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The PORTLIST data type is implemented in the data model as an
"iodef:PortlistType" type.
2.10. Postal Address
A postal address is represented in the information model by the
POSTAL data type. The format of the POSTAL data type is documented
in Section 2.23 of [RFC4519] as a free-form multi-line string
separated by the "$" character.
The POSTAL data type is implemented in the data model as an
"iodef:MLStringType" type.
2.11. Telephone Number
A telephone number is represented in the information model by the
PHONE data type. The format of the PHONE data type is documented in
[E.164].
The PHONE data type is implemented in the data model as an
"xs:string" type per Section 3.2.1 of [W3C.SCHEMA.DTYPES].
2.12. Email String
An email address is represented in the information model by the EMAIL
data type. The format of the EMAIL data type is documented in
Section 3.4.1 of [RFC5322] and Section 3.3 of [RFC6531].
The EMAIL data type is implemented in the data model as an
"xs:string" type per Section 3.2.1 of [W3C.SCHEMA.DTYPES].
2.13. Uniform Resource Locator Strings
A uniform resource locator (URL) is represented in the information
model by the URL data type. The format of the URL data type is
documented in [RFC3986].
The URL data type is implemented as an "xs:anyURI" type per
Section 3.2.17 of [W3C.SCHEMA.DTYPES].
2.14. Identifiers and Identifier References
An identifier unique to the IODEF document is represented in the
information model by the ID data type. A reference to this
identifier is represented by the IDREF data type.
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The ID and IDREF data types are implemented in the model as "xs:ID"
and "xs:IDREF" types per Sections 3.3.8 and 3.3.9 of
[W3C.SCHEMA.DTYPES].
2.15. Software
A particular version of software is represented in the information
model by the SOFTWARE data type. This software can be described by
using a reference, a URL, or with free-form text.
The SOFTWARE data type is implemented in the data model as the
"iodef:SoftwareType" type.
+--------------------+
| iodef:SoftwareType |
+--------------------+
| |<>--{0..1}--[ SoftwareReference ]
| |<>--{0..*}--[ URL ]
| |<>--{0..*}--[ Description ]
+--------------------+
Figure 2: The SoftwareType Type
The aggregate classes of the SoftwareType type are:
SoftwareReference
Zero or one. Reference to a software application. See
Section 2.15.1.
URL
Zero or more. URL. A URL to a resource describing the software.
Description
Zero or more. ML_STRING. A free-form text description of the
software.
At least one of these classes MUST be present.
The iodef:SoftwareType type has no attributes.
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2.15.1. SoftwareReference Class
The SoftwareReference class is a reference to a particular version of
software.
+----------------------+
| SoftwareReference |
+----------------------+
| xs:any |
| |
| ENUM spec-name |
| STRING ext-spec-name |
| ENUM dtype |
| STRING ext-dtype |
+----------------------+
Figure 3: The SoftwareReference Class
The element content varies according to the value of the spec-name
attribute. It is defined in the data model as "xs:any" per
[W3C.SCHEMA].
The attributes of the SoftwareReference class are:
spec-name
Required. ENUM. Identifies the format and semantics of the
element body of this class. Formal standards and specifications
can be referenced as well as a free-form text description with a
user-provided data type. These values are maintained in the
"SoftwareReference-spec-id" IANA registry per Section 10.2
1. custom. The element content is free-form and of the data type
specified by the dtype attribute. If this value is selected,
then the dtype attribute MUST be set.
2. cpe. The element content describes a Common Platform
Enumeration (CPE) entry per [NIST.CPE].
3. swid. The element content describes a software identification
(SWID) tag per [ISO19770].
4. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
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ext-spec-name
Optional. STRING. A means by which to extend the spec-name
attribute. See Section 5.1.1.
dtype
Optional. ENUM. The data type of the element content. The
permitted values for this attribute are shown below. The default
value is "string". These values are maintained in the
"SoftwareReference-dtype" IANA registry per Section 10.2.
1. bytes. The element content is of type HEXBIN.
2. integer. The element content is of type INTEGER.
3. real. The element content is of type REAL.
4. string. The element content is of type STRING.
5. xml. The element content is XML. See Section 5.2.
6. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-dtype
Optional. STRING. A means by which to extend the dtype
attribute. See Section 5.1.1.
2.16. Extension
Information not otherwise represented in the IODEF can be added using
the EXTENSION data type. This data type is a generic extension
mechanism.
The EXTENSION data type is implemented in the data model as the
"iodef:ExtensionType" type.
The data type of an EXTENSION is described by the dtype attribute.
For simple information, atomic data types (e.g., integers, strings)
are supported. Their semantics are further described by the meaning
and formatid attributes. Encapsulating XML documents conforming to
another schema is also supported. A detailed discussion of extending
the schema can be found in Section 5. Additional coordination may be
required to ensure that a recipient of a document using this type can
parse and process it.
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+------------------------+
| iodef:ExtensionType |
+------------------------+
| xs:any |
| |
| STRING name |
| ENUM dtype |
| STRING ext-dtype |
| STRING meaning |
| STRING formatid |
| ENUM restriction |
| STRING ext-restriction |
| ID observable-id |
+------------------------+
Figure 4: The iodef:ExtensionType Type
The element content of this type is the extension being added to the
data model. This content is defined in the data model as "xs:any"
per [W3C.SCHEMA].
The attributes of the iodef:ExtensionType type are:
name
Optional. STRING. A free-form name of the field or data element.
dtype
Required. ENUM. The data type of the element content. The
default value is "string". These values are maintained in the
"ExtensionType-dtype" IANA registry per Section 10.2.
1. boolean. The element content is of type BOOLEAN.
2. byte. The element content is of type BYTE.
3. bytes. The element content is of type HEXBIN.
4. character. The element content is of type CHARACTER.
5. date-time. The element content is of type DATETIME.
6. ntpstamp. Same as date-time.
7. integer. The element content is of type INTEGER.
8. portlist. The element content is of type PORTLIST.
9. real. The element content is of type REAL.
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10. string. The element content is of type STRING.
11. file. The element content is a base64-encoded binary file
encoded as a BYTE[] type.
12. path. The element content is a file-system path encoded as a
STRING type.
13. frame. The element content is a Layer 2 frame encoded as a
HEXBIN type.
14. packet. The element content is a Layer 3 packet encoded as a
HEXBIN type.
15. ipv4-packet. The element content is an IPv4 packet encoded
as a HEXBIN type.
16. ipv6-packet. The element content is an IPv6 packet encoded
as a HEXBIN type.
17. url. The element content is of type URL.
18. csv. The element content is a comma-separated value (CSV)
list per Section 2 of [RFC4180] encoded as a STRING type.
19. winreg. The element content is a Microsoft Windows registry
key encoded as a STRING type.
20. xml. The element content is XML. See Section 5.2.
21. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-dtype
Optional. STRING. A means by which to extend the dtype
attribute. See Section 5.1.1.
meaning
Optional. STRING. A free-form text description of the element
content.
formatid
Optional. STRING. An identifier referencing the format or
semantics of the element content.
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restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
observable-id
Optional. ID. See Section 3.3.2.
3. The IODEF Information Model
The specifics of the IODEF information model are discussed in this
section. Each class and its relationships with the other classes is
described. When necessary, clarifications are made about translating
this information model to the schema in Section 8.
3.1. IODEF-Document Class
The IODEF-Document class is the top level class in the IODEF data
model. All IODEF documents are an instance of this class.
+--------------------------+
| IODEF-Document |
+--------------------------+
| STRING version |<>--{1..*}--[ Incident ]
| ENUM xml:lang |<>--{0..*}--[ AdditionalData ]
| STRING format-id |
| STRING private-enum-name |
| STRING private-enum-id |
+--------------------------+
Figure 5: The IODEF-Document Class
The aggregate classes of the IODEF-Document class are:
Incident
One or more. The information related to a single incident. See
Section 3.2.
AdditionalData
Zero or more. EXTENSION. Mechanism by which to extend the data
model.
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The attributes of the IODEF-Document class are:
version
Required. STRING. The IODEF specification version number to
which this IODEF document conforms. The value of this attribute
MUST be "2.00".
xml:lang
Optional. ENUM. A language identifier per Section 2.12 of
[W3C.XML] whose values and form are described in [RFC5646]. The
interpretation of this code is described in Section 6.
format-id
Optional. STRING. A free-form string to convey processing
instructions to the recipient of the document. Its semantics must
be negotiated out of band.
private-enum-name
Optional. STRING. A globally unique identifier for the CSIRT
generating the document to deconflict private extensions used in
the document. The fully qualified domain name (FQDN) associated
with the CSIRT MUST be used as the identifier. See Section 5.3.
private-enum-id
Optional. STRING. An organizationally unique identifier for an
extension used in the document. If this attribute is set, the
private-enum-name MUST also be set. See Section 5.3.
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3.2. Incident Class
The Incident class describes commonly exchanged information when
reporting or sharing derived analysis from security incidents.
+-------------------------+
| Incident |
+-------------------------+
| ENUM purpose |<>----------[ IncidentID ]
| STRING ext-purpose |<>--{0..1}--[ AlternativeID ]
| ENUM status |<>--{0..*}--[ RelatedActivity ]
| STRING ext-status |<>--{0..1}--[ DetectTime ]
| ENUM xml:lang |<>--{0..1}--[ StartTime ]
| ENUM restriction |<>--{0..1}--[ EndTime ]
| STRING ext-restriction |<>--{0..1}--{ RecoveryTime ]
| ID observable-id |<>--{0..1}--[ ReportTime ]
| |<>----------[ GenerationTime ]
| |<>--{0..*}--[ Description ]
| |<>--{0..*} [ Discovery ]
| |<>--{0..*}--[ Assessment ]
| |<>--{0..*}--[ Method ]
| |<>--{1..*}--[ Contact ]
| |<>--{0..*}--[ EventData ]
| |<>--{0..1}--[ IndicatorData ]
| |<>--{0..1}--[ History ]
| |<>--{0..*}--[ AdditionalData ]
+-------------------------+
Figure 6: The Incident Class
The aggregate classes of the Incident class are:
IncidentID
One. An incident tracking number assigned to this incident by the
CSIRT that generated the IODEF document. See Section 3.4.
AlternativeID
Zero or one. The incident tracking numbers used by other CSIRTs
to refer to the incident described in the document. See
Section 3.5.
RelatedActivity
Zero or more. Related activity and attribution of this activity.
See Section 3.6.
DetectTime
Zero or one. DATETIME. The time the incident was first detected.
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StartTime
Zero or one. DATETIME. The time the incident started.
EndTime
Zero or one. DATETIME. The time the incident ended.
RecoveryTime
Zero or one. DATETIME. The time the site recovered from the
incident.
ReportTime
Zero or one. DATETIME. The time the incident was reported.
GenerationTime
One. DATETIME. The time the content in this Incident class was
generated.
Description
Zero or more. ML_STRING. A free-form text description of the
incident.
Discovery
Zero or more. The means by which this incident was detected. See
Section 3.10.
Assessment
Zero or more. A characterization of the impact of the incident.
See Section 3.12.
Method
Zero or more. The techniques used by the threat actor in the
incident. See Section 3.11.
Contact
One or more. Contact information for the parties involved in the
incident. See Section 3.9.
EventData
Zero or more. Description of the events comprising the incident.
See Section 3.14.
IndicatorData
Zero or one. Indicators from the analysis of an incident. See
Section 3.28.
History
Zero or one. A log of significant events or actions that occurred
during the course of handling the incident. See Section 3.13.
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AdditionalData
Zero or more. EXTENSION. Mechanism by which to extend the data
model.
The attributes of the Incident class are:
purpose
Required. ENUM. The purpose attribute describes the rationale
for documenting the information in this class. It is closely
related to the Expectation class (Section 3.15). These values are
maintained in the "Incident-purpose" IANA registry per
Section 10.2. This attribute is defined as an enumerated list:
1. traceback. The incident was sent for trace-back purposes.
2. mitigation. The incident was sent to request aid in
mitigating the described activity.
3. reporting. The incident was sent to comply with reporting
requirements.
4. watch. The incident was sent to convey indicators that should
be monitored.
5. other. The incident was sent for purposes specified in the
Expectation class.
6. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-purpose
Optional. STRING. A means by which to extend the purpose
attribute. See Section 5.1.1.
status
Optional. ENUM. The status attribute conveys the state in a
workflow where the incident is currently found. These values are
maintained in the "Incident-status" IANA registry per
Section 10.2. This attribute is defined as an enumerated list:
1. new. The incident is newly reported, and no action has been
taken.
2. in-progress. The incident is under investigation.
3. forwarded. The incident has been forwarded to another party
for handling.
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4. resolved. The investigation into the activity in this
incident has concluded.
5. future. The described activity has not yet been detected.
6. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-status
Optional. STRING. A means by which to extend the status
attribute. See Section 5.1.1.
xml:lang
Optional. ENUM. A language identifier per Section 2.12 of
[W3C.XML] whose values and form are described in [RFC5646]. The
interpretation of this code is described in Section 6.
restriction
Optional. ENUM. See Section 3.3.1. The default value is
"private".
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
observable-id
Optional. ID. See Section 3.3.2.
3.3. Common Attributes
There are a number of recurring attributes used in the information
model. They are documented in this section.
3.3.1. restriction Attribute
The restriction attribute indicates the disclosure guidelines to
which the sender expects the recipient to adhere for the information
represented in this class and its children. This guideline provides
no security since there are no technical means to ensure that the
recipient of the document handles the information as the sender
requested.
The value of this attribute is logically inherited by the children of
this class. That is to say, the disclosure rules applied to this
class also apply to its children.
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It is possible to set a granular disclosure policy, since all of the
high-level classes (i.e., children of the Incident class) have a
restriction attribute. Therefore, a child can override the
guidelines of a parent class, be it to restrict or relax the
disclosure rules (e.g., a child has a weaker policy than an ancestor;
or an ancestor has a weak policy, and the children selectively apply
more rigid controls). The implicit value of the restriction
attribute for a class that did not specify one can be found in the
closest ancestor that did specify a value.
This attribute is defined as an enumerated value with a default value
of "private". Note that the default value of the restriction
attribute is only defined in the context of the Incident class. In
other classes where this attribute is used, no default is specified.
These values are maintained in the "Restriction" IANA registry per
Section 10.2.
1. public. The information can be freely distributed without
restriction.
2. partner. The information may be shared within a closed
community of peers, partners, or affected parties, but cannot be
openly published.
3. need-to-know. The information may be shared only within the
organization with individuals that have a need to know.
4. private. The information may not be shared.
5. default. The information can be shared according to an
information disclosure policy pre-arranged by the communicating
parties.
6. white. Same as 'public'.
7. green. Same as 'partner'.
8. amber. Same as 'need-to-know'.
9. red. Same as 'private'.
10. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
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3.3.2. observable-id Attribute
The observable-id attribute tags information in the document as an
observable so that it can be referenced later in the description of
an indicator. The value of this attribute is a unique identifier in
the scope of the document. It is used by the ObservableReference
class to enumerate observables when defining an indicator with the
IndicatorData class.
3.4. IncidentID Class
The IncidentID class represents a tracking number that is unique in
the context of the CSIRT. It serves as an identifier for an incident
or a document identifier when sharing indicators. This identifier
would serve as an index into a CSIRT's incident handling or knowledge
management system.
The combination of the name attribute and the string in the element
content MUST be a globally unique identifier describing the activity.
Documents generated by a given CSIRT MUST NOT reuse the same value
unless they are referencing the same incident.
+------------------------+
| IncidentID |
+------------------------+
| STRING |
| |
| STRING name |
| STRING instance |
| ENUM restriction |
| STRING ext-restriction |
+------------------------+
Figure 7: The IncidentID Class
The content of the class is an incident identifier of type STRING.
The attributes of the IncidentID class are:
name
Required. STRING. An identifier describing the CSIRT that
created the document. In order to have a globally unique CSIRT
name, the fully qualified domain name associated with the CSIRT
MUST be used.
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instance
Optional. STRING. An identifier referencing a subset of the
named incident.
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
3.5. AlternativeID Class
The AlternativeID class lists the tracking numbers used by CSIRTs,
other than the one generating the document, to refer to the identical
activity described in the IODEF document. A tracking number listed
as an AlternativeID references the same incident detected by another
CSIRT. The tracking numbers of the CSIRT that generated the IODEF
document must never be considered an AlternativeID.
+------------------------+
| AlternativeID |
+------------------------+
| ENUM restriction |<>--{1..*}--[ IncidentID ]
| STRING ext-restriction |
+------------------------+
Figure 8: The AlternativeID Class
The aggregate class of the AlternativeID class is:
IncidentID
One or more. The tracking number of another CSIRT. See
Section 3.4.
The attributes of the AlternativeID class are:
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
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3.6. RelatedActivity Class
The RelatedActivity class relates the information described in the
rest of the document to previously observed incidents or activity and
allows attribution to a specific actor or campaign.
+------------------------+
| RelatedActivity |
+------------------------+
| ENUM restriction |<>--{0..*}--[ IncidentID ]
| STRING ext-restriction |<>--{0..*}--[ URL ]
| |<>--{0..*}--[ ThreatActor ]
| |<>--{0..*}--[ Campaign ]
| |<>--{0..*}--[ IndicatorID ]
| |<>--{0..1}--[ Confidence ]
| |<>--{0..*}--[ Description ]
| |<>--{0..*}--[ AdditionalData ]
+------------------------+
Figure 9: The RelatedActivity Class
The aggregate classes of the RelatedActivity class are:
IncidentID
Zero or more. The tracking number of a related incident. See
Section 3.4.
URL
Zero or more. URL. A URL to activity related to this incident.
ThreatActor
Zero or more. The threat actor to whom the incident activity is
attributed. See Section 3.7.
Campaign
Zero or more. The campaign of a given threat actor to whom the
described activity is attributed. See Section 3.8.
IndicatorID
Zero or more. A reference to a related indicator. See
Section 3.4.
Confidence
Zero or one. An estimate of the confidence in attributing this
RelatedActivity to the events described in the document. See
Section 3.12.5.
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Description
Zero or more. ML_STRING. A description of how these
relationships were derived.
AdditionalData
Zero or more. EXTENSION. A mechanism by which to extend the data
model.
The RelatedActivity class MUST have at least one instance of any of
the following child classes: IncidentID, URL, ThreatActor, Campaign,
Description, or AdditionalData.
The attributes of the RelatedActivity class are:
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
3.7. ThreatActor Class
The ThreatActor class describes a threat actor.
+------------------------+
| ThreatActor |
+------------------------+
| ENUM restriction |<>--{0..*}--[ ThreatActorID ]
| STRING ext-restriction |<>--{0..*}--[ URL ]
| |<>--{0..*}--[ Description ]
| |<>--{0..*}--[ AdditionalData ]
+------------------------+
Figure 10: The ThreatActor Class
The aggregate classes of the ThreatActor class are:
ThreatActorID
Zero or more. STRING. An identifier for the threat actor.
URL
Zero or more. URL. A URL to a reference describing the threat
actor.
Description
Zero or more. ML_STRING. A description of the threat actor.
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AdditionalData
Zero or more. EXTENSION. A mechanism by which to extend the data
model.
The ThreatActor class MUST have at least one instance of a child
class.
The attributes of the ThreatActor class are:
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
3.8. Campaign Class
The Campaign class describes a campaign of attacks by a threat actor.
+------------------------+
| Campaign |
+------------------------+
| ENUM restriction |<>--{0..*}--[ CampaignID ]
| STRING ext-restriction |<>--{0..*}--[ URL ]
| |<>--{0..*}--[ Description ]
| |<>--{0..*}--[ AdditionalData ]
+------------------------+
Figure 11: The Campaign Class
The aggregate classes of the Campaign class are:
CampaignID
Zero or more. STRING. An identifier for the campaign.
URL
Zero or more. URL. A URL to a reference describing the campaign.
Description
Zero or more. ML_STRING. A description of the campaign.
AdditionalData
Zero or more. EXTENSION. A mechanism by which to extend the data
model.
The Campaign class MUST have at least one instance of a child class.
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The attributes of the Campaign class are:
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
3.9. Contact Class
The Contact class describes contact information for organizations and
personnel involved in the incident. This class allows for the naming
of the involved party, specifying contact information for them, and
identifying their role in the incident.
People and organizations are treated interchangeably as contacts; one
can be associated with the other using the recursive definition of
the class (the Contact class is aggregated into the Contact class).
The type attribute disambiguates the type of contact information
being provided.
The recursive definition of Contact provides a way to relate
information without requiring the explicit use of identifiers or
duplication of data. A complete point of contact is derived by a
particular traversal from the root Contact class to the leaf Contact
class. Each child Contact class logically inherits contact
information from its ancestors.
+------------------------+
| Contact |
+------------------------+
| ENUM role |<>--{0..*}--[ ContactName ]
| STRING ext-role |<>--{0..*}--[ ContactTitle ]
| ENUM type |<>--{0..*}--[ Description ]
| STRING ext-type |<>--{0..*}--[ RegistryHandle ]
| ENUM restriction |<>--{0..*}--[ PostalAddress ]
| STRING ext-restriction |<>--{0..*}--[ Email ]
| |<>--{0..*}--[ Telephone ]
| |<>--{0..1}--[ Timezone ]
| |<>--{0..*}--[ Contact ]
| |<>--{0..*}--[ AdditionalData ]
+------------------------+
Figure 12: The Contact Class
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The aggregate classes of the Contact class are:
ContactName
Zero or more. ML_STRING. The name of the contact. The contact
may either be an organization or a person. The type attribute
disambiguates the semantics.
ContactTitle
Zero or more. ML_STRING. The title for the individual named in
the ContactName.
Description
Zero or more. ML_STRING. A free-form text description of the
contact.
RegistryHandle
Zero or more. A handle name into the registry of the contact.
See Section 3.9.1.
PostalAddress
Zero or more. The postal address of the contact. See
Section 3.9.2.
Email
Zero or more. The email address of the contact. See
Section 3.9.3.
Telephone
Zero or more. The telephone number of the contact. See
Section 3.9.4.
Timezone
Zero or one. TIMEZONE. The timezone in which the contact
resides.
Contact
Zero or more. A recursive definition of the Contact class. This
definition can be used to group common data pertaining to multiple
points of contact and is especially useful when listing multiple
contacts at the same organization.
AdditionalData
Zero or more. EXTENSION. A mechanism by which to extend the data
model.
At least one of the aggregate classes MUST be present in an instance
of the Contact class.
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The attributes of the Contact class are:
role
Required. ENUM. Indicates the role the contact fulfills. These
values are maintained in the "Contact-role" IANA registry per
Section 10.2.
1. creator. The entity that generates the document.
2. reporter. The entity that reported the information.
3. admin. An administrative contact or business owner for an
asset or organization.
4. tech. An entity responsible for the day-to-day management of
technical issues for an asset or organization.
5. provider. An external hosting provider for an asset.
6. user. An end-user of an asset or part of an organization.
7. billing. An entity responsible for billing issues for an
asset or organization.
8. legal. An entity responsible for legal issues related to an
asset or organization.
9. irt. An entity responsible for handling security issues for
an asset or organization.
10. abuse. An entity responsible for handling abuse originating
from an asset or organization.
11. cc. An entity that is to be kept informed about the events
related to an asset or organization.
12. cc-irt. A CSIRT or information-sharing organization
coordinating activity related to an asset or organization.
13. leo. A law enforcement organization supporting the
investigation of activity affecting an asset or organization.
14. vendor. The vendor that produces an asset.
15. vendor-support. A vendor that provides services.
16. victim. A victim in the incident.
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17. victim-notified. A victim in the incident who has been
notified.
18. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-role
Optional. STRING. A means by which to extend the role attribute.
See Section 5.1.1.
type
Required. ENUM. Indicates the type of contact being described.
This attribute is defined as an enumerated list. These values are
maintained in the "Contact-type" IANA registry per Section 10.2.
1. person. The information for this contact references an
individual.
2. organization. The information for this contact references an
organization.
3. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.1.
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
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3.9.1. RegistryHandle Class
The RegistryHandle class represents a handle into an Internet
registry or community-specific database.
+---------------------+
| RegistryHandle |
+---------------------+
| STRING |
| |
| ENUM registry |
| STRING ext-registry |
+---------------------+
Figure 13: The RegistryHandle Class
The content of the class is a handle into a registry of type STRING.
The attributes of the RegistryHandle class are:
registry
Required. ENUM. The database to which the handle belongs. These
values are maintained in the "RegistryHandle-registry" IANA
registry per Section 10.2. The possible values are:
1. internic. Internet Network Information Center
2. apnic. Asia Pacific Network Information Center
3. arin. American Registry for Internet Numbers
4. lacnic. Latin American and Caribbean Internet Addresses
Registry
5. ripe. Reseaux IP Europeens
6. afrinic. African Network Information Center
7. local. A database local to the CSIRT
8. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-registry
Optional. STRING. A means by which to extend the registry
attribute. See Section 5.1.1.
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3.9.2. PostalAddress Class
The PostalAddress class specifies a postal address and associated
annotation.
+--------------------+
| PostalAddress |
+--------------------+
| ENUM type |<>----------[ PAddress ]
| STRING ext-type |<>--{0..*}--[ Description ]
+--------------------+
Figure 14: The PostalAddress Class
The aggregate classes of the PostalAddress class are:
PAddress
One. POSTAL. A postal address.
Description
Zero or more. ML_STRING. A free-form text description of the
address.
The attributes of the PostalAddress class are:
type
Optional. ENUM. Categorizes the type of address described in the
PAddress class. These values are maintained in the
"PostalAddress-type" IANA registry per Section 10.2.
1. street. An address describing a physical location.
2. mailing. An address to which correspondence should be sent.
3. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.1.
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3.9.3. Email Class
The Email class specifies an email address and associated annotation.
+--------------------+
| Email |
+--------------------+
| ENUM type |<>----------[ EmailTo ]
| STRING ext-type |<>--{0..*}--[ Description ]
+--------------------+
Figure 15: The Email Class
The aggregate classes of the Email class are:
EmailTo
One. EMAIL. An email address.
Description
Zero or more. ML_STRING. A free-form text description of the
email address.
The attributes of the Email class are:
type
Optional. ENUM. Categorizes the type of email address described
in the EmailTo class. These values are maintained in the "Email-
type" IANA registry per Section 10.2.
1. direct. An email address of an individual.
2. hotline. An email address regularly monitored for operational
purposes.
3. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.1.
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3.9.4. Telephone Class
The Telephone class describes a telephone number and associated
annotation.
+--------------------+
| Telephone |
+--------------------+
| ENUM type |<>----------[ TelephoneNumber ]
| STRING ext-type |<>--{0..*}--[ Description ]
+--------------------+
Figure 16: The Telephone Class
The aggregate classes of the Telephone class are:
TelephoneNumber
One. PHONE. A telephone number.
Description
Zero or more. ML_STRING. A free-form text description of the
phone number.
The attributes of the Telephone class are:
type
Optional. ENUM. Categorizes the type of telephone number
described in the TelephoneNumber class. These values are
maintained in the "Telephone-type" IANA registry per Section 10.2.
1. wired. A number of a wire-line (land-line) phone.
2. mobile. A number of a mobile phone.
3. fax. A number to a fax machine.
4. hotline. A number to a regularly monitored operational
hotline.
5. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.1.
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3.10. Discovery Class
The Discovery class describes how an incident was detected.
+------------------------+
| Discovery |
+------------------------+
| ENUM source |<>--{0..*}--[ Description ]
| STRING ext-source |<>--{0..*}--[ Contact ]
| ENUM restriction |<>--{0..*}--[ DetectionPattern ]
| STRING ext-restriction |
+------------------------+
Figure 17: The Discovery Class
The aggregate classes of the Discovery class are:
Description
Zero or more. ML_STRING. A free-form text description of how
this incident was detected.
Contact
Zero or more. Contact information for the party that discovered
the incident. See Section 3.9.
DetectionPattern
Zero or more. Describes an application-specific configuration
that detected the incident. See Section 3.10.1.
The attributes of the Discovery class are:
source
Optional. ENUM. Categorizes the techniques used to discover the
incident. These values are partially derived from Table 3-1 of
[NIST800.61rev2]. These values are maintained in the "Discovery-
source" IANA registry per Section 10.2.
1. nidps. Network Intrusion Detection or Prevention System.
2. hips. Host-based Intrusion Prevention System.
3. siem. Security Information and Event Management System.
4. av. Antivirus or antispam software.
5. third-party-monitoring. Contracted third-party monitoring
service.
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6. incident. The activity was discovered while investigating an
unrelated incident.
7. os-log. Operating system logs.
8. application-log. Application logs.
9. device-log. Network device logs.
10. network-flow. Network flow analysis.
11. passive-dns. Passive DNS analysis.
12. investigation. Manual investigation initiated based on
notification of a new vulnerability or exploit.
13. audit. Security audit.
14. internal-notification. A party within the organization
reported the activity.
15. external-notification. A party outside of the organization
reported the activity.
16. leo. A law enforcement organization notified the victim
organization.
17. partner. A customer or business partner reported the
activity to the victim organization.
18. actor. The threat actor directly or indirectly reported this
activity to the victim organization.
19. unknown. Unknown detection approach.
20. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-source
Optional. STRING. A means by which to extend the source
attribute. See Section 5.1.1.
restriction
Optional. ENUM. See Section 3.3.1.
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ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
3.10.1. DetectionPattern Class
The DetectionPattern class describes a configuration or signature
that can be used by an Intrusion Detection System (IDS) / Intrusion
Prevention System (IPS), SIEM, antivirus, endpoint protection,
network analysis, malware analysis, or host forensics tool to
identify a particular phenomenon. This class requires the
identification of the target application and allows the configuration
to be described in either free form or machine-readable form.
+------------------------+
| DetectionPattern |
+------------------------+
| ENUM restriction |<>----------[ Application ]
| STRING ext-restriction |<>--{0..*}--[ Description ]
| ID observable-id |<>--{0..*}--[ DetectionConfiguration ]
+------------------------+
Figure 18: The DetectionPattern Class
The aggregate classes of the DetectionPattern class are:
Application
One. SOFTWARE. The application for which the
DetectionConfiguration or Description is being provided.
Description
Zero or more. ML_STRING. A free-form text description of how to
use the information provided in the Application or
DetectionConfiguration classes.
DetectionConfiguration
Zero or more. STRING. A machine-consumable configuration to find
a pattern of activity.
An instance of either the Description or DetectionConfiguration class
MUST be present.
The attributes of the DetectionPattern class are:
restriction
Optional. ENUM. See Section 3.3.1.
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ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
observable-id
Optional. ID. See Section 3.3.2.
3.11. Method Class
The Method class describes the tactics, techniques, procedures, or
weakness used by the threat actor in an incident. This class
consists of both a list of references describing the attack methods
and weaknesses and a free-form text description.
+------------------------+
| Method |
+------------------------+
| ENUM restriction |<>--{0..*}--[ Reference ]
| STRING ext-restriction |<>--{0..*}--[ Description ]
| |<>--{0..*}--[ sci:AttackPattern ]
| |<>--{0..*}--[ sci:Vulnerability ]
| |<>--{0..*}--[ sci:Weakness ]
| |<>--{0..*}--[ AdditionalData ]
+------------------------+
Figure 19: The Method Class
The aggregate classes of the Method class are:
Reference
Zero or more. A reference to a vulnerability, malware sample,
advisory, or analysis of an attack technique. See Section 3.11.1.
Description
Zero or more. ML_STRING. A free-form text description of
techniques, tactics, or procedures used by the threat actor.
sci:AttackPattern
Zero or more. A reference to a pattern of attack or exploitation
per [RFC7203].
sci:Vulnerability
Zero or more. A reference to a vulnerability per [RFC7203].
sci:Weakness
Zero or more. A reference to the exploited weakness per
[RFC7203].
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AdditionalData
Zero or more. EXTENSION. A mechanism by which to extend the data
model.
An instance of one of these children MUST be present.
The attributes of the Method class are:
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
3.11.1. Reference Class
The Reference class is an external reference to relevant information
such as a vulnerability, IDS alert, malware sample, advisory, or
attack technique.
+-------------------------+
| Reference |
+-------------------------+
| ID observable-id |<>--{0..1}--[ enum:ReferenceName ]
| |<>--{0..*}--[ URL ]
| |<>--{0..*}--[ Description ]
+-------------------------+
Figure 20: The Reference Class
The aggregate classes of the Reference class are:
enum:ReferenceName
Zero or one. Reference identifier per [RFC7495].
URL
Zero or more. URL. A URL to a reference.
Description
Zero or more. ML_STRING. A free-form text description of this
reference.
At least one of these classes MUST be present.
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The attribute of the Reference class is:
observable-id
Optional. ID. See Section 3.3.2.
3.12. Assessment Class
The Assessment class describes the repercussions of the incident to
the victim.
+-------------------------+
| Assessment |
+-------------------------+
| ENUM occurrence |<>--{0..*}--[ IncidentCategory ]
| ENUM restriction |<>--{0..*}--[ SystemImpact ]
| STRING ext-restriction |<>--{0..*}--[ BusinessImpact ]
| ID observable-id |<>--{0..*}--[ TimeImpact ]
| |<>--{0..*}--[ MonetaryImpact ]
| |<>--{0..*}--[ IntendedImpact ]
| |<>--{0..*}--[ Counter ]
| |<>--{0..*}--[ MitigatingFactor ]
| |<>--{0..*}--[ Cause ]
| |<>--{0..1}--[ Confidence ]
| |<>--{0..*}--[ AdditionalData ]
+-------------------------+
Figure 21: The Assessment Class
The aggregate classes of the Assessment class are:
IncidentCategory
Zero or more. ML_STRING. A free-form text description
categorizing the type of incident.
SystemImpact
Zero or more. A technical characterization of the impact of the
incident activity on the victim's enterprise. See Section 3.12.1.
BusinessImpact
Zero or more. Impact of the incident activity on the business
functions of the victim organization. See Section 3.12.2.
TimeImpact
Zero or more. A characterization of the victim organization due
to the incident activity as a function of time. See
Section 3.12.3.
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MonetaryImpact
Zero or more. The financial loss due to the incident activity.
See Section 3.12.4.
IntendedImpact
Zero or more. The intended outcome to the victim sought by the
threat actor. Defined identically to the BusinessImpact defined
in Section 3.12.2 but describes intent rather than the realized
impact.
Counter
Zero or more. A counter with which to summarize the magnitude of
the activity. See Section 3.18.3.
MitigatingFactor
Zero or more. ML_STRING. A description of a mitigating factor
relative to the impact on the victim organization.
Cause
Zero or more. ML_STRING. A description of an underlying cause of
the impact.
Confidence
Zero or one. An estimate of confidence in the impact assessment.
See Section 3.12.5.
AdditionalData
Zero or more. EXTENSION. A mechanism by which to extend the data
model.
At least one instance of the possible five impact classes (i.e.,
SystemImpact, BusinessImpact, TimeImpact, MonetaryImpact, or
IntendedImpact) MUST be present.
The attributes of the Assessment class are:
occurrence
Optional. ENUM. Specifies whether the assessment is describing
actual or potential outcomes.
1. actual. This assessment describes activity that has occurred.
2. potential. This assessment describes potential activity that
might occur.
restriction
Optional. ENUM. See Section 3.3.1.
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ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
observable-id
Optional. ID. See Section 3.3.2.
3.12.1. SystemImpact Class
The SystemImpact class describes the technical impact of the incident
to the systems on the network.
+-----------------------+
| SystemImpact |
+-----------------------+
| ENUM severity |<>--{0..*}--[ Description ]
| ENUM completion |
| ENUM type |
| STRING ext-type |
+-----------------------+
Figure 22: The SystemImpact Class
The aggregate class of the SystemImpact class is:
Description
Zero or more. ML_STRING. A free-form text description of the
impact to the system.
The attributes of the SystemImpact class are:
severity
Optional. ENUM. An estimate of the relative severity of the
activity. The permitted values are shown below. There is no
default value.
1. low. Low severity
2. medium. Medium severity
3. high. High severity
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completion
Optional. ENUM. An indication whether the described activity was
successful. The permitted values are shown below. There is no
default value.
1. failed. The attempted activity was not successful.
2. succeeded. The attempted activity succeeded.
type
Required. ENUM. Classifies the impact. The permitted values are
shown below. The default value is "unknown". These values are
maintained in the "SystemImpact-type" IANA registry per
Section 10.2.
1. takeover-account. Control was taken of a given account.
2. takeover-service. Control was taken of a given service.
3. takeover-system. Control was taken of a given system.
4. cps-manipulation. A cyber-physical system was manipulated.
5. cps-damage. A cyber-physical system was damaged.
6. availability-data. Access to particular data was degraded or
denied.
7. availability-account. Access to an account was degraded or
denied.
8. availability-service. Access to a service was degraded or
denied.
9. availability-system. Access to a system was degraded or
denied.
10. damaged-system. Hardware on a system was irreparably
damaged.
11. damaged-data. Data on a system was deleted.
12. breach-proprietary. Sensitive or proprietary information was
accessed or exfiltrated.
13. breach-privacy. Personally identifiable information was
accessed or exfiltrated.
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14. breach-credential. Credential information was accessed or
exfiltrated.
15. breach-configuration. System configuration or data inventory
was access or exfiltrated.
16. integrity-data. Data on the system was modified.
17. integrity-configuration. Application or system configuration
was modified.
18. integrity-hardware. Firmware of a hardware component was
modified.
19. traffic-redirection. Network traffic on the system was
redirected
20. monitoring-traffic. Network traffic emerging from a host or
enclave was monitored.
21. monitoring-host. System activity (e.g., running processes,
keystrokes) were monitored.
22. policy. Activity violated the system owner's acceptable use
policy.
23. unknown. The impact is unknown.
24. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.1.
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3.12.2. BusinessImpact Class
The BusinessImpact class describes and characterizes the degree to
which the function of the organization was impacted by the incident.
+-------------------------+
| BusinessImpact |
+-------------------------+
| ENUM severity |<>--{0..*}--[ Description ]
| STRING ext-severity |
| ENUM type |
| STRING ext-type |
+-------------------------+
Figure 23: The BusinessImpact Class
The aggregate class of the BusinessImpact class is:
Description
Zero or more. ML_STRING. A free-form text description of the
impact to the organization.
The attributes of the BusinessImpact class are:
severity
Optional. ENUM. Characterizes the severity of the incident on
business functions. The permitted values are shown below. They
were derived from Table 3-2 of [NIST800.61rev2]. The default
value is "unknown". These values are maintained in the
"BusinessImpact-severity" IANA registry per Section 10.2.
1. none. No effect to the organization's ability to provide all
services to all users.
2. low. Minimal effect as the organization can still provide all
critical services to all users but has lost efficiency.
3. medium. The organization has lost the ability to provide a
critical service to a subset of system users.
4. high. The organization is no longer able to provide some
critical services to any users.
5. unknown. The impact is not known.
6. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
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ext-severity
Optional. STRING. A means by which to extend the severity
attribute. See Section 5.1.1.
type
Required. ENUM. Characterizes the effect this incident had on
the business. The permitted values are shown below. The default
value is "unknown". These values are maintained in the
"BusinessImpact-type" IANA registry per Section 10.2.
1. breach-proprietary. Sensitive or proprietary information was
accessed or exfiltrated.
2. breach-privacy. Personally identifiable information was
accessed or exfiltrated.
3. breach-credential. Credential information was accessed or
exfiltrated.
4. loss-of-integrity. Sensitive or proprietary information was
changed or deleted.
5. loss-of-service. Service delivery was disrupted.
6. theft-financial. Money was stolen.
7. theft-service. Services were misappropriated.
8. degraded-reputation. The reputation of the organization's
brand was diminished.
9. asset-damage. A cyber-physical system was damaged.
10. asset-manipulation. A cyber-physical system was manipulated.
11. legal. The incident resulted in legal or regulatory action.
12. extortion. The incident resulted in actors extorting the
victim organization.
13. unknown. The impact is unknown.
14. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
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ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.1.
3.12.3. TimeImpact Class
The TimeImpact class describes the impact of the incident on an
organization as a function of time. It provides a way to convey down
time and recovery time.
+---------------------+
| TimeImpact |
+---------------------+
| REAL |
| |
| ENUM severity |
| ENUM metric |
| STRING ext-metric |
| ENUM duration |
| STRING ext-duration |
+---------------------+
Figure 24: The TimeImpact Class
The content of the class is of type REAL and specifies an amount of
time. The duration attribute provides units for this content, and
the metric attribute explains what this content is measuring.
The attributes of the TimeImpact class are:
severity
Optional. ENUM. An estimate of the relative severity of the
activity. The permitted values are shown below. There is no
default value.
1. low. Low severity
2. medium. Medium severity
3. high. High severity
metric
Required. ENUM. Defines the meaning of the value in the element
content. These values are maintained in the "TimeImpact-metric"
IANA registry per Section 10.2.
1. labor. Total staff time to recovery from the activity (e.g.,
2 employees working 4 hours each would be 8 hours).
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2. elapsed. Elapsed time from the beginning of the recovery to
its completion (i.e., wall-clock time).
3. downtime. Duration of time for which some provided service(s)
was not available.
4. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-metric
Optional. STRING. A means by which to extend the metric
attribute. See Section 5.1.1.
duration
Optional. ENUM. Defines the unit of time for the value in the
element content. The default value is "hour". These values are
maintained in the "TimeImpact-duration" IANA registry per
Section 10.2.
1. second. The unit of the element content is seconds.
2. minute. The unit of the element content is minutes.
3. hour. The unit of the element content is hours.
4. day. The unit of the element content is days.
5. month. The unit of the element content is months.
6. quarter. The unit of the element content is quarters.
7. year. The unit of the element content is years.
8. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-duration
Optional. STRING. A means by which to extend the duration
attribute. See Section 5.1.1.
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3.12.4. MonetaryImpact Class
The MonetaryImpact class describes the financial impact of the
activity on an organization. For example, this impact may consider
losses due to the cost of the investigation or recovery, diminished
productivity of the staff, or a tarnished reputation that will affect
future opportunities.
+------------------+
| MonetaryImpact |
+------------------+
| REAL |
| |
| ENUM severity |
| STRING currency |
+------------------+
Figure 25: The MonetaryImpact Class
The content of the class is of type REAL and specifies a quantity of
money. The currency attribute defines the currency of this value.
The attributes of the MonetaryImpact class are:
severity
Optional. ENUM. An estimate of the relative severity of the
activity. The permitted values are shown below. There is no
default value.
1. low. Low severity
2. medium. Medium severity
3. high. High severity
currency
Optional. STRING. Defines the currency in which the value in the
element content is expressed. The permitted values are defined in
"Codes for the representation of currencies" [ISO4217]. There is
no default value.
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3.12.5. Confidence Class
The Confidence class represents an estimate of the validity and
accuracy of data expressed in the document. This estimate can be
expressed as a category or a numeric calculation.
+-------------------+
| Confidence |
+-------------------+
| REAL |
| |
| ENUM rating |
| STRING ext-rating |
+-------------------+
Figure 26: The Confidence Class
The content of the class is of type REAL and specifies a numerical
assessment in the confidence of the data when the value of the rating
attribute is "numeric". Otherwise, this element MUST be empty.
The attributes of the Confidence class are:
rating
Required. ENUM. A qualitative assessment of confidence. These
values are maintained in the "Confidence-rating" IANA registry per
Section 10.2
1. low. Low confidence.
2. medium. Medium confidence.
3. high. High confidence.
4. numeric. The element content contains a number that conveys
the confidence of the data. The semantics of this number is
outside the scope of this specification.
5. unknown. The confidence rating value is not known.
6. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-rating
Optional. STRING. A means by which to extend the rating
attribute. See Section 5.1.1.
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3.13. History Class
The History class is a log of the significant events or actions
performed by the involved parties during the course of handling the
incident.
The level of detail maintained in this log is left up to the
discretion of those handling the incident.
+------------------------+
| History |
+------------------------+
| ENUM restriction |<>--{1..*}--[ HistoryItem ]
| STRING ext-restriction |
+------------------------+
Figure 27: The History Class
The aggregate classes of the History class are:
HistoryItem
One or more. An entry in the history log of significant events or
actions performed by the involved parties. See Section 3.13.1.
The attributes of the History class are:
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
3.13.1. HistoryItem Class
The HistoryItem class is an entry in the History (Section 3.13) log
that documents a particular action or event that occurred in the
course of handling the incident. The details of the entry are a
free-form text description, but each can be categorized with the type
attribute.
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+-------------------------+
| HistoryItem |
+-------------------------+
| ENUM action |<>----------[ DateTime ]
| STRING ext-action |<>--{0..1}--[ IncidentID ]
| ENUM restriction |<>--{0..1}--[ Contact ]
| STRING ext-restriction |<>--{0..*}--[ Description ]
| ID observable-id |<>--{0..*}--[ DefinedCOA ]
| |<>--{0..*}--[ AdditionalData ]
+-------------------------+
Figure 28: The HistoryItem Class
The aggregate classes of the HistoryItem class are:
DateTime
One. DATETIME. A timestamp of this entry in the history log.
IncidentID
Zero or one. In a history log created by multiple parties, the
IncidentID provides a mechanism to specify which CSIRT created a
particular entry and references this organization's tracking
number. When a single organization is maintaining the log, this
class can be ignored. See Section 3.4.
Contact
Zero or one. Provides contact information for the entity that
performed the action documented in this class. See Section 3.9.
Description
Zero or more. ML_STRING. A free-form text description of the
action or event.
DefinedCOA
Zero or more. STRING. An identifier meaningful to the sender and
recipient of this document that references a course of action
(COA). This class MUST be present if the action attribute is set
to "defined-coa".
AdditionalData
Zero or more. EXTENSION. A mechanism by which to extend the data
model.
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The attributes of the HistoryItem class are:
action
Required. ENUM. Classifies a performed action or occurrence
documented in this history log entry. As activity will likely
have been instigated either through a previously conveyed
expectation or through an internal investigation, this attribute
is identical to the action attribute of the Expectation class.
The difference is only one of tense. When an action is in this
class, it has been completed. See Section 3.15.
ext-action
Optional. STRING. A means by which to extend the action
attribute. See Section 5.1.1.
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
observable-id
Optional. ID. See Section 3.3.2.
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3.14. EventData Class
The EventData class is a container class to organize data about
events that occurred during an incident.
+-------------------------+
| EventData |
+-------------------------+
| ENUM restriction |<>--{0..*}--[ Description ]
| STRING ext-restriction |<>--{0..1}--[ DetectTime ]
| ID observable-id |<>--{0..1}--[ StartTime ]
| |<>--{0..1}--[ EndTime ]
| |<>--{0..1}--[ RecoveryTime ]
| |<>--{0..1}--[ ReportTime ]
| |<>--{0..*}--[ Contact ]
| |<>--{0..*}--[ Discovery ]
| |<>--{0..1}--[ Assessment ]
| |<>--{0..*}--[ Method ]
| |<>--{0..*}--[ Flow ]
| |<>--{0..*}--[ Expectation ]
| |<>--{0..1}--[ Record ]
| |<>--{0..*}--[ EventData ]
| |<>--{0..*}--[ AdditionalData ]
+-------------------------+
Figure 29: The EventData Class
The aggregate classes of the EventData class are:
Description
Zero or more. ML_STRING. A free-form text description of the
event.
DetectTime
Zero or one. DATETIME. The time the event was detected.
StartTime
Zero or one. DATETIME. The time the event started.
EndTime
Zero or one. DATETIME. The time the event ended.
RecoveryTime
Zero or one. DATETIME. The time the site recovered from the
event.
ReportTime
Zero or one. DATETIME. The time the event was reported.
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Contact
Zero or more. Contact information for the parties involved in the
event. See Section 3.9.
Discovery
Zero or more. The means by which the event was detected. See
Section 3.10.
Assessment
Zero or one. The impact of the event on the victim and the
actions taken. See Section 3.12.
Method
Zero or more. The technique used by the threat actor in the
event. See Section 3.11.
Flow
Zero or more. A description of the systems or networks involved.
See Section 3.16.
Expectation
Zero or more. The expected action to be performed by the
recipient for the described event. See Section 3.15.
Record
Zero or one. Supportive data (e.g., log files) that provides
additional information about the event. See Section 3.22.
EventData
Zero or more. A recursive definition of the EventData class. See
Section 3.14.2 for an explanation on using this class.
AdditionalData
Zero or more. EXTENSION. An extension mechanism for data not
explicitly represented in the data model.
At least one of the aggregate classes MUST be present in an instance
of the EventData class.
The attributes of the EventData class are:
restriction
Optional. ENUM. See Section 3.3.1. The default value is
"default".
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
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observable-id
Optional. ID. See Section 3.3.2.
3.14.1. Relating the Incident and EventData Classes
There is substantial overlap in the child classes aggregated in the
Incident and EventData classes. Nevertheless, the semantics of these
classes are quite different. The Incident class provides summary
information about the entire incident, while the EventData class
provides information about the individual events comprising the
incident. In the common case, the EventData class will provide more
specific information for the general description provided in the
Incident class. However, in the case where the summarized
information in the Incident class conflicts with the detailed
information in an EventData class, the more specific EventData class
MUST supersede the more generic information provided in the Incident
class.
3.14.2. Recursive Definition of EventData
The EventData class is a container for the properties of an event in
an incident. These properties include: the hosts involved, impact of
the incident activity on the hosts, forensic logs, etc. The
recursive definition of EventData allows for the grouping of related
information with common properties. This approach eliminates the
need for explicit identifiers to relate information or duplicate it.
Instead, the relative depth (nesting) of a class is used to group
(relate) information.
For example, consider a case where two hosts experience different
impacts during an incident. However, these two hosts have common
contact information. A depiction of how this situation would be
represented can be found in Figure 30. EventData (2) and (3) group
each of the two hosts with their unique impact. EventData (1)
describes the common Contact class these two hosts share.
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+------------------+
| EventData (1) |
+------------------+
| |<>----[ Contact ]
| |
| |<>----[ EventData (2) ]<>----[ Flow ]
| | [ ]<>----[ Assessment ]
| |
| |<>----[ EventData (3) ]<>----[ Flow ]
| | [ ]<>----[ Assessment ]
+------------------+
Figure 30: Recursion in the EventData Class
3.15. Expectation Class
The Expectation class conveys to the recipient of the IODEF document
the actions the sender is requesting.
+-------------------------+
| Expectation |
+-------------------------+
| ENUM action |<>--{0..*}--[ Description ]
| STRING ext-action |<>--{0..*}--[ DefinedCOA ]
| ENUM severity |<>--{0..1}--[ StartTime ]
| ENUM restriction |<>--{0..1}--[ EndTime ]
| STRING ext-restriction |<>--{0..1}--[ Contact ]
| ID observable-id |
+-------------------------+
Figure 31: The Expectation Class
The aggregate classes of the Expectation class are:
Description
Zero or more. ML_STRING. A free-form text description of the
desired action(s).
DefinedCOA
Zero or more. STRING. A unique identifier meaningful to the
sender and recipient of this document that references a course of
action. This class MUST be present if the action attribute is set
to "defined-coa".
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StartTime
Zero or one. DATETIME. The time at which the sender would like
the action performed. A timestamp that is earlier than the
ReportTime specified in the Incident class denotes that the sender
would like the action performed as soon as possible. The absence
of this element indicates no expectations of when the recipient
would like the action performed.
EndTime
Zero or one. DATETIME. The time by which the sender expects the
recipient to complete the action. If the recipient cannot
complete the action before EndTime, the recipient MUST NOT carry
out the action. Because of transit delays and clock drift, the
sender MUST be prepared for the recipient to have carried out the
action, even if it completes past EndTime.
Contact
Zero or one. The entity expected to perform the action. See
Section 3.9.
The attributes of the Expectation class are:
action
Optional. ENUM. Classifies the type of action requested. The
default value of "other". These values are maintained in the
"Expectation-action" IANA registry per Section 10.2.
1. nothing. No action is requested. Do nothing with the
information.
2. contact-source-site. Contact the site(s) identified as the
source of the activity.
3. contact-target-site. Contact the site(s) identified as the
target of the activity.
4. contact-sender. Contact the originator of the document.
5. investigate. Investigate the system(s) listed in the event.
6. block-host. Block traffic from the machine(s) listed as
sources in the event.
7. block-network. Block traffic from the network(s) lists as
sources in the event.
8. block-port. Block the port listed as sources in the event.
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9. rate-limit-host. Rate-limit the traffic from the machine(s)
listed as sources in the event.
10. rate-limit-network. Rate-limit the traffic from the
network(s) lists as sources in the event.
11. rate-limit-port. Rate-limit the port(s) listed as sources in
the event.
12. redirect-traffic. Redirect traffic from the intended
recipient for further analysis.
13. honeypot. Redirect traffic from systems listed in the event
to a honeypot for further analysis.
14. upgrade-software. Upgrade or patch the software or firmware
on an asset listed in the event.
15. rebuild-asset. Reinstall the operating system or
applications on an asset listed in the event.
16. harden-asset. Change the configuration of an asset listed in
the event to reduce the attack surface.
17. remediate-other. Remediate the activity in a way other than
by rate-limiting or blocking.
18. status-triage. Confirm receipt and begin triaging the
incident.
19. status-new-info. Notify the sender when new information is
received for this incident.
20. watch-and-report. Watch for the described activity or
indicators, and notify the sender when seen.
21. training. Train user to identify or mitigate the described
threat.
22. defined-coa. Perform a predefined course of action (COA).
The COA is named in the DefinedCOA class.
23. other. Perform a custom action described in the Description
class.
24. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
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ext-action
Optional. STRING. A means by which to extend the action
attribute. See Section 5.1.1.
severity
Optional. ENUM. Indicates the desired priority of the action.
This attribute is an enumerated list with no default value, and
the semantics of these relative measures are context dependent.
1. low. Low priority
2. medium. Medium priority
3. high. High priority
restriction
Optional. ENUM. See Section 3.3.1. The default value is
"default".
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
observable-id
Optional. ID. See Section 3.3.2.
3.16. Flow Class
The Flow class describes the systems and networks involved in the
incident and the relationships between them.
+------------------+
| Flow |
+------------------+
| |<>--{1..*}--[ System ]
+------------------+
Figure 32: The Flow Class
The aggregate class of the Flow class is:
System
One or More. A host or network involved in an event. See
Section 3.17.
The Flow class has no attributes.
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3.17. System Class
The System class describes a system or network involved in an event.
+------------------------+
| System |
+------------------------+
| ENUM category |<>----------[ Node ]
| STRING ext-category |<>--{0..*}--[ NodeRole ]
| STRING interface |<>--{0..*}--[ Service ]
| ENUM spoofed |<>--{0..*}--[ OperatingSystem ]
| ENUM virtual |<>--{0..*}--[ Counter ]
| ENUM ownership |<>--{0..*}--[ AssetID ]
| STRING ext-ownership |<>--{0..*}--[ Description ]
| ENUM restriction |<>--{0..*}--[ AdditionalData ]
| STRING ext-restriction |
| ID observable-id |
+------------------------+
Figure 33: The System Class
The aggregate classes of the System class are:
Node
One. A host or network involved in the incident. See
Section 3.18.
NodeRole
Zero or more. The intended purpose of the system. See
Section 3.18.2.
Service
Zero or more. A network service running on the system. See
Section 3.20.
OperatingSystem
Zero or more. SOFTWARE. The operating system running on the
system.
Counter
Zero or more. A counter with which to summarize properties of
this host or network. See Section 3.18.3.
AssetID
Zero or more. STRING. An asset identifier for the System.
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Description
Zero or more. ML_STRING. A free-form text description of the
System.
AdditionalData
Zero or more. EXTENSION. A mechanism by which to extend the data
model.
The attributes of the System class are:
category
Optional. ENUM. Classifies the role the host or network played
in the incident. These values are maintained in the "System-
category" IANA registry per Section 10.2.
1. source. The System was the source of the event.
2. target. The System was the target of the event.
3. intermediate. The System was an intermediary in the event.
4. sensor. The System was a sensor monitoring the event.
5. infrastructure. The System was an infrastructure node of the
IODEF document exchange.
6. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-category
Optional. STRING. A means by which to extend the category
attribute. See Section 5.1.1.
interface
Optional. STRING. Specifies the interface on which the event(s)
on this System originated. If the Node class specifies a network
rather than a host, this attribute has no meaning.
spoofed
Optional. ENUM. An indication of confidence in whether this
System was the true target or attacking host. The permitted
values for this attribute are shown below. The default value is
"unknown".
1. unknown. The accuracy of the category attribute value is
unknown.
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2. yes. The category attribute value is likely incorrect. In
the case of a source, the System is likely a decoy; with a
target, the System was likely not the intended victim.
3. no. The category attribute value is believed to be correct.
virtual
Optional. ENUM. Indicates whether this System is a virtual or
physical device. The default value is "unknown".
1. yes. The System is a virtual device.
2. no. The System is a physical device.
3. unknown. It is not known if the System is virtual.
ownership
Optional. ENUM. Describes the ownership of this System relative
to the victim in the incident. These values are maintained in the
"System-ownership" IANA registry per Section 10.2.
1. organization. Corporate or enterprise owned.
2. personal. Personally owned by an employee or affiliate of the
corporation or enterprise.
3. partner. Owned by a partner of the corporation or enterprise.
4. customer. Owned by a customer of the corporation or
enterprise.
5. no-relationship. Owned by an entity that has no known
relationship with the victim organization.
6. unknown. Ownership is unknown.
7. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-ownership
Optional. STRING. A means by which to extend the ownership
attribute. See Section 5.1.1.
restriction
Optional. ENUM. See Section 3.3.1.
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ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
observable-id
Optional. ID. See Section 3.3.2.
3.18. Node Class
The Node class identifies a system, asset, or network and its
location.
+---------------+
| Node |
+---------------+
| |<>--{0..*}--[ DomainData ]
| |<>--{0..*}--[ Address ]
| |<>--{0..1}--[ PostalAddress ]
| |<>--{0..*}--[ Location ]
| |<>--{0..*}--[ Counter ]
+---------------+
Figure 34: The Node Class
The aggregate classes of the Node class are:
DomainData
Zero or more. The domain (DNS) information associated with this
node. If an Address is not provided, at least one DomainData MUST
be specified. See Section 3.19.
Address
Zero or more. The hardware, network, or application address of
the node. If a DomainData is not provided, at least one Address
MUST be specified. See Section 3.18.1.
PostalAddress
Zero or one. POSTAL. The postal address of the node.
Location
Zero or more. ML_STRING. A free-form text description of the
physical location of the node. This description may provide a
more detailed description of where at the address specified by the
PostalAddress class this node is found (e.g., room number, rack
number, or slot number in a chassis).
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Counter
Zero or more. A counter with which to summarize properties of
this host or network. See Section 3.18.3.
The Node class has no attributes.
3.18.1. Address Class
The Address class represents a hardware (Layer 2), network (Layer 3),
or application (Layer 7) address.
+-------------------------+
| Address |
+-------------------------+
| STRING |
| |
| ENUM category |
| STRING ext-category |
| STRING vlan-name |
| INTEGER vlan-num |
| ID observable-id |
+-------------------------+
Figure 35: The Address Class
The content of the class is an address of type STRING whose semantics
are determined by the category attribute.
The attributes of the Address class are:
category
Required. ENUM. The type of address represented. The default
value is "ipv6-addr". These values are maintained in the
"Address-category" IANA registry per Section 10.2.
1. asn. Autonomous System Number.
2. atm. Asynchronous Transfer Mode (ATM) address.
3. e-mail. Email address, per the EMAIL data type.
4. ipv4-addr. IPv4 host address in dotted-decimal notation
(i.e., a.b.c.d).
5. ipv4-net. IPv4 network address in dotted-decimal notation,
slash, significant bits (i.e., a.b.c.d/nn).
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6. ipv4-net-masked. A sanitized IPv4 address with significant
bits per "ipv4-net" but with the character 'x' replacing any
digit(s) in the address or prefix.
7. ipv4-net-mask. IPv4 network address in dotted-decimal
notation, slash, network mask in dotted-decimal notation
(i.e., a.b.c.d/w.x.y.z).
8. ipv6-addr. IPv6 host address per Section 4 of [RFC5952].
9. ipv6-net. IPv6 network address, slash, prefix per
Section 2.3 of [RFC4291].
10. ipv6-net-masked. A sanitized IPv6 address and prefix per
"ipv6-net" but with the character 'x' replacing any
hexadecimal digit(s) in the address or digit(s) in the
prefix.
11. mac. Media Access Control (MAC) address (i.e.,
aa:bb:cc:dd:ee:ff).
12. site-uri. A URL or URI for a resource, per the URL data
type.
13. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-category
Optional. STRING. A means by which to extend the category
attribute. See Section 5.1.1.
vlan-name
Optional. STRING. The name of the Virtual LAN to which the
address belongs.
vlan-num
Optional. INTEGER. The number of the Virtual LAN to which the
address belongs.
observable-id
Optional. ID. See Section 3.3.2.
3.18.2. NodeRole Class
The NodeRole class describes the function performed by or role of a
particular system, asset, or network.
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+-----------------------+
| NodeRole |
+-----------------------+
| ENUM category |<>--{0..*}--[ Description ]
| STRING ext-category |
+-----------------------+
Figure 36: The NodeRole Class
The aggregate class of the NodeRole class is:
Description
Zero or more. ML_STRING. A free-form text description of the
role of the system.
The attributes of the NodeRole class are:
category
Required. ENUM. Function or role of a node. These values are
maintained in the "NodeRole-category" IANA registry per
Section 10.2.
1. client. Client computer.
2. client-enterprise. Client computer on the enterprise
network.
3. client-partner. Client computer on network of a partner.
4. client-remote. Client computer remotely connected to the
enterprise network.
5. client-kiosk. Client computer serving as a kiosk.
6. client-mobile. Mobile device.
7. server-internal. Server with internal services.
8. server-public. Server with public services.
9. www. WWW server.
10. mail. Mail server.
11. webmail. Web mail server.
12. messaging. Messaging server (e.g., NNTP, IRC, IM).
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13. streaming. Streaming-media server.
14. voice. Voice server (e.g., SIP, H.323).
15. file. File server.
16. ftp. FTP server.
17. p2p. Peer-to-peer node.
18. name. Name server (e.g., DNS, WINS).
19. directory. Directory server (e.g., LDAP, finger, whois).
20. credential. Credential server (e.g., domain controller,
Kerberos).
21. print. Print server.
22. application. Application server.
23. database. Database server.
24. backup. Backup server.
25. dhcp. DHCP server.
26. assessment. Assessment server (e.g., vulnerability scanner,
endpoint assessment).
27. source-control. Source code control server.
28. config-management. Configuration management server.
29. monitoring. Security monitoring server (e.g., IDS).
30. infra. Infrastructure server (e.g., router, firewall, DHCP).
31. infra-firewall. Firewall.
32. infra-router. Router.
33. infra-switch. Switch.
34. camera. Camera and video system.
35. proxy. Proxy server.
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36. remote-access. Remote access server.
37. log. Log server (e.g., syslog).
38. virtualization. Server running virtual machines.
39. pos. Point-of-sale device.
40. scada. Supervisory control and data acquisition (SCADA)
system.
41. scada-supervisory. Supervisory system for a SCADA.
42. sinkhole. Traffic sinkhole destination.
43. honeypot. Honeypot server.
44. anonymization. Anonymization server (e.g., Tor node).
45. c2-server. Malicious command and control server.
46. malware-distribution. Server that distributes malware
47. drop-server. Server to which exfiltrated content is
uploaded.
48. hop-point. Intermediary server used to get to a victim.
49. reflector. A system used in a reflector attack.
50. phishing-site. Site hosting phishing content.
51. spear-phishing-site. Site hosting spear-phishing content.
52. recruiting-site. Site to recruit.
53. fraudulent-site. Fraudulent site.
54. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-category
Optional. STRING. A means by which to extend the category
attribute. See Section 5.1.1.
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3.18.3. Counter Class
The Counter class summarizes multiple occurrences of an event or
conveys counts or rates of various features.
The complete semantics of this class are context dependent based on
the class in which it is aggregated.
+---------------------+
| Counter |
+---------------------+
| REAL |
| |
| ENUM type |
| STRING ext-type |
| ENUM unit |
| STRING ext-unit |
| STRING meaning |
| ENUM duration |
| STRING ext-duration |
+---------------------+
Figure 37: The Counter Class
The content of the class is a value of type REAL whose meaning and
units are determined by the type and duration attributes,
respectively. If the duration attribute is present, the element
content is a rate. Otherwise, it is a simple counter.
The attributes of the Counter class are:
type
Required. ENUM. Specifies the type of counter specified in the
element content. These values are maintained in the "Counter-
type" IANA registry per Section 10.2.
1. count. The Counter class value is a counter.
2. peak. The Counter class value is a peak value.
3. average. The Counter class value is an average.
4. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
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ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.1.
unit
Required. ENUM. Specifies the units of the element content.
These values are maintained in the "Counter-unit" IANA registry
per Section 10.2.
1. byte. Bytes transferred.
2. mbit. Megabits (Mbits) transferred.
3. packet. Packets.
4. flow. Network flow records.
5. session. Sessions.
6. alert. Notifications generated by another system (e.g., IDS
or SIEM system).
7. message. Messages (e.g., mail messages).
8. event. Events.
9. host. Hosts.
10. site. Site.
11. organization. Organizations.
12. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-unit
Optional. STRING. A means by which to extend the unit attribute.
See Section 5.1.1.
meaning
Optional. STRING. A free-form text description of the metric
represented by the Counter.
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duration
Optional. ENUM. If present, the Counter class represents a rate.
This attribute specifies a unit of time over which the rate whose
units are specified in the unit attribute is being conveyed. This
attribute is the denominator of the rate (where the unit attribute
specified the nominator). The possible values of this attribute
are defined in the duration attribute of Section 3.12.3
ext-duration
Optional. STRING. A means by which to extend the duration
attribute. See Section 5.1.1.
3.19. DomainData Class
The DomainData class describes a domain name and metadata associated
with this domain.
+--------------------------+
| DomainData |
+--------------------------+
| ENUM system-status |<>----------[ Name ]
| STRING ext-system-status |<>--{0..1}--[ DateDomainWasChecked ]
| ENUM domain-status |<>--{0..1}--[ RegistrationDate ]
| STRING ext-domain-status |<>--{0..1}--[ ExpirationDate ]
| ID observable-id |<>--{0..*}--[ RelatedDNS ]
| |<>--{0..*}--[ Nameservers ]
| |<>--{0..1}--[ DomainContacts ]
+--------------------------+
Figure 38: The DomainData Class
The aggregate classes of the DomainData class are:
Name
One. STRING. The domain name of a system.
DateDomainWasChecked
Zero or one. DATETIME. A timestamp of when the domain listed in
the Name class was resolved.
RegistrationDate
Zero or one. DATETIME. A timestamp of when domain listed in the
Name class was registered.
ExpirationDate
Zero or one. DATETIME. A timestamp of when the domain listed in
the Name class is set to expire.
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RelatedDNS
Zero or more. EXTENSION. Additional DNS records associated with
this domain.
Nameservers
Zero or more. The nameservers identified for the domain listed in
the Name class. See Section 3.19.1.
DomainContacts
Zero or one. Contact information for the domain listed in the
Name class supplied by the registrar or through a whois query.
The attributes of the DomainData class are:
system-status
Required. ENUM. Assesses the domain's involvement in the event.
These values are maintained in the "DomainData-system-status" IANA
registry per Section 10.2.
1. spoofed. This domain was spoofed.
2. fraudulent. This domain was operated with fraudulent
intentions.
3. innocent-hacked. This domain was compromised by a third
party.
4. innocent-hijacked. This domain was deliberately hijacked.
5. unknown. No categorization for this domain known.
6. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-system-status
Optional. STRING. A means by which to extend the system-status
attribute. See Section 5.1.1.
domain-status
Required. ENUM. Categorizes the registry status of the domain at
the time the document was generated. These values and their
associated descriptions are derived from Section 3.2.2 of
[RFC3982]. These values are maintained in the
"DomainData-domain-status" IANA registry per Section 10.2.
1. reservedDelegation. The domain is permanently inactive.
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2. assignedAndActive. The domain is in a normal state.
3. assignedAndInactive. The domain has an assigned
registration, but the delegation is inactive.
4. assignedAndOnHold. The domain is in dispute.
5. revoked. The domain is in the process of being purged from
the database.
6. transferPending. The domain is pending a change in
authority.
7. registryLock. The domain is on hold by the registry.
8. registrarLock. Same as "registryLock".
9. other. The domain has a known status, but it is not one of
the redefined enumerated values.
10. unknown. The domain has an unknown status.
11. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-domain-status
Optional. STRING. A means by which to extend the domain-status
attribute. See Section 5.1.1.
observable-id
Optional. ID. See Section 3.3.2.
3.19.1. Nameservers Class
The Nameservers class describes the nameservers associated with a
given domain.
+--------------------+
| Nameservers |
+--------------------+
| |<>----------[ Server ]
| |<>--{1..*}--[ Address ]
+--------------------+
Figure 39: The Nameservers Class
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The aggregate classes of the Nameservers class are:
Server
One. STRING. The domain name of the nameserver.
Address
One or more. The address of the nameserver. The value of the
category attribute MUST be either "ipv4-addr" or "ipv6-addr". See
Section 3.18.1.
The Nameservers class has no attributes.
3.19.2. DomainContacts Class
The DomainContacts class describes the contact information for a
given domain provided either by the registrar or through a whois
query.
This contact information can be explicitly described through a
Contact class, or a reference can be provided to a domain with
identical contact information. Either a single SameDomainContact or
one or more Contact classes MUST be present.
+--------------------+
| DomainContacts |
+--------------------+
| |<>--{0..1}--[ SameDomainContact ]
| |<>--{1..*}--[ Contact ]
+--------------------+
Figure 40: The DomainContacts Class
The aggregate classes of the DomainContacts class are:
SameDomainContact
Zero or one. STRING. A domain name already cited in this
document or through previous exchange that contains the identical
contact information as the domain name in question. The domain
contact information associated with this domain should be used
instead of an explicit definition with the Contact class.
Contact
One or more. Contact information for the domain. See
Section 3.9.
The DomainContacts class has no attributes.
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3.20. Service Class
The Service class describes a network service. The service is
described by a protocol, port, protocol header field, and application
providing or using the service.
+-------------------------+
| Service |
+-------------------------+
| INTEGER ip-protocol |<>--{0..1}--[ ServiceName ]
| ID observable-id |<>--{0..1}--[ Port ]
| |<>--{0..1}--[ Portlist ]
| |<>--{0..1}--[ ProtoCode ]
| |<>--{0..1}--[ ProtoType ]
| |<>--{0..1}--[ ProtoField ]
| |<>--{0..1}--[ ApplicationHeader ]
| |<>--{0..1}--[ EmailData ]
| |<>--{0..1}--[ Application ]
+-------------------------+
Figure 41: The Service Class
The aggregate classes of the Service class are:
ServiceName
Zero or one. A protocol name.
Port
Zero or one. INTEGER. A port number.
Portlist
Zero or one. PORTLIST. A list of port numbers.
ProtoCode
Zero or one. INTEGER. A transport-layer (Layer 4) protocol-
specific code field (e.g., ICMP code field).
ProtoType
Zero or one. INTEGER. A transport-layer (Layer 4) protocol-
specific type field (e.g., ICMP type field).
ProtoField
Zero or one. INTEGER. A transport-layer (Layer 4) protocol-
specific flag field (e.g., TCP flag field).
ApplicationHeader
Zero or one. A protocol header. See Section 3.20.2.
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EmailData
Zero or one. Headers associated with an email message. See
Section 3.21.
Application
Zero or one. SOFTWARE. The application acting as either the
client or the server for the service.
At least one of these classes MUST be present.
When a given System class with category="source" and another with
category="target" are aggregated into a single Flow class, and each
of these System classes has a Service and Portlist class, an implicit
relationship between these Portlists exists. If N ports are listed
for a System@category="source", and M ports are listed for
System@category="target", the number of ports in N must be equal to
M. Likewise, the ports MUST be listed in an identical sequence such
that the n-th port in the source corresponds to the n-th port of the
target. If N is greater than 1, a given instance of a Flow class
MUST only have a single instance of a System@category="source" and
System@category="target".
The attributes of the Service class are:
ip-protocol
Optional. INTEGER. The IANA-assigned IP protocol number per
[IANA.Protocols]. The attribute MUST be set if a Port, Portlist,
ProtoCode, ProtoType, or ProtoField class is present.
observable-id
Optional. ID. See Section 3.3.2.
3.20.1. ServiceName Class
The ServiceName class identifies an application protocol. It can be
described by referencing an IANA-registered protocol, by referencing
a URL, or with free-form text.
+--------------------+
| ServiceName |
+--------------------+
| |<>--{0..1}--[ IANAService ]
| |<>--{0..*}--[ URL ]
| |<>--{0..*}--[ Description ]
+--------------------+
Figure 42: The ServiceName Class
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The aggregate classes of the ServiceName class are:
IANAService
Zero or one. STRING. The name of the service per the "Service
Name" field of the registry [IANA.Ports].
URL
Zero or more. URL. A URL to a resource describing the service.
Description
Zero or more. ML_STRING. A free-form text description of the
service.
At least one of these classes MUST be present.
The ServiceName class has no attributes.
3.20.2. ApplicationHeader Class
The ApplicationHeader class describes arbitrary fields from a
protocol header and its corresponding value.
+--------------------------+
| ApplicationHeader |
+--------------------------+
| |<>--{1..*}--[ ApplicationHeaderField ]
+--------------------------+
Figure 43: The ApplicationHeader Class
The aggregate class of the ApplicationHeader class is:
ApplicationHeaderField
One or more. EXTENSION. A field name and value in a protocol
header. The name attribute MUST be set to the field name. The
field value MUST be set in the element content.
The ApplicationHeader class has no attributes.
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3.21. EmailData Class
The EmailData class describes headers from an email message and
cryptographic hashes and signatures applied to it.
+-------------------------+
| EmailData |
+-------------------------+
| ID observable-id |<>--{0..*}--[ EmailTo ]
| |<>--{0..1}--[ EmailFrom ]
| |<>--{0..1}--[ EmailSubject ]
| |<>--{0..1}--[ EmailX-Mailer ]
| |<>--{0..*}--[ EmailHeaderField ]
| |<>--{0..1}--[ EmailHeaders ]
| |<>--{0..1}--[ EmailBody ]
| |<>--{0..1}--[ EmailMessage ]
| |<>--{0..*}--[ HashData ]
| |<>--{0..*}--[ SignatureData ]
+-------------------------+
Figure 44: EmailData Class
The aggregate classes of the EmailData class are:
EmailTo
Zero or more. EMAIL. The value of the "To:" header field
(Section 3.6.3 of [RFC5322]) in an email.
EmailFrom
Zero or one. EMAIL. The value of the "From:" header field
(Section 3.6.2 of [RFC5322]) in an email.
EmailSubject
Zero or one. STRING. The value of the "Subject:" header field in
an email. See Section 3.6.5 of [RFC5322].
EmailX-Mailer
Zero or one. STRING. The value of the "X-Mailer:" header field
in an email.
EmailHeaderField
Zero or more. EXTENSION. The header name and value of an
arbitrary header field of the email message. The name attribute
MUST be set to the header name. The header value MUST be set in
the element body. The dtype attribute MUST be set to "string".
EmailHeaders
Zero or one. STRING. The headers of an email message.
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EmailBody
Zero or one. STRING. The body of an email message.
EmailMessage
Zero or one. STRING. The headers and body of an email message.
HashData
Zero or more. Hash(es) associated with this email message. See
Section 3.26.
SignatureData
Zero or more. Signature(s) associated with this email message.
See Section 3.27.
The attribute of the EmailData class is:
observable-id
Optional. ID. See Section 3.3.2.
3.22. Record Class
The Record class is a container class for log and audit data that
provides supportive information about the events in an incident. The
source of this data will often be the output of monitoring tools.
These logs substantiate the activity described in the document.
+------------------------+
| Record |
+------------------------+
| ENUM restriction |<>--{1..*}--[ RecordData ]
| STRING ext-restriction |
+------------------------+
Figure 45: The Record Class
The aggregate classes of the Record class are:
RecordData
One or more. Log or audit data generated by a particular tool.
Separate instances of the RecordData class SHOULD be used for each
type of log. See Section 3.22.1.
The attributes of the Record class are:
restriction
Optional. ENUM. See Section 3.3.1.
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ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
3.22.1. RecordData Class
The RecordData class describes or references log or audit data from a
given type of tool and provides a means to annotate the output.
+------------------------+
| RecordData |
+------------------------+
| ENUM restriction |<>--{0..1}--[ DateTime ]
| STRING ext-restriction |<>--{0..*}--[ Description ]
| ID observable-id |<>--{0..1}--[ Application ]
| |<>--{0..*}--[ RecordPattern ]
| |<>--{0..*}--[ RecordItem ]
| |<>--{0..*}--[ URL ]
| |<>--{0..*}--[ FileData ]
| |<>--{0..*}--
| | [ WindowsRegistryKeysModified ]
| |<>--{0..*}--[ CertificateData ]
| |<>--{0..*}--[ AdditionalData ]
+------------------------+
Figure 46: The RecordData Class
The aggregate classes of the RecordData class are:
DateTime
Zero or one. DATETIME. A timestamp of the data found in the
RecordItem or URL classes.
Description
Zero or more. ML_STRING. A free-form text description of the
data provided in the RecordItem or URL classes.
Application
Zero or one. SOFTWARE. Identifies the tool used to generate the
data in the RecordItem or URL classes.
RecordPattern
Zero or more. A search string to precisely find the relevant data
in the RecordItem or URL classes. See Section 3.22.2.
RecordItem
Zero or more. EXTENSION. Log, audit, or forensic data to support
the conclusions made during the course of analyzing the incident.
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URL
Zero or more. URL. A URL reference to a log or audit data.
FileData
Zero or one. The files involved in the incident. See
Section 3.25.
WindowsRegistryKeysModified
Zero or more. The registry keys that were involved in the
incident. See Section 3.23.
CertificateData
Zero or more. The certificates that were involved in the
incident. See Section 3.24.
AdditionalData
Zero or more. EXTENSION. An extension mechanism for data not
explicitly represented in the data model.
At least one of the following classes MUST be present: RecordItem,
URL, FileData, WindowsRegistryKeysModified, CertificateData, or
AdditionalData.
The attributes of the RecordData class are:
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
observable-id
Optional. ID. See Section 3.3.2.
3.22.2. RecordPattern Class
The RecordPattern class describes where in the log data provided or
referenced in the RecordData class relevant information can be found.
It provides a way to reference subsets of information, identified by
a pattern, in a large log file, audit trail, or forensic data.
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+-----------------------+
| RecordPattern |
+-----------------------+
| STRING |
| |
| ENUM type |
| STRING ext-type |
| INTEGER offset |
| ENUM offsetunit |
| STRING ext-offsetunit |
| INTEGER instance |
+-----------------------+
Figure 47: The RecordPattern Class
The content of the class is of type STRING and specifies a search
pattern.
The attributes of the RecordPattern class are:
type
Required. ENUM. Describes the type of pattern being specified in
the element content. The default is "regex". These values are
maintained in the "RecordPattern-type" IANA registry per
Section 10.2.
1. regex. Regular expression as defined by POSIX Extended
Regular Expressions (ERE) in Chapter 9 of [IEEE.POSIX].
2. binary. Binhex-encoded binary pattern, per the HEXBIN data
type.
3. xpath. XML Path (XPath) [W3C.XPATH].
4. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.1.
offset
Optional. INTEGER. Amount of units (determined by the offsetunit
attribute) to seek into the RecordItem data before matching the
pattern.
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offsetunit
Optional. ENUM. Describes the units of the offset attribute.
The default is "line". These values are maintained in the
"RecordPattern-offsetunit" IANA registry per Section 10.2.
1. line. Offset is a count of lines.
2. byte. Offset is a count of bytes.
3. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-offsetunit
Optional. STRING. A means by which to extend the offsetunit
attribute. See Section 5.1.1.
instance
Optional. INTEGER. Number of times to apply the specified
pattern.
3.23. WindowsRegistryKeysModified Class
The WindowsRegistryKeysModified class describes Windows operating
system registry keys and the operations that were performed on them.
This class was derived from [RFC5901].
+-----------------------------+
| WindowsRegistryKeysModified |
+-----------------------------+
| ID observable-id |<>--{1..*}--[ Key ]
+-----------------------------+
Figure 48: The WindowsRegistryKeysModified Class
The aggregate classes of the WindowsRegistryKeysModified class are:
Key
One or more. The Windows registry key. See Section 3.23.1.
The attribute of the WindowsRegistryKeysModified class is:
observable-id
Optional. ID. See Section 3.3.2.
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3.23.1. Key Class
The Key class describes a Windows operating system registry key name
and value pair, as well as the operation performed on it.
+---------------------------+
| Key |
+---------------------------+
| ENUM registryaction |<>----------[ KeyName ]
| STRING ext-registryaction |<>--{0..1}--[ KeyValue ]
| ID observable-id |
+---------------------------+
Figure 49: The Key Class
The aggregate classes of the Key class are:
KeyName
One. STRING. The name of a Windows operating system registry key
(e.g., [HKEY_LOCAL_MACHINE\Software\Test\KeyName]).
KeyValue
Zero or one. STRING. The value of the registry key identified in
the KeyName class encoded per the .reg file format [KB310516].
The attributes of the Key class are:
registryaction
Optional. ENUM. The type of action taken on the registry key.
These values are maintained in the "Key-registryaction" IANA
registry per Section 10.2.
1. add-key. Registry key added.
2. add-value. Value added to a registry key.
3. delete-key. Registry key deleted.
4. delete-value. Value deleted from a registry key.
5. modify-key. Registry key modified.
6. modify-value. Value modified in a registry key.
7. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
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ext-registryaction
Optional. STRING. A means by which to extend the registryaction
attribute. See Section 5.1.1.
observable-id
Optional. ID. See Section 3.3.2.
3.24. CertificateData Class
The CertificateData class describes X.509 certificates.
+------------------------+
| CertificateData |
+------------------------+
| ENUM restriction |<>--{1..*}--[ Certificate ]
| STRING ext-restriction |
| ID observable-id |
+------------------------+
Figure 50: The CertificateData Class
The aggregate classes of the CertificateData class are:
Certificate
One or more. A description of an X.509 certificate or certificate
chain. See Section 3.24.1.
The attributes of the CertificateData class are:
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
observable-id
Optional. ID. See Section 3.3.2.
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3.24.1. Certificate Class
The Certificate class describes a given X.509 certificate or
certificate chain.
+--------------------------+
| Certificate |
+--------------------------+
| ID observable-id |<>----------[ ds:X509Data ]
| |<>--{0..*}--[ Description ]
+--------------------------+
Figure 51: The Certificate Class
The aggregate classes of the Certificate class are:
ds:X509Data
One. A given X.509 certificate or chain. See Section 4.4.4 of
[W3C.XMLSIG].
Description
Zero or more. ML_STRING. A free-form text description explaining
the context of this certificate.
The attributes of the Certificate class are:
observable-id
Optional. ID. See Section 3.3.2.
3.25. FileData Class
The FileData class describes a file or set of files.
+------------------------+
| FileData |
+------------------------+
| ENUM restriction |<>--{1..*}--[ File ]
| STRING ext-restriction |
| ID observable-id |
+------------------------+
Figure 52: The FileData Class
The aggregate classes of the FileData class are:
File
One or more. A description of a file. See Section 3.25.1.
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The attributes of the FileData class are:
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
observable-id
Optional. ID. See Section 3.3.2.
3.25.1. File Class
The File class describes a file; its associated metadata; and
cryptographic hashes and signatures applied to it.
+-----------------------+
| File |
+-----------------------+
| ID observable-id |<>--{0..1}--[ FileName ]
| |<>--{0..1}--[ FileSize ]
| |<>--{0..1}--[ FileType ]
| |<>--{0..*}--[ URL ]
| |<>--{0..1}--[ HashData ]
| |<>--{0..1}--[ SignatureData ]
| |<>--{0..1}--[ AssociatedSoftware ]
| |<>--{0..*}--[ FileProperties ]
+-----------------------+
Figure 53: The File Class
The aggregate classes of the File class are:
FileName
Zero or one. STRING. The name of the file.
FileSize
Zero or one. INTEGER. The size of the file in bytes.
FileType
Zero or one. STRING. The type of file per the IANA "Media Types"
registry [IANA.Media]. Valid values correspond to the text in the
"Template" column (e.g., "application/pdf").
URL
Zero or more. URL. A URL reference to the file.
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HashData
Zero or one. Hash(es) associated with this file. See
Section 3.26.
SignatureData
Zero or one. Signature(s) associated with this file. See
Section 3.27.
AssociatedSoftware
Zero or one. SOFTWARE. The software application or operating
system to which this file belongs or by which it can be processed.
FileProperties
Zero or more. EXTENSION. Mechanism by which to extend the data
model to describe properties of the file.
The attributes of the File class are:
observable-id
Optional. ID. See Section 3.3.2.
3.26. HashData Class
The HashData class describes different types of hashes on a given
object (e.g., file, part of a file, email).
+--------------------------+
| HashData |
+--------------------------+
| ENUM scope |<>--{0..1}--[ HashTargetID ]
| |<>--{0..*}--[ Hash ]
| |<>--{0..*}--[ FuzzyHash ]
+--------------------------+
Figure 54: The HashData Class
The aggregate classes of the HashData class are:
HashTargetID
Zero or one. STRING. An identifier that references a subset of
the object being hashed. The semantics of this identifier are
specified by the scope attribute.
Hash
Zero or more. The hash of an object. See Section 3.26.1.
FuzzyHash
Zero or more. The fuzzy hash of an object. See Section 3.26.2.
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At least one instance of either Hash or FuzzyHash MUST be present.
The attribute of the HashData class is:
scope
Required. ENUM. Describes on which part of the object the hash
should be applied. These values are maintained in the "HashData-
scope" IANA registry per Section 10.2.
1. file-contents. A hash computed over the entire contents of a
file.
2. file-pe-section. A hash computed on a given section of a
Windows Portable Executable (PE) file. If set to this value,
the HashTargetID class MUST identify the section being hashed.
A section is identified by an ordinal number (starting at 1)
corresponding to the order in which the given section header
was defined in the Section Table of the PE file header.
3. file-pe-iat. A hash computed on the Import Address
Table (IAT) of a PE file. As IAT hashes are often tool
dependent, if this value is set, the Application class of
either the Hash or FuzzyHash classes MUST specify the tool
used to generate the hash.
4. file-pe-resource. A hash computed on a given resource in a PE
file. If set to this value, the HashTargetID class MUST
identify the resource being hashed. A resource is identified
by an ordinal number (starting at 1) corresponding to the
order in which the given resource is declared in the Resource
Directory of the Data Dictionary in the PE file header.
5. file-pdf-object. A hash computed on a given object in a
Portable Document Format (PDF) file. If set to this value,
the HashTargetID class MUST identify the object being hashed.
This object is identified by its offset in the PDF file.
6. email-hash. A hash computed over the headers and body of an
email message.
7. email-headers-hash. A hash computed over all of the headers
of an email message.
8. email-body-hash. A hash computed over the body of an email
message.
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9. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-scope
Optional. STRING. A means by which to extend the scope
attribute. See Section 5.1.1.
3.26.1. Hash Class
The Hash class describes a cryptographic hash value; the algorithm
and application used to generate it; and the canonicalization method
applied to the object being hashed.
+----------------+
| Hash |
+----------------+
| |<>----------[ ds:DigestMethod ]
| |<>----------[ ds:DigestValue ]
| |<>--{0..1}--[ ds:CanonicalizationMethod ]
| |<>--{0..1}--[ Application ]
+----------------+
Figure 55: The Hash Class
The aggregate classes of the Hash class are:
ds:DigestMethod
One. The hash algorithm used to generate the hash. See
Section 4.3.3.5 of [W3C.XMLSIG].
ds:DigestValue
One. The computed hash value. See Section 4.3.3.6 of
[W3C.XMLSIG].
ds:CanonicalizationMethod
Zero or one. The canonicalization method used on the object being
hashed. See Section 4.3.1 of [W3C.XMLSIG].
Application
Zero or one. SOFTWARE. The application used to calculate the
hash.
The HashData class has no attributes.
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3.26.2. FuzzyHash Class
The FuzzyHash class describes a fuzzy hash and the application used
to generate it.
+--------------------------+
| FuzzyHash |
+--------------------------+
| |<>--{1..*}--[ FuzzyHashValue ]
| |<>--{0..1}--[ Application ]
| |<>--{0..*}--[ AdditionalData ]
+--------------------------+
Figure 56: The FuzzyHash Class
The aggregate classes of the FuzzyHash class are:
FuzzyHashValue
One or more. EXTENSION. The computed fuzzy hash value.
Application
Zero or one. SOFTWARE. The application used to calculate the
hash.
AdditionalData
Zero or more. EXTENSION. Mechanism by which to extend the data
model.
The FuzzyData class has no attributes.
3.27. SignatureData Class
The SignatureData class describes different types of digital
signatures on an object.
+--------------------------+
| SignatureData |
+--------------------------+
| |<>--{1..*}--[ ds:Signature ]
+--------------------------+
Figure 57: The SignatureData Class
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The aggregate class of the SignatureData class is:
Signature
One or more. A given signature. See Section 4.2 of [W3C.XMLSIG].
The SignatureData class has no attributes.
3.28. IndicatorData Class
The IndicatorData class describes indicators and metadata associated
with them.
+--------------------------+
| IndicatorData |
+--------------------------+
| |<>--{1..*}--[ Indicator ]
+--------------------------+
Figure 58: The IndicatorData Class
The aggregate class of the IndicatorData class is:
Indicator
One or more. A description of an indicator. See Section 3.29.
The IndicatorData class has no attributes.
3.29. Indicator Class
The Indicator class describes an indicator. An indicator consists of
observable features and phenomenon that aid in the forensic or
proactive detection of malicious activity and associated metadata.
An indicator can be described outright by referencing or composing
previously defined indicators or by referencing observables described
in the incident report found in this document.
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+------------------------+
| Indicator |
+------------------------+
| ENUM restriction |<>----------[ IndicatorID ]
| STRING ext-restriction |<>--{0..*}--[ AlternativeIndicatorID ]
| |<>--{0..*}--[ Description ]
| |<>--{0..1}--[ StartTime ]
| |<>--{0..1}--[ EndTime ]
| |<>--{0..1}--[ Confidence ]
| |<>--{0..*}--[ Contact ]
| |<>--{0..1}--[ Observable ]
| |<>--{0..1}--[ ObservableReference ]
| |<>--{0..1}--[ IndicatorExpression ]
| |<>--{0..1}--[ IndicatorReference ]
| |<>--{0..*}--[ NodeRole ]
| |<>--{0..*}--[ AttackPhase ]
| |<>--{0..*}--[ Reference ]
| |<>--{0..*}--[ AdditionalData ]
+------------------------+
Figure 59: The Indicator Class
The aggregate classes of the Indicator class are:
IndicatorID
One. An identifier for this indicator. See Section 3.29.1.
AlternativeIndicatorID
Zero or more. An alternative identifier for this indicator. See
Section 3.29.2.
Description
Zero or more. ML_STRING. A free-form text description of the
indicator.
StartTime
Zero or one. DATETIME. A timestamp of the start of the time
period during which this indicator is valid.
EndTime
Zero or one. DATETIME. A timestamp of the end of the time period
during which this indicator is valid.
Confidence
Zero or one. An estimate of the confidence in the quality of the
indicator. See Section 3.12.5.
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Contact
Zero or more. Contact information for this indicator. See
Section 3.9.
Observable
Zero or one. An observable feature or phenomenon of this
indicator. See Section 3.29.3.
ObservableReference
Zero or one. A reference to an observable feature or phenomenon
defined elsewhere in the document. See Section 3.29.6.
IndicatorExpression
Zero or one. A composition of observables. See Section 3.29.4.
IndicatorReference
Zero or one. A reference to an indicator. See Section 3.29.7.
NodeRole
Zero or more. The role of the system in the attack should this
indicator be matched to it. See Section 3.18.2.
AttackPhase
Zero or more. The phase in an attack life cycle during which this
indicator might be seen. See Section 3.29.8.
Reference
Zero or more. A reference to additional information relevant to
this indicator. See Section 3.11.1.
AdditionalData
Zero or more. EXTENSION. Mechanism by which to extend the data
model.
The Indicator class MUST have exactly one instance of an Observable,
IndicatorExpression, ObservableReference, or IndicatorReference
class.
The StartTime and EndTime classes can be used to define an interval
during which the indicator is valid. If both classes are present,
the indicator is consider valid only during the described interval.
If neither class is provided, the indicator is considered valid
during any time interval. If only a StartTime is provided, the
indicator is valid anytime after this timestamp. If only an EndTime
is provided, the indicator is valid anytime prior to this timestamp.
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The attributes of the Indicator class are:
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
3.29.1. IndicatorID Class
The IndicatorID class identifies an indicator with a globally unique
identifier. The combination of the name and version attributes and
the element content form this identifier. Indicators generated by
given CSIRT MUST NOT reuse the same value unless they are referencing
the same indicator.
+------------------+
| IndicatorID |
+------------------+
| ID |
| |
| STRING name |
| STRING version |
+------------------+
Figure 60: The IndicatorID Class
The content of the class is of type ID and specifies an identifier
for an indicator.
The attributes of the IndicatorID class are:
name
Required. STRING. An identifier describing the CSIRT that
created the indicator. In order to have a globally unique CSIRT
name, the fully qualified domain name associated with the CSIRT
MUST be used. This format is identical to the IncidentID@name
attribute in Section 3.4.
version
Required. STRING. A version number of an indicator.
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3.29.2. AlternativeIndicatorID Class
The AlternativeIndicatorID class lists alternative identifiers for an
indicator.
+-------------------------+
| AlternativeIndicatorID |
+-------------------------+
| ENUM restriction |<>--{1..*}--[ IndicatorReference ]
| STRING ext-restriction |
+-------------------------+
Figure 61: The AlternativeIndicatorID Class
The aggregate class of the AlternativeIndicatorID class is:
IndicatorReference
One or more. A reference to an indicator. See Section 3.29.7.
The attributes of the AlternativeIndicatorID class are:
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
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3.29.3. Observable Class
The Observable class describes a feature and phenomenon that can be
observed or measured for the purposes of detecting malicious
behavior.
+------------------------+
| Observable |
+------------------------+
| ENUM restriction |<>--{0..1}--[ System ]
| STRING ext-restriction |<>--{0..1}--[ Address ]
| |<>--{0..1}--[ DomainData ]
| |<>--{0..1}--[ Service ]
| |<>--{0..1}--[ EmailData ]
| |<>--{0..1}--[ WindowsRegistryKeysModified ]
| |<>--{0..1}--[ FileData ]
| |<>--{0..1}--[ CertificateData ]
| |<>--{0..1]--[ RegistryHandle ]
| |<>--{0..1}--[ RecordData ]
| |<>--{0..1}--[ EventData ]
| |<>--{0..1}--[ Incident ]
| |<>--{0..1}--[ Expectation ]
| |<>--{0..1}--[ Reference ]
| |<>--{0..1}--[ Assessment ]
| |<>--{0..1}--[ DetectionPattern ]
| |<>--{0..1}--[ HistoryItem ]
| |<>--{0..1}--[ BulkObservable ]
| |<>--{0..*}--[ AdditionalData ]
+------------------------+
Figure 62: The Observable Class
The aggregate classes of the Observable class are:
System
Zero or one. A System observable. See Section 3.17.
Address
Zero or one. An Address observable. See Section 3.18.1.
DomainData
Zero or one. A DomainData observable. See Section 3.19.
Service
Zero or one. A Service observable. See Section 3.20.
EmailData
Zero or one. An EmailData observable. See Section 3.21.
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WindowsRegistryKeysModified
Zero or one. A WindowsRegistryKeysModified observable. See
Section 3.23.
FileData
Zero or one. A FileData observable. See Section 3.25.
CertificateData
Zero or one. A CertificateData observable. See Section 3.24.
RegistryHandle
Zero or one. A RegistryHandle observable. See Section 3.9.1.
RecordData
Zero or one. A RecordData observable. See Section 3.22.1.
EventData
Zero or one. An EventData observable. See Section 3.14.
Incident
Zero or one. An Incident observable. See Section 3.2.
Expectation
Zero or one. An Expectation observable. See Section 3.15.
Reference
Zero or one. A Reference observable. See Section 3.11.1.
Assessment
Zero or one. An Assessment observable. See Section 3.12.
DetectionPattern
Zero or one. A DetectionPattern observable. See Section 3.10.1.
HistoryItem
Zero or one. A HistoryItem observable. See Section 3.13.1.
BulkObservable
Zero or one. A bulk list of observables. See Section 3.29.3.1.
AdditionalData
Zero or more. EXTENSION. Mechanism by which to extend the data
model.
The Observable class MUST have exactly one of the possible child
classes.
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The attributes of the Observable class are:
restriction
Optional. ENUM. See Section 3.3.1.
ext-restriction
Optional. STRING. A means by which to extend the restriction
attribute. See Section 5.1.1.
3.29.3.1. BulkObservable Class
The BulkObservable class allows the enumeration of a single type of
observable without requiring each one to be encoded individually in
multiple instances of the same class.
The type attribute describes the type of observable listed in the
child BulkObservableList class. The BulkObservableFormat class
optionally provides additional metadata.
+---------------------------+
| BulkObservable |
+---------------------------+
| ENUM type |<>--{0..1}--[ BulkObservableFormat ]
| STRING ext-type |<>----------[ BulkObservableList ]
| |<>--{0..*}--[ AdditionalData ]
+---------------------------+
Figure 63: The BulkObservable Class
The aggregate classes of the BulkObservable class are:
BulkObservableFormat
Zero or one. Provides additional metadata about the observables
enumerated in the BulkObservableList class. See
Section 3.29.3.1.1.
BulkObservableList
One. STRING. A list of observables, one per line. Each line is
separated with either a LF character or CR and LF characters. The
type attribute specifies which observables will be listed.
AdditionalData
Zero or more. EXTENSION. Mechanism by which to extend the data
model.
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The attributes of the BulkObservable class are:
type
Optional. ENUM. The type of the observable listed in the child
ObservableList class. These values are maintained in the
"BulkObservable-type" IANA registry per Section 10.2.
1. asn. Autonomous System Number (per the Address@category
attribute).
2. atm. Asynchronous Transfer Mode (ATM) address (per the
Address@category attribute).
3. e-mail. Email address (per the Address@category attribute).
4. ipv4-addr. IPv4 host address in dotted-decimal notation,
e.g., 192.0.2.1 (per the Address@category attribute).
5. ipv4-net. IPv4 network address in dotted-decimal notation,
slash, significant bits, e.g., 192.0.2.0/24 (per the
Address@category attribute).
6. ipv4-net-mask. IPv4 network address in dotted-decimal
notation, slash, network mask in dotted-decimal notation,
i.e., 192.0.2.0/255.255.255.0 (per the Address@category
attribute).
7. ipv6-addr. IPv6 host address, e.g., 2001:DB8::3 (per the
Address@category attribute).
8. ipv6-net. IPv6 network address, slash, significant bits,
e.g., 2001:DB8::/32 (per the Address@category attribute).
9. ipv6-net-mask. IPv6 network address, slash, network mask
(per the Address@category attribute).
10. mac. Media Access Control (MAC) address, i.e., a:b:c:d:e:f
(per the Address@category attribute).
11. site-uri. A URL or URI for a resource (per the
Address@category attribute).
12. domain-name. A fully qualified domain name or part of a name
(e.g., fqdn.example.com, example.com).
13. domain-to-ipv4. A mapping of FQDN to IPv4 address specified
as a comma-separated list (e.g., "fqdn.example.com,
192.0.2.1").
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14. domain-to-ipv6. A mapping of FQDN to IPv6 address specified
as a comma-separated list (e.g., "fqdn.example.com,
2001:DB8::3").
15. domain-to-ipv4-timestamp. Same as domain-to-ipv4 but with a
timestamp (in the DATETIME format) of the resolution (e.g.,
"fqdn.example.com, 192.0.2.1, 2015-06-11T00:38:31-06:00").
16. domain-to-ipv6-timestamp. Same as domain-to-ipv6 but with a
timestamp (in the DATETIME format) of the resolution (e.g.,
"fqdn.example.com, 2001:DB8::3, 2015-06-11T00:38:31-06:00").
17. ipv4-port. An IPv4 address, port, and protocol tuple (e.g.,
192.0.2.1, 80, TCP). The protocol name corresponds to the
"Keyword" column in the "Assigned Internet Protocol Numbers"
registry [IANA.Protocols].
18. ipv6-port. An IPv6 address, port, and protocol tuple (e.g.,
2001:DB8::3, 80, TCP). The protocol name corresponds to the
"Keyword" column in the "Assigned Internet Protocol Numbers"
registry [IANA.Protocols].
19. windows-reg-key. A Microsoft Windows registry key.
20. file-hash. A file hash. The format of this hash is
described in the Hash class that MUST be present in a sibling
BulkObservableFormat class.
21. email-x-mailer. An X-Mailer field from an email.
22. email-subject. An email subject line.
23. http-user-agent. A User Agent field from an HTTP request
header (e.g., "Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0)
Gecko/20100101 Firefox/38.0").
24. http-request-uri. The Request URI from an HTTP request
header.
25. mutex. The name of a system mutex (mutual exclusion lock).
26. file-path. A file path (e.g., "/tmp/local/file",
"c:\windows\system32\file.sys").
27. user-name. A username.
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28. ext-value. A value used to indicate that this attribute is
extended and the actual value is provided using the
corresponding ext-* attribute. See Section 5.1.1.
ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.1.
3.29.3.1.1. BulkObservableFormat Class
The ObservableFormat class specifies metadata about the format of an
observable enumerated in a sibling BulkObservableList class.
+---------------------------+
| BulkObservableFormat |
+---------------------------+
| |<>--{0..1}--[ Hash ]
| |<>--{0..*}--[ AdditionalData ]
+---------------------------+
Figure 64: The BulkObservableFormat Class
The aggregate classes of the BulkObservableFormat class are:
Hash
Zero or one. Describes the format of a hash. See Section 3.26.1.
AdditionalData
Zero or more. EXTENSION. Mechanism by which to extend the data
model.
The BulkObservableFormat class has no attributes.
Either Hash or AdditionalData MUST be present.
3.29.4. IndicatorExpression Class
The IndicatorExpression describes an expression composed of observed
phenomenon, features, or indicators. Elements of the expression can
be described directly, reference relevant data from other parts of a
given IODEF document, or reference previously defined indicators.
All child classes of a given instance of IndicatorExpression form a
boolean algebraic expression where the operator between them is
determined by the operator attribute.
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+--------------------------+
| IndicatorExpression |
+--------------------------+
| ENUM operator |<>--{0..*}--[ IndicatorExpression ]
| STRING ext-operator |<>--{0..*}--[ Observable ]
| |<>--{0..*}--[ ObservableReference ]
| |<>--{0..*}--[ IndicatorReference ]
| |<>--{0..1}--[ Confidence ]
| |<>--{0..*}--[ AdditionalData ]
+--------------------------+
Figure 65: The IndicatorExpression Class
The aggregate classes of the IndicatorExpression class are:
IndicatorExpression
Zero or more. An expression composed of other observables or
indicators. See Section 3.29.4.
Observable
Zero or more. A description of an observable. See
Section 3.29.3.
ObservableReference
Zero or more. A reference to an observable. See Section 3.29.6.
IndicatorReference
Zero or more. A reference to an indicator. See Section 3.29.7.
Confidence
Zero or one. An estimate of the confidence in the quality of the
terms expressed in the expression. See Section 3.12.5.
AdditionalData
Zero or more. EXTENSION. Mechanism by which to extend the data
model.
The attributes of the IndicatorExpression class are:
operator
Optional. ENUM. The operator to be applied between the child
elements. See Section 3.29.5 for parsing guidance. The default
value is "and". These values are maintained in the
"IndicatorExpression-operator" IANA registry per Section 10.2.
1. not. negation operator.
2. and. conjunction operator.
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3. or. disjunction operator.
4. xor. exclusive disjunction operator.
ext-operator
Optional. STRING. A means by which to extend the operator
attribute. See Section 5.1.1.
3.29.5. Expressions with IndicatorExpression
Boolean algebraic expressions can be used to specify relationships
between observables and indicators. These expressions are
constructed through the use of the operator attribute and parent-
child relationships in IndicatorExpressions. These expressions
should be parsed as follows:
1. The operator specified by the operator attribute is applied
between each of the child elements of the immediate parent
IndicatorExpression element. If no operator attribute is
specified, it should be assumed to be the conjunction operator
(i.e., operator="and").
2. A nested IndicatorExpression element with a parent
IndicatorExpression is the equivalent of a parentheses in the
expression.
The following examples in Figures 66 through 70 illustrate these
parsing rules:
1 :
2 [O1]: ..
3 [O2]: ..
4 :
Equivalent expression: (O1 AND O2)
Figure 66: Nested Elements in an IndicatorExpression without an
Operator Attribute Specified
1 :
2 [O1]: ..
3 [O2]: ..
4 :
Equivalent expression: (O1 OR O2)
Figure 67: Nested Elements in an IndicatorExpression with an Operator
Attribute Specified
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1 :
2 :
3 [O1]: ..
4 [O2]: ..
5 :
6 [O3]: ..
7 :
Equivalent expression: ((O1 OR O2) OR O3)
Figure 68: Nested Elements with a Recursive IndicatorExpression with
an Operator Attribute Specified
1 :
2 :
3 [O1]: ..
4 [O2]: ..
5 :
6 :
Equivalent expression: (NOT (O1 AND O2))
Figure 69: A Recursive IndicatorExpression with an Operator Attribute
Specified
1 :
2 :
3 [O1 with low confidence] : ..
4 :
5 :
6 :
7 [O2 with high confidence]: ..
8 :
9 :
10 :
Equivalent expression: ((O1) OR (O2))
Figure 70: Varying Confidence on Particular Observables
Invalid algebraic expressions while valid XML MUST NOT be specified.
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3.29.6. ObservableReference Class
The ObservableReference describes a reference to an observable
feature or phenomenon described elsewhere in the document.
The ObservableReference class has no content.
+-------------------------+
| ObservableReference |
+-------------------------+
| IDREF uid-ref |
+-------------------------+
Figure 71: The ObservableReference Class
The ObservableReference class has no content.
The attribute of the ObservableReference class is:
uid-ref
Required. IDREF. An identifier that serves as a reference to a
class in the IODEF document. The referenced class will have this
identifier set in its observable-id attribute.
3.29.7. IndicatorReference Class
The IndicatorReference describes a reference to an indicator. This
reference may be to an indicator described in this IODEF document or
in a previously exchanged IODEF document.
The IndicatorReference class has no content.
+--------------------------+
| IndicatorReference |
+--------------------------+
| IDREF uid-ref |
| STRING euid-ref |
| STRING version |
+--------------------------+
Figure 72: The IndicatorReference Class
The attributes of the IndicatorReference class are:
uid-ref
Optional. IDREF. An identifier that references an Indicator
class in the IODEF document. The referenced Indicator class will
have this identifier set in its IndicatorID class.
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euid-ref
Optional. STRING. An identifier that references an IndicatorID
not in this IODEF document.
version
Optional. STRING. A version number of an indicator.
Either the uid-ref or the euid-ref attribute MUST be set.
3.29.8. AttackPhase Class
The AttackPhase class describes a particular phase of an attack life
cycle.
+------------------------+
| AttackPhase |
+------------------------+
| |<>--{0..*}--[ AttackPhaseID ]
| |<>--{0..*}--[ URL ]
| |<>--{0..*}--[ Description ]
| |<>--{0..*}--[ AdditionalData ]
+------------------------+
Figure 73: The AttackPhase Class
The aggregate classes of the AttackPhase class are:
AttackPhaseID
Zero or more. STRING. An identifier for the phase of the attack.
URL
Zero or more. URL. A URL to a resource describing this phase of
the attack.
Description
Zero or more. ML_STRING. A free-form text description of this
phase of the attack.
AdditionalData
Zero or more. EXTENSION. A mechanism by which to extend the data
model.
AttackPhase MUST have at least one instance of a child class.
The AttackPhase class has no attributes.
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4. Processing Considerations
This section provides additional requirements and guidance on
creating and processing IODEF documents.
4.1. Encoding
Every IODEF document MUST begin with an XML declaration and MUST
specify the XML version used. The character encoding MUST also be
explicitly specified. UTF-8 [RFC3629] SHOULD be used unless UTF-16
[RFC2781] is necessary. Encodings other than UTF-8 and UTF-16 SHOULD
NOT be used. The IODEF conforms to all XML data-encoding conventions
and constraints.
The XML declaration with UTF-8 character encoding will read as
follows:
Certain characters have special meaning in XML and MUST not appear in
literal form. Per Section 2.4 of [W3C.XML], these characters MUST be
escaped with a numeric character or entity reference.
4.2. IODEF Namespace
The IODEF schema declares a namespace of
"urn:ietf:params:xml:ns:iodef-2.0" and registers it per [W3C.XMLNS].
Each IODEF document MUST include a valid reference to the IODEF
schema using the "xsi:schemaLocation" attribute. An example of such
a declaration would look as follows:
4.3. Validation
IODEF documents MUST be well-formed XML. It is RECOMMENDED that
recipients validate the document against the schema described in
Section 8. However, mere conformance to this schema is not
sufficient for a semantically valid IODEF document. The text of
Section 3 describes further formatting and constraints, including
some that cannot be conveniently encoded in the schema. These MUST
also be considered by an IODEF implementation. Furthermore, the
enumerated values present in this document are a static list that
will be incomplete over time as select attributes can be extended by
a corresponding IANA registry per Section 10.2. Therefore, IODEF
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implementations SHOULD periodically update their schema and MAY need
to update their parsing algorithms to incorporate newly registered
values.
4.4. Incompatibilities with v1
The IODEF data model in this document makes a number of changes to
[RFC5070]. These changes were largely additive -- classes and
enumerated values were added. However, some incompatibilities
between [RFC5070] and this new specification were introduced. These
incompatibilities are as follows:
o The IODEF-Document@version attribute is set to "2.0".
o Attributes with enumerated values can now also be extended with
IANA registries.
o All iodef:MLStringType classes use xml:lang. IODEF-Document also
uses xml:lang.
o The Service@ip_protocol attribute was renamed to @ip-protocol.
o The Node/NodeName class was removed in favor of representing
domain names with Node/DomainData/Name class. The Node/DataTime
class was also removed, so that the Node/DomainData/
DateDomainWasChecked class can represent the time at which the
name-to-address resolution occurred.
o The Node/NodeRole class was moved to System/NodeRole.
o The Reference class is now defined by [RFC7495].
o The data previously represented in the Impact class is now in the
SystemImpact and IncidentCategory classes. The Impact class has
been removed.
o The semantics of Counter@type are now represented in Counter@unit.
o The IODEF-Document@formatid attribute has been renamed to @format-
id.
o The Incident/ReportTime class is no longer required. However, the
GenerationTime class is required.
o The Fax class was removed and is now represented by a generic
Telephone class.
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o The Telephone, Email, and PostalAddress classes were redefined
from improved internationalization.
o The "ipv6-net-mask" value was removed from the category attribute
of Address.
5. Extending the IODEF
In order to support the dynamic nature of security operations, the
IODEF data model will need to continue to evolve. This section
discusses how new data elements can be incorporated into the IODEF.
There is support to add additional enumerated values and new classes.
Adding additional attributes to existing classes is not supported.
These extension mechanisms are designed so that adding new data
elements is possible without requiring modifications to this
document. Extensions can be implemented publicly or privately. With
proven value, well-documented extensions can be incorporated into
future versions of the specification.
5.1. Extending the Enumerated Values of Attributes
Additional enumerated values can be added to select attributes either
through the use of specially marked attributes with the "ext-" prefix
or through a set of corresponding IANA registries. The former
approach allows for the extension to remain private. The latter
approach is public.
5.1.1. Private Extension of Enumerated Values
The data model supports adding new enumerated values to an attribute
without public registration. For each attribute that supports this
extension technique, there is a corresponding attribute in the same
element whose name is identical but with a prefix of "ext-". This
special attribute is referred to as the extension attribute. The
attribute being extended is referred to as an extensible attribute.
For example, an extensible attribute named "foo" will have a
corresponding extension attribute named "ext-foo". An element may
have many extensible attributes.
In addition to a corresponding extension attribute, each extensible
attribute has "ext-value" as one its possible enumerated values.
Selection of this particular value in an extensible attribute signals
that the extension attribute contains data. Otherwise, this
"ext-value" value has no meaning.
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In order to add a new enumerated value to an extensible attribute,
the value of this attribute MUST be set to "ext-value", and the new
desired value MUST be set in the corresponding extension attribute.
For example, extending the type attribute of the SystemImpact class
would look as follows:
A given extension attribute MUST NOT be set unless the corresponding
extensible attribute has been set to "ext-value".
5.1.2. Public Extension of Enumerated Values
The data model also supports publicly extending select enumerated
attributes. A new entry can be added by registering a new entry in
the appropriate IANA registry. Section 10.2 provides a mapping
between the extensible attributes and their corresponding registry.
Section 4.3 discusses the XML validation implications of this type of
extension. All extensible attributes that support private extensions
also support public extensions.
5.2. Extending Classes
Classes of the EXTENSION (iodef:ExtensionType) type can extend the
data model. They provide the ability to have new atomic or XML-
encoded data elements in all of the top-level classes of the Incident
class and in a few of the complex subordinate classes. As there are
multiple instances of the extensible classes in the data model, there
is discretion on where to add a new data element. It is RECOMMENDED
that the extension be placed in the most closely related class to the
new information.
Extensions using the atomic data types (i.e., all values of the dtype
attributes other than "xml") MUST:
1. Set the element content to the desired value, and
2. Set the dtype attribute to correspond to the data type of the
element content.
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The following guidelines exist for extensions using XML (i.e.,
dtype="xml"):
1. The element content of the extensible class MUST be set to the
desired value, and the dtype attribute MUST be set to "xml".
2. The extension schema MUST declare a separate namespace. It is
RECOMMENDED that these extensions have the prefix "iodef-". This
recommendation makes readability of the document easier by
allowing the reader to infer which namespaces relate to IODEF by
inspection.
3. It is RECOMMENDED that extension schemas follow the naming
convention of the IODEF data model. This too improves the
readability of extended IODEF documents. The names of all
elements SHOULD be capitalized. For elements with composed
names, a capital letter SHOULD be used for each word. Attribute
names SHOULD be in lowercase. Attributes with composed names
SHOULD be separated by a hyphen.
4. Implementations that encounter an unrecognized element,
attribute, or attribute value in a supported namespace SHOULD
reject the document as a syntax error.
5. There are security and performance implications in requiring
implementations to dynamically download schemas at runtime.
Therefore, implementations MUST NOT download schemas at runtime
unless the appropriate precautions are taken. Implementations
also need to contend with the potential of significant network
and processing issues.
6. Some adopters of the IODEF may have private schema definitions
that are not publicly available. Thus, implementations may
encounter IODEF documents with references to private schemas that
may not be resolvable. Hence, IODEF document recipients MUST be
prepared for a schema definition in an IODEF document never to
resolve.
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The following schema and XML document excerpt provide a template for
an extension schema and its use in the IODEF document.
This example schema defines a namespace of "iodef-extension1" and a
single element named "newdata".
attributeFormDefault="unqualified"
elementFormDefault="qualified">
The following XML excerpt demonstrates the use of the above schema as
an extension to the IODEF.
...
Field that could not be represented elsewhere
5.3. Deconflicting Private Extensions
To disambiguate which private extension is used in an IODEF document,
the data model provides a means to identify the source of an
extension. Two attributes in the IODEF-Document class,
private-enum-name and private-enum-id, are used to specify this
attribution. Only a single private extension can be identified in a
given IODEF-Document.
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If an implementor has a single private extension, then only the
private-enum-name attribute needs to be specified. Multiple distinct
private extensions or versioning of a single extension can be
attributed by also setting the corresponding private-num-id
attribute.
The following XML excerpt demonstrates the specification of a private
extension from "example.com" with an identifier of "13".
...
If an unrecognized private extension is encountered in processing,
the recipient MAY reject the entire document as a syntax error.
6. Internationalization Issues
Internationalization and localization is of specific concern to the
IODEF as it facilitates operational coordination with a diverse set
of partners. The IODEF implements internationalization by relying on
XML constructs and through explicit design choices in the data model.
Since the IODEF is implemented as an XML schema, it supports
different character encodings, such as UTF-8 and UTF-16, that are
possible with XML. Additionally, each IODEF document MUST specify
the language in which its content is encoded. The language can be
specified with the attribute "xml:lang" (per Section 2.12 of
[W3C.XML]) in the top-level element (i.e., IODEF-Document) and lets
all other elements inherit that definition. All IODEF classes with a
free-form text definition (i.e., all those defined with type
iodef:MLStringType) can also specify a language different from the
rest of the document.
The data model supports multiple translations of free-form text. All
ML_STRING (iodef:MLStringType) classes have a one-to-many cardinality
to their parent. This allows the identical text translated into
different languages to be encoded in different instances of the same
class with a common parent. This design also enables the creation of
a single document containing all the translations. The IODEF
implementation SHOULD extract the appropriate language relevant to
the recipient.
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Related instances of a given iodef:MLStringType class that are
translations of each other are identified by a common identifier set
in the translation-id attribute. The example below shows three
instances of a Description class expressed in three different
languages. The relationship between these three instances of the
Description class is conveyed by the common value of "1" in the
translation-id attribute.
...
English
Englisch
Anglais
The IODEF balances internationalization support with the need for
interoperability. While the IODEF supports different languages, the
data model also relies heavily on standardized enumerated attributes
that can crudely approximate the contents of the document. With this
approach, a CSIRT should be able to make some sense of an IODEF
document it receives even if the free-form text data elements are
written in a language unfamiliar to the recipient.
7. Examples
This section provides examples of IODEF documents. These examples do
not represent the full capabilities of the data model or the only way
to encode particular information.
7.1. Minimal Example
A document containing only the mandatory elements and attributes.
492382
2015-07-18T09:00:00-05:00
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contact@csirt.example.com
7.2. Indicators from a Campaign
An example of C2 domains from a given campaign.
897923
TA-12-AGGRESSIVE-BUTTERFLY
Aggressive Butterfly
C-2015-59405
Orange Giraffe
2015-10-02T11:18:00-05:00
Summarizes the Indicators of Compromise
for the Orange Giraffe campaign of the Aggressive
Butterfly crime gang.
CSIRT for example.com
contact@csirt.example.com
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G90823490
C2 domains
2014-12-02T11:18:00-05:00
kj290023j09r34.example.com
09ijk23jfj0k8.example.net
klknjwfjiowjefr923.example.org
oimireik79msd.example.org
8. The IODEF Data Model (XML Schema)
Incident Object Description Exchange Format v2.0
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9. Security Considerations
The IODEF data model does not directly introduce security or privacy
issues. However, as the data encoded by the IODEF might be
considered sensitive by the parties exchanging it or by those
described by it, care needs to be taken to ensure appropriate
handling during the document construction, exchange, processing,
archiving, subsequent retrieval, and analysis.
9.1. Security
The underlying messaging format and protocol used to exchange
instances of the IODEF MUST provide appropriate guarantees of
confidentiality, integrity, and authenticity. The use of a
standardized security protocol is encouraged. The Real-time Inter-
network Defense (RID) protocol [RFC6545] and its associated transport
binding IODEF/RID over HTTP/TLS [RFC6546] provide such security.
An IODEF implementation may act on the data in the document. These
actions might be explicitly requested in the document or the result
of analytical logic that triggered on data in the document. For this
reason, care must be taken by IODEF implementations to properly
authenticate the sender and receiver of the document. The sender
needs confidence that sensitive information and timely requests for
action are sent to the correct recipient. The recipient may
interpret the contents of the document differently based on who sent
it or vary actions based on the sender. While the sender of the
document may explicitly convey confidence in the data in a granular
way using the Confidence class, the recipient is free to ignore or
refine this information to make its own assessment. Ambiguous
Confidence elements (where it is unclear to which of a set of other
elements the Confidence element relates) in a document MUST be
ignored by the recipient.
Certain classes may require out-of-band coordination to agree upon
their semantics (e.g., Confidence@rating="low" or DefinedCOA). This
coordination MUST occur prior to operational data exchange to prevent
the incorrect interpretation of these select data elements. When
parsing these data elements, implementations should validate, when
possible, that they conform to the agreed upon semantics. These
semantics may need to be periodically reevaluated.
Executable content of various forms could be embedded into the IODEF
document directly or through an extension. Implementation MUST
handle this content with care to prevent unintentional automated
execution. The following classes are explicitly intended to
represent content that might be executable:
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o All classes of type iodef:ExtensionType and the RecordPattern
class can represent arbitrary binary strings such as legitimate
software programs or malware.
o The EmailMessage and EmailBody classes can represent email
attachments that can contain arbitrary content.
o The DetectionPattern class could specify a machine-readable
configuration that directs the execution of the corresponding
tool.
Per Section 4.3, IODEF implementations will need to periodically
consult the IANA registries specified in Section 10.2 to discover
newly registered enumerated attribute values. These implementations
MUST communicate with IANA in a way that ensures the integrity of the
values and the authenticity of the source. HTTPS over TLS
[RFC2818][RFC5246] provides such security.
9.2. Privacy
The IODEF contains numerous fields that are identifiers that could be
linked to an individual or organization. IODEF documents may contain
sensitive information about these identified parties; repeated
document exchanges about the same and related parties may enable the
correlation of data about them. Likewise, a party may report on
another to a third party without their knowledge.
When creating an IODEF document, careful consideration must be given
to what information is shared. Personal identifiers and attributable
sensitive information should only be shared when necessary.
When exchanging documents, transport security MUST provide document-
level confidentiality. XML element-level confidentiality can also be
provided by using [W3C.XMLENC].
In order to suggest data processing and handling guidelines of the
encoded information, the IODEF allows a document sender to convey a
privacy policy using the restriction attribute. The various
instances of this attribute allow different data elements of the
document to be covered by dissimilar policies. While flexible, it
must be stressed that this approach only serves as a guideline from
the sender, as the recipient is free to ignore it.
Although outside of the scope of an IODEF implementation, the
contents of IODEF documents and any derived analysis should be
archived with appropriate confidentiality controls. Likewise, access
to retrieve and analyze this data should be restricted to authorized
users.
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10. IANA Considerations
This document registers a namespace, an XML schema, and a number of
registries that map to enumerated values defined in the data model.
It also defines an Expert Review process for IODEF-related XML
registry entries.
10.1. Namespace and Schema
This document uses URNs to describe an XML namespace and schema
conforming to a registry mechanism described in [RFC3688].
Registration for the IODEF namespace:
o URI: urn:ietf:params:xml:ns:iodef-2.0
o Registrant Contact: See the author in the "Author's Address"
section of this document.
o XML: None. Namespace URIs do not represent an XML specification.
Registration for the IODEF XML schema:
o URI: urn:ietf:params:xml:schema:iodef-2.0
o Registrant Contact: See the first author of the "Author's Address"
section of this document.
o XML: See Section 8 of this document.
10.2. Enumerated Value Registries
This document creates 34 identically structured registries to be
managed by IANA:
o Name of the parent registry: "Incident Object Description Exchange
Format v2 (IODEF)"
o URL of the registry:
o Namespace format: A registry entry consists of:
* Value. A value for a given IODEF attribute. It MUST conform
to the formatting specified by the IODEF ENUM data type which
is implemented as an "xs:NMTOKEN" type per Section 3.3.4 of
[W3C.SCHEMA.DTYPES]. The value SHOULD conform to the
convention specified in Section 5.2.
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* Description. A short description of the enumerated value.
* Reference. An optional list of URIs to further describe the
value.
o Allocation policy: Expert Review per [RFC5226]. This reviewer
will ensure that the requested registry entry conforms to the
prescribed formatting. The reviewer will also ensure that the
entry is an appropriate value for the attribute per the
information model (Section 3).
The registries to be created are named in the "Registry Name" column
of Table 1. Each registry is initially populated with values and
descriptions that come from an attribute specified in the IODEF
schema (Section 8) whose description is found in a sub-section of the
information model (Section 3). The initial values for the Value and
Description fields of a given registry are listed in the "IV (Value)"
and "IV (Desc.)" columns, respectively. The "IV (Value)" points to a
given schema type per Section 8. Each enumerated value in the schema
gets a corresponding entry in a given registry. The "IV (Desc.)"
points to a section in the text of this document that describes each
enumerated value. The initial value of the Reference field of every
registry entry described below should be this document.
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+-------------------------+-----------------------------+-----------+
| Registry Name | IV (Value) | IV |
| | | (Desc.) |
+-------------------------+-----------------------------+-----------+
| Restriction | iodef-restriction-type | 3.3.1 |
| | | |
| Incident-purpose | incident-purpose-type | 3.2 |
| | | |
| Incident-status | incident-status-type | 3.2 |
| | | |
| Contact-role | contact-role-type | 3.9 |
| | | |
| Contact-type | contact-type-type | 3.9 |
| | | |
| RegistryHandle-registry | registryhandle-registry- | 3.9.1 |
| | type | |
| | | |
| PostalAddress-type | postaladdress-type-type | 3.9.2 |
| | | |
| Telephone-type | telephone-type-type | 3.9.4 |
| | | |
| Email-type | email-type-type | 3.9.3 |
| | | |
| Expectation-action | action-type | 3.15 |
| | | |
| Discovery-source | discovery-source-type | 3.10 |
| | | |
| SystemImpact-type | systemimpact-type-type | 3.12.1 |
| | | |
| BusinessImpact-severity | businessimpact-severity- | 3.12.2 |
| | type | |
| | | |
| BusinessImpact-type | businessimpact-type-type | 3.12.2 |
| | | |
| TimeImpact-metric | timeimpact-metric-type | 3.12.3 |
| | | |
| TimeImpact-duration | duration-type | 3.12.3 |
| | | |
| Confidence-rating | confidence-rating-type | 3.12.5 |
| | | |
| NodeRole-category | noderole-category-type | 3.18.2 |
| | | |
| System-category | system-category-type | 3.17 |
| | | |
| System-ownership | system-ownership-type | 3.17 |
| | | |
| Address-category | address-category-type | 3.18.1 |
| | | |
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| Counter-type | counter-type-type | 3.18.3 |
| | | |
| Counter-unit | counter-unit-type | 3.18.3 |
| | | |
| DomainData-system- | domaindata-system-status- | 3.19 |
| status | type | |
| | | |
| DomainData-domain- | domaindata-domain-status- | 3.19 |
| status | type | |
| | | |
| RecordPattern-type | recordpattern-type-type | 3.22.2 |
| | | |
| RecordPattern- | recordpattern-offsetunit- | 3.22.2 |
| offsetunit | type | |
| | | |
| Key-registryaction | key-registryaction-type | 3.23.1 |
| | | |
| HashData-scope | hashdata-scope-type | 3.26 |
| | | |
| BulkObservable-type | bulkobservable-type-type | 3.29.3.1 |
| | | |
| IndicatorExpression- | indicatorexpression- | 3.29.4 |
| operator | operator-type | |
| | | |
| ExtensionType-dtype | dtype-type | 2.16 |
| | | |
| SoftwareReference-spec- | softwarereference-spec-id- | 2.15.1 |
| id | type | |
| | | |
| SoftwareReference-dtype | softwarereference-dtype- | 2.15.1 |
| | type | |
+-------------------------+-----------------------------+-----------+
Table 1: IANA Enumerated Value Registries
10.3. Expert Review of IODEF-Related XML Registry Entries
IODEF class extensions, per Section 5.2, could register their
namespaces and schemas with the IANA XML namespace ("ns" on
) and schema
registries ("schema" on ) described in [RFC3688]. In addition to any reviews
required by IANA, changes to the XML "schema" registry for schema
names beginning with "urn:ietf:params:xml:schema:iodef" are subject
to an additional IODEF Expert Review [RFC5226] to ensure
compatibility with IODEF and other existing IODEF extensions.
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The IODEF expert(s) for these reviews will be designated by the IETF
Security Area Directors.
This document obsoletes [RFC6685].
11. References
11.1. Normative References
[E.164] ITU Telecommunication Standardization Sector, "The
International Public Telecommunication Numbering Plan",
ITU-T Recommendation E.164, November 2010.
[IANA.Media]
IANA, "Media Types",
.
[IANA.Ports]
IANA, "Service Name and Transport Protocol Port Number
Registry", .
[IANA.Protocols]
IANA, "Assigned Internet Protocol Numbers",
.
[IEEE.POSIX]
IEEE, "Information Technology - Portable Operating System
Interface (POSIX) Base Specifications, Issue 7", IEEE
Std 1003.1-2001, DOI 10.1109/IEEESTD.2009.5393893,
September 2009.
[ISO19770] International Organization for Standardization,
"Information technology -- Software asset management --
Part 2: Software identification tag", ISO
Standard 19770-2:2015, October 2015.
[ISO4217] International Organization for Standardization, "Codes for
the representation of currencies", ISO 4217:2015, 2015.
[NIST.CPE] Cheikes, B., Waltermire, D., and K. Scarfone, "Common
Platform Enumeration: Naming Specification Version 2.3",
NIST Interagency Report 7695, August 2011,
.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
.
[RFC2781] Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO
10646", RFC 2781, DOI 10.17487/RFC2781, February 2000,
.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, .
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, .
[RFC4519] Sciberras, A., Ed., "Lightweight Directory Access Protocol
(LDAP): Schema for User Applications", RFC 4519,
DOI 10.17487/RFC4519, June 2006,
.
[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
DOI 10.17487/RFC5322, October 2008,
.
[RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
September 2009, .
[RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
Address Text Representation", RFC 5952,
DOI 10.17487/RFC5952, August 2010,
.
[RFC6531] Yao, J. and W. Mao, "SMTP Extension for Internationalized
Email", RFC 6531, DOI 10.17487/RFC6531, February 2012,
.
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RFC 7970 IODEF Version 2 November 2016
[RFC7203] Takahashi, T., Landfield, K., and Y. Kadobayashi, "An
Incident Object Description Exchange Format (IODEF)
Extension for Structured Cybersecurity Information",
RFC 7203, DOI 10.17487/RFC7203, April 2014,
.
[RFC7495] Montville, A. and D. Black, "Enumeration Reference Format
for the Incident Object Description Exchange Format
(IODEF)", RFC 7495, DOI 10.17487/RFC7495, March 2015,
.
[W3C.SCHEMA]
Thompson, H., Beech, D., Maloney, M., and N. Mendelsohn,
"XML Schema Part 1: Structures Second Edition", W3C
Recommendation REC-xmlschema-1-20041028, October 2004,
.
[W3C.SCHEMA.DTYPES]
Biron, P. and A. Malhotra, "XML Schema Part 2: Datatypes
Second Edition", W3C Recommendation REC-xmlschema-
2-20041028, October 2004,
.
[W3C.XML] Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and
F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth
Edition)", W3C Recommendation REC-xml-20081126, November
2008, .
[W3C.XMLNS]
Bray, T., Hollander, D., Layman, A., Tobin, R., and H.
Thompson, "Namespaces in XML 1.0 (Third Edition)", W3C
Recommendation REC-xml-names-20091208, December 2009,
.
[W3C.XMLSIG]
Eastlake, D., Reagle, J., Solo, D., Hirsch, F., and T.
Roessler, "XML Signature Syntax and Processing (Second
Edition)", W3C Recommendation REC-xmldsig-core-20080610,
June 2008, .
[W3C.XPATH]
Robie, J., Dyck, M., and J. Spiegel, "XML Path Language
(XPath) 3.1", W3C Candidate Recommendation CR-xpath-
31-20151217, December 2015,
.
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11.2. Informative References
[KB310516] Microsoft Corporation, "How to add, modify, or delete
registry subkeys and values by using a .reg file",
September 2013,
.
[NIST800.61rev2]
National Institute of Standards and Technology, "Computer
Security Incident Handling Guide", NIST Special
Publication 800-61, Revision 2, August 2012,
.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000,
.
[RFC3982] Newton, A. and M. Sanz, "IRIS: A Domain Registry (dreg)
Type for the Internet Registry Information Service
(IRIS)", RFC 3982, DOI 10.17487/RFC3982, January 2005,
.
[RFC4180] Shafranovich, Y., "Common Format and MIME Type for Comma-
Separated Values (CSV) Files", RFC 4180,
DOI 10.17487/RFC4180, October 2005,
.
[RFC5070] Danyliw, R., Meijer, J., and Y. Demchenko, "The Incident
Object Description Exchange Format", RFC 5070,
DOI 10.17487/RFC5070, December 2007,
.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
.
[RFC5901] Cain, P. and D. Jevans, "Extensions to the IODEF-Document
Class for Reporting Phishing", RFC 5901,
DOI 10.17487/RFC5901, July 2010,
.
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[RFC6545] Moriarty, K., "Real-time Inter-network Defense (RID)",
RFC 6545, DOI 10.17487/RFC6545, April 2012,
.
[RFC6546] Trammell, B., "Transport of Real-time Inter-network
Defense (RID) Messages over HTTP/TLS", RFC 6546,
DOI 10.17487/RFC6546, April 2012,
.
[RFC6685] Trammell, B., "Expert Review for Incident Object
Description Exchange Format (IODEF) Extensions in IANA XML
Registry", RFC 6685, DOI 10.17487/RFC6685, July 2012,
.
[W3C.XMLENC]
Eastlake, D., Reagle, J., Solo, D., Hirsch, F., Nystrom,
M., Roessler, T., and K. Yiu, "XML Encryption Syntax and
Processing Version 1.1", W3C Recommendation REC-xmldsig-
core1-20130411, April 2013,
.
Acknowledgments
Thanks to Paul Stoecker for his editorial leadership in the
transition of an early draft to the current document.
Thanks to Kathleen Moriarty, Brian Trammel, Alexey Melnikov, Takeshi
Takahashi, David Waltermire, and Sean Turner (as the MILE working
group chairs, secretary, and area directors) for providing feedback
and coordination of this document.
Thanks to the following individuals (listed alphabetically) who
provided feedback during the meetings, on the mailing list, or
through implementation experience: Jerome Athias, David Black, Eric
Burger, Toma Cejka, Patrick Curry, John Field, Christopher
Harrington, Chris Inacio, Panos Kampanakis, David Misell, Daisuke
Miyamoto, Adam Montville, Robert Moskowitz, Lagadec Philippe, Tony
Rutkowski, Mio Suzuki, and Nik Teague.
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Author's Address
Roman Danyliw
CERT
Software Engineering Institute
Carnegie Mellon University
4500 Fifth Avenue
Pittsburgh, PA
United States of America
Email: rdd@cert.org
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