Статус этой заметки
В этом документе указан протокол отслеживания стандартов Интернета для
Интернет-сообщества, а также просит обсудить и
улучшения. Пожалуйста, обратитесь к текущему изданию «Интернет
Официальные стандарты протокола "(STD 1) для состояния стандартизации
и статус этого протокола. Распространение этой заметки неограниченно.
Абстрактные
Формат обмена данными об объекте инцидента (IODEF) определяет
представление данных, которое обеспечивает основу для обмена информацией
обычно обмениваются командами реагирования на инциденты с компьютерной безопасностью
(CSIRT) об инцидентах компьютерной безопасности. В этом документе описывается
информационной модели для IODEF и предоставляет связанные данные
модель, указанная в XML-схеме.
=====================================
Network Working Group R. Danyliw
Request for Comments: 5070 CERT
Category: Standards Track J. Meijer
UNINETT
Y. Demchenko
University of Amsterdam
December 2007
The Incident Object Description Exchange Format
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Abstract
The Incident Object Description Exchange Format (IODEF) defines a
data representation that provides a framework for sharing information
commonly exchanged by Computer Security Incident Response Teams
(CSIRTs) about computer security incidents. This document describes
the information model for the IODEF and provides an associated data
model specified with XML Schema.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.2. Notations . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. About the IODEF Data Model . . . . . . . . . . . . . . . . 5
1.4. About the IODEF Implementation . . . . . . . . . . . . . . 6
2. IODEF Data Types . . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Integers . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2. Real Numbers . . . . . . . . . . . . . . . . . . . . . . . 7
2.3. Characters and Strings . . . . . . . . . . . . . . . . . . 7
2.4. Multilingual Strings . . . . . . . . . . . . . . . . . . . 7
2.5. Bytes . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.6. Hexadecimal Bytes . . . . . . . . . . . . . . . . . . . . 7
2.7. Enumerated Types . . . . . . . . . . . . . . . . . . . . . 8
2.8. Date-Time Strings . . . . . . . . . . . . . . . . . . . . 8
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2.9. Timezone String . . . . . . . . . . . . . . . . . . . . . 8
2.10. Port Lists . . . . . . . . . . . . . . . . . . . . . . . . 8
2.11. Postal Address . . . . . . . . . . . . . . . . . . . . . . 9
2.12. Person or Organization . . . . . . . . . . . . . . . . . . 9
2.13. Telephone and Fax Numbers . . . . . . . . . . . . . . . . 9
2.14. Email String . . . . . . . . . . . . . . . . . . . . . . . 9
2.15. Uniform Resource Locator strings . . . . . . . . . . . . . 9
3. The IODEF Data Model . . . . . . . . . . . . . . . . . . . . . 9
3.1. IODEF-Document Class . . . . . . . . . . . . . . . . . . . 10
3.2. Incident Class . . . . . . . . . . . . . . . . . . . . . . 10
3.3. IncidentID Class . . . . . . . . . . . . . . . . . . . . . 14
3.4. AlternativeID Class . . . . . . . . . . . . . . . . . . . 14
3.5. RelatedActivity Class . . . . . . . . . . . . . . . . . . 15
3.6. AdditionalData Class . . . . . . . . . . . . . . . . . . . 16
3.7. Contact Class . . . . . . . . . . . . . . . . . . . . . . 18
3.7.1. RegistryHandle Class . . . . . . . . . . . . . . . . . 21
3.7.2. PostalAddress Class . . . . . . . . . . . . . . . . . 22
3.7.3. Email Class . . . . . . . . . . . . . . . . . . . . . 22
3.7.4. Telephone and Fax Classes . . . . . . . . . . . . . . 23
3.8. Time Classes . . . . . . . . . . . . . . . . . . . . . . . 23
3.8.1. StartTime . . . . . . . . . . . . . . . . . . . . . . 24
3.8.2. EndTime . . . . . . . . . . . . . . . . . . . . . . . 24
3.8.3. DetectTime . . . . . . . . . . . . . . . . . . . . . . 24
3.8.4. ReportTime . . . . . . . . . . . . . . . . . . . . . . 24
3.8.5. DateTime . . . . . . . . . . . . . . . . . . . . . . . 24
3.9. Method Class . . . . . . . . . . . . . . . . . . . . . . . 24
3.9.1. Reference Class . . . . . . . . . . . . . . . . . . . 25
3.10. Assessment Class . . . . . . . . . . . . . . . . . . . . . 25
3.10.1. Impact Class . . . . . . . . . . . . . . . . . . . . . 27
3.10.2. TimeImpact Class . . . . . . . . . . . . . . . . . . . 29
3.10.3. MonetaryImpact Class . . . . . . . . . . . . . . . . . 30
3.10.4. Confidence Class . . . . . . . . . . . . . . . . . . . 31
3.11. History Class . . . . . . . . . . . . . . . . . . . . . . 32
3.11.1. HistoryItem Class . . . . . . . . . . . . . . . . . . 33
3.12. EventData Class . . . . . . . . . . . . . . . . . . . . . 34
3.12.1. Relating the Incident and EventData Classes . . . . . 36
3.12.2. Cardinality of EventData . . . . . . . . . . . . . . . 37
3.13. Expectation Class . . . . . . . . . . . . . . . . . . . . 37
3.14. Flow Class . . . . . . . . . . . . . . . . . . . . . . . . 40
3.15. System Class . . . . . . . . . . . . . . . . . . . . . . . 40
3.16. Node Class . . . . . . . . . . . . . . . . . . . . . . . . 42
3.16.1. Counter Class . . . . . . . . . . . . . . . . . . . . 43
3.16.2. Address Class . . . . . . . . . . . . . . . . . . . . 45
3.16.3. NodeRole Class . . . . . . . . . . . . . . . . . . . . 46
3.17. Service Class . . . . . . . . . . . . . . . . . . . . . . 48
3.17.1. Application Class . . . . . . . . . . . . . . . . . . 50
3.18. OperatingSystem Class . . . . . . . . . . . . . . . . . . 51
3.19. Record Class . . . . . . . . . . . . . . . . . . . . . . . 51
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3.19.1. RecordData Class . . . . . . . . . . . . . . . . . . . 51
3.19.2. RecordPattern Class . . . . . . . . . . . . . . . . . 53
3.19.3. RecordItem Class . . . . . . . . . . . . . . . . . . . 54
4. Processing Considerations . . . . . . . . . . . . . . . . . . 54
4.1. Encoding . . . . . . . . . . . . . . . . . . . . . . . . . 54
4.2. IODEF Namespace . . . . . . . . . . . . . . . . . . . . . 55
4.3. Validation . . . . . . . . . . . . . . . . . . . . . . . . 55
5. Extending the IODEF . . . . . . . . . . . . . . . . . . . . . 56
5.1. Extending the Enumerated Values of Attributes . . . . . . 56
5.2. Extending Classes . . . . . . . . . . . . . . . . . . . . 57
6. Internationalization Issues . . . . . . . . . . . . . . . . . 59
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
7.1. Worm . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
7.2. Reconnaissance . . . . . . . . . . . . . . . . . . . . . . 61
7.3. Bot-Net Reporting . . . . . . . . . . . . . . . . . . . . 63
7.4. Watch List . . . . . . . . . . . . . . . . . . . . . . . . 65
8. The IODEF Schema . . . . . . . . . . . . . . . . . . . . . . . 66
9. Security Considerations . . . . . . . . . . . . . . . . . . . 87
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 88
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 88
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 89
12.1. Normative References . . . . . . . . . . . . . . . . . . . 89
12.2. Informative References . . . . . . . . . . . . . . . . . . 90
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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 bot-
network, or sharing watch-lists of known malicious IP addresses 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). It
provides an XML representation for conveying incident information
across administrative domains between parties that have an
operational responsibility of remediation or a watch-and-warning over
a defined constituency. The data model encodes information about
hosts, networks, and the services running on these systems; attack
methodology and associated forensic evidence; impact of the activity;
and limited approaches for documenting workflow.
The overriding purpose of the IODEF is to enhance the operational
capabilities of CSIRTs. Community adoption of the IODEF provides an
improved ability to resolve incidents and convey situational
awareness by simplifying collaboration and data sharing. This
structured format provided by the IODEF allows for:
o increased automation in processing of incident data, since the
resources of security analysts to parse free-form textual
documents will be reduced;
o decreased effort in normalizing similar data (even when highly
structured) from different sources; and
o a common format on which to build interoperable tools for incident
handling and subsequent analysis, specifically when data comes
from multiple constituencies.
Coordinating with other CSIRTs is not strictly a technical problem.
There are numerous procedural, trust, and legal considerations that
might prevent an organization from sharing information. The IODEF
does not attempt to address them. However, operational
implementations of the IODEF will need to consider this broader
context.
Sections 3 and 8 specify the IODEF data model with text and an XML
schema. The types used by the data model are covered in Section 2.
Processing considerations, the handling of extensions, and
internationalization issues related to the data model are covered in
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Sections 4, 5, and 6, respectively. Examples are listed in Section
7. Section 1 provides the background for the IODEF, and Section 9
documents the security considerations.
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 [6].
Definitions for some of the common computer security-related
terminology used in this document can be found in Section 2 of [16].
1.2. Notations
The normative IODEF data model is specified with the text in Section
3 and the XML schema in Section 8. To help 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.
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 specific elements and
attributes of the IODEF schema. The terms "class" and "element" will
be used interchangeably to reference either the corresponding data
element in the information or data models, respectively.
1.3. About the IODEF Data Model
The IODEF data model is a data representation that provides a
framework for sharing information commonly exchanged by CSIRTs about
computer security incidents. A number of considerations were made in
the design of the data model.
o The data model serves as a transport format. Therefore, its
specific representation is not the optimal representation for on-
disk storage, long-term archiving, or in-memory processing.
o As there is no precise widely agreed upon definition for an
incident, the data model does not attempt to dictate one through
its implementation. Rather, a broad understanding is assumed in
the IODEF that is flexible enough to encompass most operators.
o Describing an incident for all definitions would require an
extremely complex data model. Therefore, the IODEF only intends
to be a framework to convey commonly exchanged incident
information. It ensures that there are ample mechanisms for
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extensibility to support organization-specific information, and
techniques to reference information kept outside of the explicit
data model.
o The domain of security analysis is not fully standardized and must
rely on free-form textual descriptions. The IODEF attempts to
strike a balance between supporting this free-form content, while
still allowing automated processing of incident information.
o The IODEF is only one of several security relevant data
representations being standardized. Attempts were made to ensure
they were complimentary. The data model of the Intrusion
Detection Message Exchange Format [17] influenced the design of
the IODEF.
Further discussion of the desirable properties for the IODEF can be
found in the Requirements for the Format for Incident Information
Exchange (FINE) [16].
1.4. About the IODEF Implementation
The IODEF implementation is specified as an Extensible Markup
Language (XML) [1] Schema [2] in Section 8.
Implementing the IODEF in XML provides numerous advantages. Its
extensibility makes it ideal for specifying a data encoding framework
that supports various character encodings. Likewise, the abundance
of related technologies (e.g., XSL, XPath, XML-Signature) makes for
simplified manipulation. However, XML is fundamentally a text
representation, which makes it inherently inefficient when binary
data must be embedded or large volumes of data must be exchanged.
2. IODEF Data Types
The various data elements of the IODEF data model are typed. This
section discusses these data types. When possible, native Schema
data types were adopted, but for more complicated formats, regular
expressions (see Appendix F of [3]) or external standards were used.
2.1. Integers
An integer is represented by the INTEGER data type. Integer data
MUST be encoded in Base 10.
The INTEGER data type is implemented as an "xs:integer" [3] in the
schema.
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2.2. Real Numbers
Real (floating-point) attributes are represented by the REAL data
type. Real data MUST be encoded in Base 10.
The REAL data type is implemented as an "xs:float" [3] in the schema.
2.3. Characters and Strings
A single character is represented by the CHARACTER data type. A
character 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 implement as an "xs:string"
[3] in the schema.
2.4. Multilingual Strings
STRING data that represents multi-character attributes in a language
different than the default encoding of the document is of the
ML_STRING data type.
The ML_STRING data type is implemented as an "iodef:MLStringType" in
the schema.
2.5. Bytes
A binary octet is represented by the BYTE data type. A sequence of
binary octets is represented by the BYTE[] data type. These octets
are encoded using base64.
The BYTE data type is implemented as an "xs:base64Binary" [3] in the
schema.
2.6. Hexadecimal Bytes
A binary octet is represented by the HEXBIN (and HEXBIN[]) data type.
This octet is encoded as a character tuple consisting of two
hexadecimal digits.
The HEXBIN data type is implemented as an "xs:hexBinary" [3] in the
schema.
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2.7. Enumerated Types
Enumerated types are represented by the ENUM data type, and consist
of an ordered list of acceptable values. Each value has a
representative keyword. Within the IODEF schema, the enumerated type
keywords are used as attribute values.
The ENUM data type is implemented as a series of "xs:NMTOKEN" in the
schema.
2.8. Date-Time Strings
Date-time strings are represented by the DATETIME data type. Each
date-time string identifies a particular instant in time; ranges are
not supported.
Date-time strings are formatted according to a subset of ISO 8601:
2000 [13] documented in RFC 3339 [12].
The DATETIME data type is implemented as an "xs:dateTime" [3] in the
schema.
2.9. Timezone String
A timezone offset from UTC is represented 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 as an "xs:string" with a
regular expression constraint in the schema. This regular expression
is identical to the timezone representation implemented in an "xs:
dateTime".
2.10. Port Lists
A list of network ports are represented 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".
The PORTLIST data type is implemented as an "xs:string" with a
regular expression constraint in the schema.
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2.11. Postal Address
A postal address is represented by the POSTAL data type. This data
type is an ML_STRING whose format is documented in Section 2.23 of
RFC 4519 [10]. It defines a postal address as a free-form multi-line
string separated by the "$" character.
The POSTAL data type is implemented as an "xs:string" in the schema.
2.12. Person or Organization
The name of an individual or organization is represented by the NAME
data type. This data type is an ML_STRING whose format is documented
in Section 2.3 of RFC 4519 [10].
The NAME data type is implemented as an "xs:string" in the schema.
2.13. Telephone and Fax Numbers
A telephone or fax number is represented by the PHONE data type. The
format of the PHONE data type is documented in Section 2.35 of RFC
4519 [10].
The PHONE data type is implemented as an "xs:string" in the schema.
2.14. Email String
An email address is represented by the EMAIL data type. The format
of the EMAIL data type is documented in Section 3.4.1 RFC 2822 [11]
The EMAIL data type is implemented as an "xs:string" in the schema.
2.15. Uniform Resource Locator strings
A uniform resource locator (URL) is represented by the URL data type.
The format of the URL data type is documented in RFC 2396 [8].
The URL data type is implemented as an "xs:anyURI" in the schema.
3. The IODEF Data Model
In this section, the individual components of the IODEF data model
will be discussed in detail. For each class, the semantics will be
described and the relationship with other classes will be depicted
with UML. When necessary, specific comments will be made about
corresponding definition in the schema in Section 8
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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 lang |
| STRING formatid |
+-----------------+
Figure 1: IODEF-Document Class
The aggregate class that constitute IODEF-Document is:
Incident
One or more. The information related to a single incident.
The IODEF-Document class has three attributes:
version
Required. STRING. The IODEF specification version number to
which this IODEF document conforms. The value of this attribute
MUST be "1.00"
lang
Required. ENUM. A valid language code per RFC 4646 [7]
constrained by the definition of "xs:language". The
interpretation of this code is described in Section 6.
formatid
Optional. STRING. A free-form string to convey processing
instructions to the recipient of the document. Its semantics must
be negotiated out-of-band.
3.2. Incident Class
Every incident is represented by an instance of the Incident class.
This class provides a standardized representation for commonly
exchanged incident data.
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+--------------------+
| Incident |
+--------------------+
| ENUM purpose |<>----------[ IncidentID ]
| STRING ext-purpose |<>--{0..1}--[ AlternativeID ]
| ENUM lang |<>--{0..1}--[ RelatedActivity ]
| ENUM restriction |<>--{0..1}--[ DetectTime ]
| |<>--{0..1}--[ StartTime ]
| |<>--{0..1}--[ EndTime ]
| |<>----------[ ReportTime ]
| |<>--{0..*}--[ Description ]
| |<>--{1..*}--[ Assessment ]
| |<>--{0..*}--[ Method ]
| |<>--{1..*}--[ Contact ]
| |<>--{0..*}--[ EventData ]
| |<>--{0..1}--[ History ]
| |<>--{0..*}--[ AdditionalData ]
+--------------------+
Figure 2: The Incident Class
The aggregate classes that constitute Incident are:
IncidentID
One. An incident tracking number assigned to this incident by the
CSIRT that generated the IODEF document.
AlternativeID
Zero or one. The incident tracking numbers used by other CSIRTs
to refer to the incident described in the document.
RelatedActivity
Zero or one. The incident tracking numbers of related incidents.
DetectTime
Zero or one. The time the incident was first detected.
StartTime
Zero or one. The time the incident started.
EndTime
Zero or one. The time the incident ended.
ReportTime
One. The time the incident was reported.
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Description
Zero or more. ML_STRING. A free-form textual description of the
incident.
Assessment
One or more. A characterization of the impact of the incident.
Method
Zero or more. The techniques used by the intruder in the
incident.
Contact
One or more. Contact information for the parties involved in the
incident.
EventData
Zero or more. Description of the events comprising the incident.
History
Zero or one. A log of significant events or actions that occurred
during the course of handling the incident.
AdditionalData
Zero or more. Mechanism by which to extend the data model.
The Incident class has four attributes:
purpose
Required. ENUM. The purpose attribute represents the reason why
the IODEF document was created. It is closely related to the
Expectation class (Section 3.13). This attribute is defined as an
enumerated list:
1. traceback. The document was sent for trace-back purposes.
2. mitigation. The document was sent to request aid in
mitigating the described activity.
3. reporting. The document was sent to comply with reporting
requirements.
4. other. The document was sent for purposes specified in the
Expectation class.
5. ext-value. An escape value used to extend this attribute.
See Section 5.1.
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RFC 5070 IODEF December 2007
ext-purpose
Optional. STRING. A means by which to extend the purpose
attribute. See Section 5.1.
lang
Optional. ENUM. A valid language code per RFC 4646 [7]
constrained by the definition of "xs:language". The
interpretation of this code is described in Section 6.
restriction
Optional. ENUM. This 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 specified
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.
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.
1. public. There are no restrictions placed in the information.
2. need-to-know. The information may be shared with other
parties that are involved in the incident as determined by the
recipient of this document (e.g., multiple victim sites can be
informed of each other).
3. private. The information may not be shared.
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4. default. The information can be shared according to an
information disclosure policy pre-arranged by the
communicating parties.
3.3. IncidentID Class
The IncidentID class represents an incident tracking number that is
unique in the context of the CSIRT and identifies the activity
characterized in an IODEF Document. This identifier would serve as
an index into the CSIRT incident handling 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 |
+------------------+
Figure 3: The IncidentID Class
The IncidentID class has three attributes:
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.
instance
Optional. STRING. An identifier referencing a subset of the
named incident.
restriction
Optional. ENUM. This attribute has been defined in Section 3.2.
3.4. AlternativeID Class
The AlternativeID class lists the incident tracking numbers used by
CSIRTs, other than the one generating the document, to refer to the
identical activity described the IODEF document. A tracking number
listed as an AlternativeID references the same incident detected by
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another CSIRT. The incident tracking numbers of the CSIRT that
generated the IODEF document should never be considered an
AlternativeID.
+------------------+
| AlternativeID |
+------------------+
| ENUM restriction |<>--{1..*}--[ IncidentID ]
| |
+------------------+
Figure 4: The AlternativeID Class
The aggregate class that constitutes AlternativeID is:
IncidentID
One or more. The incident tracking number of another CSIRT.
The AlternativeID class has one attribute:
restriction
Optional. ENUM. This attribute has been defined in Section 3.2.
3.5. RelatedActivity Class
The RelatedActivity class lists either incident tracking numbers of
incidents or URLs (not both) that refer to activity related to the
one described in the IODEF document. These references may be to
local incident tracking numbers or to those of other CSIRTs.
The specifics of how a CSIRT comes to believe that two incidents are
related are considered out of scope.
+------------------+
| RelatedActivity |
+------------------+
| ENUM restriction |<>--{0..*}--[ IncidentID ]
| |<>--{0..*}--[ URL ]
+------------------+
Figure 5: RelatedActivity Class
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The aggregate classes that constitutes RelatedActivity are:
IncidentID
One or more. The incident tracking number of a related incident.
URL
One or more. URL. A URL to activity related to this incident.
The RelatedActivity class has one attribute:
restriction
Optional. ENUM. This attribute has been defined in Section 3.2.
3.6. AdditionalData Class
The AdditionalData class serves as an extension mechanism for
information not otherwise represented in the data model. For
relatively simple information, atomic data types (e.g., integers,
strings) are provided with a mechanism to annotate their meaning.
The class can also be used to extend the data model (and the
associated Schema) to support proprietary extensions by encapsulating
entire XML documents conforming to another Schema (e.g., IDMEF). A
detailed discussion for extending the data model and the schema can
be found in Section 5.
Unlike XML, which is self-describing, atomic data must be documented
to convey its meaning. This information is described in the
'meaning' attribute. Since these description are outside the scope
of the specification, some additional coordination may be required to
ensure that a recipient of a document using the AdditionalData
classes can make sense of the custom extensions.
+------------------+
| AdditionalData |
+------------------+
| ANY |
| |
| ENUM dtype |
| STRING ext-dtype |
| STRING meaning |
| STRING formatid |
| ENUM restriction |
+------------------+
Figure 6: The AdditionalData Class
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The AdditionalData class has five attributes:
dtype
Required. ENUM. The data type of the element content. The
permitted values for this attribute are shown below. The default
value is "string".
1. boolean. The element content is of type BOOLEAN.
2. byte. The element content is of type BYTE.
3. character. The element content is of type CHARACTER.
4. date-time. The element content is of type DATETIME.
5. integer. The element content is of type INTEGER.
6. portlist. The element content is of type PORTLIST.
7. real. The element content is of type REAL.
8. string. The element content is of type STRING.
9. file. The element content is a base64 encoded binary file
encoded as a BYTE[] type.
10. frame. The element content is a layer-2 frame encoded as a
HEXBIN type.
11. packet. The element content is a layer-3 packet encoded as a
HEXBIN type.
12. ipv4-packet. The element content is an IPv4 packet encoded
as a HEXBIN type.
13. ipv6-packet. The element content is an IPv6 packet encoded
as a HEXBIN type.
14. path. The element content is a file-system path encoded as a
STRING type.
15. url. The element content is of type URL.
16. csv. The element content is a common separated value (CSV)
list per Section 2 of [20] encoded as a STRING type.
17. winreg. The element content is a Windows registry key
encoded as a STRING type.
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18. xml. The element content is XML (see Section 5).
19. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-dtype
Optional. STRING. A means by which to extend the dtype
attribute. See Section 5.1.
meaning
Optional. STRING. A free-form description of the element
content.
formatid
Optional. STRING. An identifier referencing the format and
semantics of the element content.
restriction
Optional. ENUM. This attribute has been defined in Section 3.2.
3.7. 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 inheriting definition of Contact provides a way to relate
information without requiring the explicit use of identifiers in the
classes 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. As such, multiple points of contact might be
specified in a single instance of a Contact class. Each child
Contact class logically inherits contact information from its
ancestors.
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+------------------+
| Contact |
+------------------+
| ENUM role |<>--{0..1}--[ ContactName ]
| STRING ext-role |<>--{0..*}--[ Description ]
| ENUM type |<>--{0..*}--[ RegistryHandle ]
| STRING ext-type |<>--{0..1}--[ PostalAddress ]
| ENUM restriction |<>--{0..*}--[ Email ]
| |<>--{0..*}--[ Telephone ]
| |<>--{0..1}--[ Fax ]
| |<>--{0..1}--[ Timezone ]
| |<>--{0..*}--[ Contact ]
| |<>--{0..*}--[ AdditionalData ]
+------------------+
Figure 7: The Contact Class
The aggregate classes that constitute the Contact class are:
ContactName
Zero or one. ML_STRING. The name of the contact. The contact
may either be an organization or a person. The type attribute
disambiguates the semantics.
Description
Zero or many. ML_STRING. A free-form description of this
contact. In the case of a person, this is often the
organizational title of the individual.
RegistryHandle
Zero or many. A handle name into the registry of the contact.
PostalAddress
Zero or one. The postal address of the contact.
Email
Zero or many. The email address of the contact.
Telephone
Zero or many. The telephone number of the contact.
Fax
Zero or one. The facsimile telephone number of the contact.
Timezone
Zero or one. TIMEZONE. The timezone in which the contact resides
formatted according to Section 2.9.
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Contact
Zero or many. A Contact instance contained within another Contact
instance inherits the values of the parent(s). This recursive
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 many. 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. This is not enforced in the IODEF schema as
there is no simple way to accomplish it.
The Contact class has five attributes:
role
Required. ENUM. Indicates the role the contact fulfills. This
attribute is defined as an enumerated list:
1. creator. The entity that generate the document.
2. admin. An administrative contact for a host or network.
3. tech. A technical contact for a host or network.
4. irt. The CSIRT involved in handling the incident.
5. cc. An entity that is to be kept informed about the handling
of the incident.
6. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-role
Optional. STRING. A means by which to extend the role attribute.
See Section 5.1.
type
Required. ENUM. Indicates the type of contact being described.
This attribute is defined as an enumerated list:
1. person. The information for this contact references an
individual.
2. organization. The information for this contact references an
organization.
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3. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.
restriction
Optional. ENUM. This attribute is defined in Section 3.2.
3.7.1. RegistryHandle Class
The RegistryHandle class represents a handle into an Internet
registry or community-specific database. The handle is specified in
the element content and the type attribute specifies the database.
+---------------------+
| RegistryHandle |
+---------------------+
| STRING |
| |
| ENUM registry |
| STRING ext-registry |
+---------------------+
Figure 8: The RegistryHandle Class
The RegistryHandle class has two attributes:
registry
Required. ENUM. The database to which the handle belongs. The
default value is 'local'. 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 IP Address Registry
5. ripe. Reseaux IP Europeens
6. afrinic. African Internet Numbers Registry
7. local. A database local to the CSIRT
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8. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-registry
Optional. STRING. A means by which to extend the registry
attribute. See Section 5.1.
3.7.2. PostalAddress Class
The PostalAddress class specifies a postal address formatted
according to the POSTAL data type (Section 2.11).
+---------------------+
| PostalAddress |
+---------------------+
| POSTAL |
| |
| ENUM meaning |
| ENUM lang |
+---------------------+
Figure 9: The PostalAddress Class
The PostalAddress class has two attributes:
meaning
Optional. ENUM. A free-form description of the element content.
lang
Required. ENUM. A valid language code per RFC 4646 [7]
constrained by the definition of "xs:language". The
interpretation of this code is described in Section 6.
3.7.3. Email Class
The Email class specifies an email address formatted according to
EMAIL data type (Section 2.14).
+--------------+
| Email |
+--------------+
| EMAIL |
| |
| ENUM meaning |
+--------------+
Figure 10: The Email Class
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The Email class has one attribute:
meaning
Optional. ENUM. A free-form description of the element content.
3.7.4. Telephone and Fax Classes
The Telephone and Fax classes specify a voice or fax telephone number
respectively, and are formatted according to PHONE data type
(Section 2.13).
+--------------------+
| {Telephone | Fax } |
+--------------------+
| PHONE |
| |
| ENUM meaning |
+--------------------+
Figure 11: The Telephone and Fax Classes
The Telephone class has one attribute:
meaning
Optional. ENUM. A free-form description of the element content
(e.g., hours of coverage for a given number).
3.8. Time Classes
The data model uses five different classes to represent a timestamp.
Their definition is identical, but each has a distinct name to convey
a difference in semantics.
The element content of each class is a timestamp formatted according
to the DATETIME data type (see Section 2.8).
+----------------------------------+
| {Start| End| Report| Detect}Time |
+----------------------------------+
| DATETIME |
+----------------------------------+
Figure 12: The Time Classes
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3.8.1. StartTime
The StartTime class represents the time the incident began.
3.8.2. EndTime
The EndTime class represents the time the incident ended.
3.8.3. DetectTime
The DetectTime class represents the time the first activity of the
incident was detected.
3.8.4. ReportTime
The ReportTime class represents the time the incident was reported.
This timestamp SHOULD coincide to the time at which the IODEF
document is generated.
3.8.5. DateTime
The DateTime class is a generic representation of a timestamp. Its
semantics should be inferred from the parent class in which it is
aggregated.
3.9. Method Class
The Method class describes the methodology used by the intruder to
perpetrate the events of the incident. This class consists of a list
of references describing the attack method and a free form
description of the technique.
+------------------+
| Method |
+------------------+
| ENUM restriction |<>--{0..*}--[ Reference ]
| |<>--{0..*}--[ Description ]
| |<>--{0..*}--[ AdditionalData ]
+------------------+
Figure 13: The Method Class
The Method class is composed of three aggregate classes.
Reference
Zero or many. A reference to a vulnerability, malware sample,
advisory, or analysis of an attack technique.
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Description
Zero or many. ML_STRING. A free-form text description of the
methodology used by the intruder.
AdditionalData
Zero or many. A mechanism by which to extend the data model.
Either an instance of the Reference or Description class MUST be
present.
The Method class has one attribute:
restriction
Optional. ENUM. This attribute is defined in Section 3.2.
3.9.1. Reference Class
The Reference class is a reference to a vulnerability, IDS alert,
malware sample, advisory, or attack technique. A reference consists
of a name, a URL to this reference, and an optional description.
+------------------+
| Reference |
+------------------+
| |<>----------[ ReferenceName ]
| |<>--{0..*}--[ URL ]
| |<>--{0..*}--[ Description ]
+------------------+
Figure 14: The Reference Class
The aggregate classes that constitute Reference:
ReferenceName
One. ML_STRING. Name of the reference.
URL
Zero or many. URL. A URL associated with the reference.
Description
Zero or many. ML_STRING. A free-form text description of this
reference.
3.10. Assessment Class
The Assessment class describes the technical and non-technical
repercussions of the incident on the CSIRT's constituency.
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This class was derived from the IDMEF[17].
+------------------+
| Assessment |
+------------------+
| ENUM occurrence |<>--{0..*}--[ Impact ]
| ENUM restriction |<>--{0..*}--[ TimeImpact ]
| |<>--{0..*}--[ MonetaryImpact ]
| |<>--{0..*}--[ Counter ]
| |<>--{0..1}--[ Confidence ]
| |<>--{0..*}--[ AdditionalData ]
+------------------+
Figure 15: Assessment Class
The aggregate classes that constitute Assessment are:
Impact
Zero or many. Technical impact of the incident on a network.
TimeImpact
Zero or many. Impact of the activity measured with respect to
time.
MonetaryImpact
Zero or many. Impact of the activity measured with respect to
financial loss.
Counter
Zero or more. A counter with which to summarize the magnitude of
the activity.
Confidence
Zero or one. An estimate of confidence in the assessment.
AdditionalData
Zero or many. A mechanism by which to extend the data model.
A least one instance of the possible three impact classes (i.e.,
Impact, TimeImpact, or MonetaryImpact) MUST be present.
The Assessment class has two attributes:
occurrence
Optional. ENUM. Specifies whether the assessment is describing
actual or potential outcomes. The default is "actual" and is
assumed if not specified.
Danyliw, et al. Standards Track [Page 26]
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1. actual. This assessment describes activity that has occurred.
2. potential. This assessment describes potential activity that
might occur.
restriction
Optional. ENUM. This attribute is defined in Section 3.2.
3.10.1. Impact Class
The Impact class allows for categorizing and describing the technical
impact of the incident on the network of an organization.
This class is based on the IDMEF [17].
+------------------+
| Impact |
+------------------+
| ML_STRING |
| |
| ENUM lang |
| ENUM severity |
| ENUM completion |
| ENUM type |
| STRING ext-type |
+------------------+
Figure 16: Impact Class
The element content will be a free-form textual description of the
impact.
The Impact class has five attributes:
lang
Required. ENUM. A valid language code per RFC 4646 [7]
constrained by the definition of "xs:language". The
interpretation of this code is described in Section 6.
severity
Optional. ENUM. An estimate of the relative severity of the
activity. The permitted values are shown below. There is no
default value.
Danyliw, et al. Standards Track [Page 27]
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1. low. Low severity
2. medium. Medium severity
3. high. High severity
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 malicious activity into incident
categories. The permitted values are shown below. The default
value is "other".
1. admin. Administrative privileges were attempted.
2. dos. A denial of service was attempted.
3. file. An action that impacts the integrity of a file or
database was attempted.
4. info-leak. An attempt was made to exfiltrate information.
5. misconfiguration. An attempt was made to exploit a mis-
configuration in a system.
6. policy. Activity violating site's policy was attempted.
7. recon. Reconnaissance activity was attempted.
8. social-engineering. A social engineering attack was
attempted.
9. user. User privileges were attempted.
10. unknown. The classification of this activity is unknown.
11. ext-value. An escape value used to extend this attribute.
See Section 5.1.
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ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.
3.10.2. 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 17: TimeImpact Class
The element content is a positive, floating point (REAL) number
specifying a unit of time. The duration and metric attributes will
imply the semantics of the element content.
The TimeImpact class has five attributes:
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 metric in which the time is
expressed. The permitted values are shown below. There is no
default value.
Danyliw, et al. Standards Track [Page 29]
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1. labor. Total staff-time to recovery from the activity (e.g.,
2 employees working 4 hours each would be 8 hours).
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. An escape value used to extend this attribute.
See Section 5.1.
ext-metric
Optional. STRING. A means by which to extend the metric
attribute. See Section 5.1.
duration
Required. ENUM. Defines a unit of time, that when combined with
the metric attribute, fully describes a metric of impact that will
be conveyed in the element content. The permitted values are
shown below. The default value is "hour".
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. An escape value used to extend this attribute.
See Section 5.1.
ext-duration
Optional. STRING. A means by which to extend the duration
attribute. See Section 5.1.
3.10.3. 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
Danyliw, et al. Standards Track [Page 30]
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productivity of the staff, or a tarnished reputation that will affect
future opportunities.
+------------------+
| MonetaryImpact |
+------------------+
| REAL |
| |
| ENUM severity |
| STRING currency |
+------------------+
Figure 18: MonetaryImpact Class
The element content is a positive, floating point number (REAL)
specifying a unit of currency described in the currency attribute.
The MonetaryImpact class has two attributes:
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
Required. STRING. Defines the currency in which the monetary
impact is expressed. The permitted values are defined in ISO
4217:2001, Codes for the representation of currencies and funds
[14]. There is no default value.
3.10.4. Confidence Class
The Confidence class represents a best estimate of the validity and
accuracy of the described impact (see Section 3.10) of the incident
activity. This estimate can be expressed as a category or a numeric
calculation.
This class if based upon the IDMEF [17]).
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+------------------+
| Confidence |
+------------------+
| REAL |
| |
| ENUM rating |
+------------------+
Figure 19: Confidence Class
The element content expresses a numerical assessment in the
confidence of the data when the value of the rating attribute is
"numeric". Otherwise, this element should be empty.
The Confidence class has one attribute.
rating
Required. ENUM. A rating of the analytical validity of the
specified Assessment. The permitted values are shown below.
There is no default value.
1. low. Low confidence in the validity.
2. medium. Medium confidence in the validity.
3. high. High confidence in the validity.
4. numeric. The element content contains a number that conveys
the confidence of the data. The semantics of this number
outside the scope of this specification.
3.11. 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 ]
| |
+------------------+
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Figure 20: The History Class
The class that constitutes History is:
HistoryItem
One or many. Entry in the history log of significant events or
actions performed by the involved parties.
The History class has one attribute:
restriction
Optional. ENUM. This attribute is defined in Section 3.2.
3.11.1. HistoryItem Class
The HistoryItem class is an entry in the History (Section 3.11) 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 description, but each can be categorized with the type
attribute.
+-------------------+
| HistoryItem |
+-------------------+
| ENUM restriction |<>----------[ DateTime ]
| ENUM action |<>--{0..1}--[ IncidentId ]
| STRING ext-action |<>--{0..1}--[ Contact ]
| |<>--{0..*}--[ Description ]
| |<>--{0..*}--[ AdditionalData ]
+-------------------+
Figure 21: HistoryItem Class
The aggregate classes that constitute HistoryItem are:
DateTime
One. Timestamp of this entry in the history log (e.g., when the
action described in the Description was taken).
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 incident
tracking number. When a single organization is maintaining the
log, this class can be ignored.
Danyliw, et al. Standards Track [Page 33]
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Contact
Zero or One. Provides contact information for the person that
performed the action documented in this class.
Description
Zero or many. ML_STRING. A free-form textual description of the
action or event.
AdditionalData
Zero or many. A mechanism by which to extend the data model.
The HistoryItem class has three attributes:
restriction
Optional. ENUM. This attribute has been defined in Section 3.2.
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 internal investigation, this attribute is identical
to the category 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 3.13.
ext-action
Optional. STRING. A means by which to extend the action
attribute. See Section 5.1.
3.12. EventData Class
The EventData class describes a particular event of the incident for
a given set of hosts or networks. This description includes the
systems from which the activity originated and those targeted, an
assessment of the techniques used by the intruder, the impact of the
activity on the organization, and any forensic evidence discovered.
Danyliw, et al. Standards Track [Page 34]
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+------------------+
| EventData |
+------------------+
| ENUM restriction |<>--{0..*}--[ Description ]
| |<>--{0..1}--[ DetectTime ]
| |<>--{0..1}--[ StartTime ]
| |<>--{0..1}--[ EndTime ]
| |<>--{0..*}--[ Contact ]
| |<>--{0..1}--[ Assessment ]
| |<>--{0..*}--[ Method ]
| |<>--{0..*}--[ Flow ]
| |<>--{0..*}--[ Expectation ]
| |<>--{0..1}--[ Record ]
| |<>--{0..*}--[ EventData ]
| |<>--{0..*}--[ AdditionalData ]
+------------------+
Figure 22: The EventData Class
The aggregate classes that constitute EventData are:
Description
Zero or more. ML_STRING. A free-form textual description of the
event.
DetectTime
Zero or one. The time the event was detected.
StartTime
Zero or one. The time the event started.
EndTime
Zero or one. The time the event ended.
Contact
Zero or more. Contact information for the parties involved in the
event.
Assessment
Zero or one. The impact of the event on the target and the
actions taken.
Method
Zero or more. The technique used by the intruder in the event.
Danyliw, et al. Standards Track [Page 35]
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Flow
Zero or more. A description of the systems or networks involved.
Expectation
Zero or more. The expected action to be performed by the
recipient for the described event.
Record
Zero or one. Supportive data (e.g., log files) that provides
additional information about the event.
EventData
Zero or more. EventData instances contained within another
EventData instance inherit the values of the parent(s); this
recursive definition can be used to group common data pertaining
to multiple events. When EventData elements are defined
recursively, only the leaf instances (those EventData instances
not containing other EventData instances) represent actual events.
AdditionalData
Zero or more. 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. This is not enforced in the IODEF schema as
there is no simple way to accomplish it.
The EventData class has one attribute:
restriction
Optional. ENUM. This attribute is defined in Section 3.2.
3.12.1. Relating the Incident and EventData Classes
There is substantial overlap 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 most common case,
the EventData class will provide more specific information for the
general description provided in the Incident class. However, it may
also be possible that the overall summarized information about the
incident conflicts with some individual information in an EventData
class when there is a substantial composition of various events in
the incident. In such a case, the interpretation of the more
specific EventData MUST supersede the more generic information
provided in IncidentData.
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3.12.2. Cardinality of EventData
The EventData class can be thought of as 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. With an instance of the EventData class, hosts
(i.e., System class) are grouped around these common properties.
The recursive definition (or instance property inheritance) of the
EventData class (the EventData class is aggregated into the EventData
class) provides a way to related information without requiring the
explicit use of unique attribute identifiers in the classes or
duplicating information. Instead, the relative depth (nesting) of a
class is used to group (relate) information.
For example, an EventData class might be used to describe two
machines involved in an incident. This description can be achieved
using multiple instances of the Flow class. It happens that there is
a common technical contact (i.e., Contact class) for these two
machines, but the impact (i.e., Assessment class) on them is
different. A depiction of the representation for this situation can
be found in Figure 23.
+------------------+
| EventData |
+------------------+
| |<>----[ Contact ]
| |
| |<>----[ EventData ]<>----[ Flow ]
| | [ ]<>----[ Assessment ]
| |
| |<>----[ EventData ]<>----[ Flow ]
| | [ ]<>----[ Assessment ]
+------------------+
Figure 23: Recursion in the EventData Class
3.13. Expectation Class
The Expectation class conveys to the recipient of the IODEF document
the actions the sender is requesting. The scope of the requested
action is limited to purview of the EventData class in which this
class is aggregated.
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+-------------------+
| Expectation |
+-------------------+
| ENUM restriction |<>--{0..*}--[ Description ]
| ENUM severity |<>--{0..1}--[ StartTime ]
| ENUM action |<>--{0..1}--[ EndTime ]
| STRING ext-action |<>--{0..1}--[ Contact ]
+-------------------+
Figure 24: The Expectation Class
The aggregate classes that constitute Expectation are:
Description
Zero or many. ML_STRING. A free-form description of the desired
action(s).
StartTime
Zero or one. The time at which the action should be performed. A
timestamp that is earlier than the ReportTime specified in the
Incident class denotes that the expectation should be fulfilled as
soon as possible. The absence of this element leaves the
execution of the expectation to the discretion of the recipient.
EndTime
Zero or one. The time by which the action should be completed.
If the action is not carried out by this time, it should no longer
be performed.
Contact
Zero or one. The expected actor for the action.
The Expectations class has four attributes:
restriction
Optional. ENUM. This attribute is defined in Section 3.2.
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
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action
Optional. ENUM. Classifies the type of action requested. This
attribute is an enumerated list with no default value.
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 systems(s) listed in the event.
6. block-host. Block traffic from the machine(s) listed as
sources 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.
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. remediate-other. Remediate the activity in a way other than
by rate limiting or blocking.
13. status-triage. Conveys receipts and the triaging of an
incident.
14. status-new-info. Conveys that new information was received
for this incident.
15. other. Perform some custom action described in the
Description class.
16. ext-value. An escape value used to extend this attribute.
See Section 5.1.
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ext-action
Optional. STRING. A means by which to extend the action
attribute. See Section 5.1.
3.14. Flow Class
The Flow class groups related the source and target hosts.
+------------------+
| Flow |
+------------------+
| |<>--{1..*}--[ System ]
+------------------+
Figure 25: The Flow Class
The aggregate class that constitutes Flow is:
System
One or More. A host or network involved in an event.
The Flow System class has no attributes.
3.15. System Class
The System class describes a system or network involved in an event.
The systems or networks represented by this class are categorized
according to the role they played in the incident through the
category attribute. The value of this category attribute dictates
the semantics of the aggregated classes in the System class. If the
category attribute has a value of "source", then the aggregated
classes denote the machine and service from which the activity is
originating. With a category attribute value of "target" or
"intermediary", then the machine or service is the one targeted in
the activity. A value of "sensor" dictates that this System was part
of an instrumentation to monitor the network.
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+---------------------+
| System |
+---------------------+
| ENUM restriction |<>----------[ Node ]
| ENUM category |<>--{0..*}--[ Service ]
| STRING ext-category |<>--{0..*}--[ OperatingSystem ]
| STRING interface |<>--{0..*}--[ Counter ]
| ENUM spoofed |<>--{0..*}--[ Description ]
| |<>--{0..*}--[ AdditionalData ]
+---------------------+
Figure 26: The System Class
The aggregate classes that constitute System are:
Node
One. A host or network involved in the incident.
Service
Zero or more. A network service running on the system.
OperatingSystem
Zero or one. The operating system running on the system.
Counter
Zero or more. A counter with which to summarize properties of
this host or network.
Description
Zero or more. ML_STRING. A free-form text description of the
System.
AdditionalData
Zero or many. A mechanism by which to extend the data model.
The System class has five attributes:
restriction
Optional. ENUM. This attribute is defined in Section 3.2.
category
Required. ENUM. Classifies the role the host or network played
in the incident. The possible values are:
1. source. The System was the source of the event.
2. target. The System was the target of the event.
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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
IODEF document exchange.
6. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-category
Optional. STRING. A means by which to extend the category
attribute. See Section 5.1.
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.
2. yes. The category attribute value is probably 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.
3.16. Node Class
The Node class names a system (e.g., PC, router) or network.
This class was derived from the IDMEF [17].
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+---------------+
| Node |
+---------------+
| |<>--{0..*}--[ NodeName ]
| |<>--{0..*}--[ Address ]
| |<>--{0..1}--[ Location ]
| |<>--{0..1}--[ DateTime ]
| |<>--{0..*}--[ NodeRole ]
| |<>--{0..*}--[ Counter ]
+---------------+
Figure 27: The Node Class
The aggregate classes that constitute Node are:
NodeName
Zero or more. ML_STRING. The name of the Node (e.g., fully
qualified domain name). This information MUST be provided if no
Address information is given.
Address
Zero or more. The hardware, network, or application address of
the Node. If a NodeName is not provided, at least one Address
MUST be specified.
Location
Zero or one. ML_STRING. A free-from description of the physical
location of the equipment.
DateTime
Zero or one. A timestamp of when the resolution between the name
and address was performed. This information SHOULD be provided if
both an Address and NodeName are specified.
NodeRole
Zero or more. The intended purpose of the Node.
Counter
Zero or more. A counter with which to summarizes properties of
this host or network.
3.16.1. Counter Class
The Counter class summarize multiple occurrences of some event, or
conveys counts or rates on various features (e.g., packets, sessions,
events).
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The value of the counter is the element content with its units
represented in the type attribute. A rate for a given feature can be
expressed by setting the duration attribute. The complete semantics
are entirely context dependent based on the class in which the
Counter is aggregated.
+---------------------+
| Counter |
+---------------------+
| REAL |
| |
| ENUM type |
| STRING ext-type |
| STRING meaning |
| ENUM duration |
| STRING ext-duration |
+---------------------+
Figure 28: The Counter Class
The Counter class has three attribute:
type
Required. ENUM. Specifies the units of the element content.
1. byte. Count of bytes.
2. packet. Count of packets.
3. flow. Count of flow (e.g., NetFlow records).
4. session. Count of sessions.
5. alert. Count of notifications generated by another system
(e.g., IDS or SIM).
6. message. Count of messages (e.g., mail messages).
7. event. Count of events.
8. host. Count of hosts.
9. site. Count of site.
10. organization. Count of organizations.
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11. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.
duration
Optional. ENUM. If present, the Counter class represents a rate
rather than a count over the entire event. In that case, this
attribute specifies the denominator of the rate (where the type
attribute specified the nominator). The possible values of this
attribute are defined in Section 3.10.2
ext-duration
Optional. STRING. A means by which to extend the duration
attribute. See Section 5.1.
3.16.2. Address Class
The Address class represents a hardware (layer-2), network (layer-3),
or application (layer-7) address.
This class was derived from the IDMEF [17].
+---------------------+
| Address |
+---------------------+
| ENUM category |
| STRING ext-category |
| STRING vlan-name |
| INTEGER vlan-num |
+---------------------+
Figure 29: The Address Class
The Address class has four attributes:
category
Required. ENUM. The type of address represented. The permitted
values for this attribute are shown below. The default value is
"ipv4-addr".
1. asn. Autonomous System Number
2. atm. Asynchronous Transfer Mode (ATM) address
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3. e-mail. Electronic mail address (RFC 822)
4. ipv4-addr. IPv4 host address in dotted-decimal notation
(a.b.c.d)
5. ipv4-net. IPv4 network address in dotted-decimal notation,
slash, significant bits (a.b.c.d/nn)
6. ipv4-net-mask. IPv4 network address in dotted-decimal
notation, slash, network mask in dotted-decimal notation
(a.b.c.d/w.x.y.z)
7. ipv6-addr. IPv6 host address
8. ipv6-net. IPv6 network address, slash, significant bits
9. ipv6-net-mask. IPv6 network address, slash, network mask
10. mac. Media Access Control (MAC) address
11. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-category
Optional. STRING. A means by which to extend the category
attribute. See Section 5.1.
vlan-name
Optional. STRING. The name of the Virtual LAN to which the
address belongs.
vlan-num
Optional. STRING. The number of the Virtual LAN to which the
address belongs.
3.16.3. NodeRole Class
The NodeRole class describes the intended function performed by a
particular host.
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+---------------------+
| NodeRole |
+---------------------+
| ENUM category |
| STRING ext-category |
| ENUM lang |
+---------------------+
Figure 30: The NodeRole Class
The NodeRole class has three attributes:
category
Required. ENUM. Functionality provided by a node.
1. client. Client computer
2. server-internal. Server with internal services
3. server-public. Server with public services
4. www. WWW server
5. mail. Mail server
6. messaging. Messaging server (e.g., NNTP, IRC, IM)
7. streaming. Streaming-media server
8. voice. Voice server (e.g., SIP, H.323)
9. file. File server (e.g., SMB, CVS, AFS)
10. ftp. FTP server
11. p2p. Peer-to-peer node
12. name. Name server (e.g., DNS, WINS)
13. directory. Directory server (e.g., LDAP, finger, whois)
14. credential. Credential server (e.g., domain controller,
Kerberos)
15. print. Print server
16. application. Application server
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17. database. Database server
18. infra. Infrastructure server (e.g., router, firewall, DHCP)
19. log. Logserver (e.g., syslog)
20. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-category
Optional. STRING. A means by which to extend the category
attribute. See Section 5.1.
lang
Required. ENUM. A valid language code per RFC 4646 [7]
constrained by the definition of "xs:language". The
interpretation of this code is described in Section 6.
3.17. Service Class
The Service class describes a network service of a host or network.
The service is identified by specific port or list of ports, along
with the application listening on that port.
When Service occurs as an aggregate class of a System that is a
source, then this service is the one from which activity of interest
is originating. Conversely, when Service occurs as an aggregate
class of a System that is a target, then that service is the one to
which activity of interest is directed.
This class was derived from the IDMEF [17].
+---------------------+
| Service |
+---------------------+
| INTEGER ip_protocol |<>--{0..1}--[ Port ]
| |<>--{0..1}--[ Portlist ]
| |<>--{0..1}--[ ProtoCode ]
| |<>--{0..1}--[ ProtoType ]
| |<>--{0..1}--[ ProtoFlags ]
| |<>--{0..1}--[ Application ]
+---------------------+
Figure 31: The Service Class
The aggregate classes that constitute Service are:
Danyliw, et al. Standards Track [Page 48]
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Port
Zero or one. INTEGER. A port number.
Portlist
Zero or one. PORTLIST. A list of port numbers formatted
according to Section 2.10.
ProtoCode
Zero or one. INTEGER. A layer-4 protocol-specific code field
(e.g., ICMP code field).
ProtoType
Zero or one. INTEGER. A layer-4 protocol specific type field
(e.g., ICMP type field).
ProtoFlags
Zero or one. INTEGER. A layer-4 protocol specific flag field
(e.g., TCP flag field).
Application
Zero or more. The application bound to the specified Port or
Portlist.
Either a Port or Portlist class MUST be specified for a given
instance of a Service class.
For a given source, System@type="source", a corresponding target,
System@type="target", maybe defined, or vice versa. When a Portlist
class is defined in the Service class of both the source and target
in a given instance of the Flow class, there MUST be symmetry in the
enumeration of the ports. Thus, if n-ports are listed for a source,
n-ports should be listed for the target. Likewise, the ports should
be listed in an identical sequence such that the n-th port in the
source corresponds to the n-th port of the target. This symmetry in
listing and sequencing of ports applies whether there are 1-to-1,
1-to-many, or many-to-many sources-to-targets. In the 1-to-many or
many-to-many, the exact order in which the System classes are
enumerated in the Flow class is significant.
The Service class has one attribute:
ip_protocol
Required. INTEGER. The IANA protocol number.
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3.17.1. Application Class
The Application class describes an application running on a System
providing a Service.
+--------------------+
| Application |
+--------------------+
| STRING swid |<>--{0..1}--[ URL ]
| STRING configid |
| STRING vendor |
| STRING family |
| STRING name |
| STRING version |
| STRING patch |
+--------------------+
Figure 32: The Application Class
The aggregate class that constitutes Application is:
URL
Zero or one. URL. A URL describing the application.
The Application class has seven attributes:
swid
Optional. STRING. An identifier that can be used to reference
this software.
configid
Optional. STRING. An identifier that can be used to reference a
particular configuration of this software.
vendor
Optional. STRING. Vendor name of the software.
family
Optional. STRING. Family of the software.
name
Optional. STRING. Name of the software.
version
Optional. STRING. Version of the software.
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patch
Optional. STRING. Patch or service pack level of the software.
3.18. OperatingSystem Class
The OperatingSystem class describes the operating system running on a
System. The definition is identical to the Application class
(Section 3.17.1).
3.19. Record Class
The Record class is a container class for log and audit data that
provides supportive information about the incident. The source of
this data will often be the output of monitoring tools. These logs
should substantiate the activity described in the document.
+------------------+
| Record |
+------------------+
| ENUM restriction |<>--{1..*}--[ RecordData ]
+------------------+
Figure 33: Record Class
The aggregate class that constitutes Record is:
RecordData
One or more. Log or audit data generated by a particular type of
sensor. Separate instances of the RecordData class SHOULD be used
for each sensor type.
The Record class has one attribute:
restriction
Optional. ENUM. This attribute has been defined in Section 3.2.
3.19.1. RecordData Class
The RecordData class groups log or audit data from a given sensor
(e.g., IDS, firewall log) and provides a way to annotate the output.
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+------------------+
| RecordData |
+------------------+
| ENUM restriction |<>--{0..1}--[ DateTime ]
| |<>--{0..*}--[ Description ]
| |<>--{0..1}--[ Application ]
| |<>--{0..*}--[ RecordPattern ]
| |<>--{1..*}--[ RecordItem ]
| |<>--{0..*}--[ AdditionalData ]
+------------------+
Figure 34: The RecordData Class
The aggregate classes that constitutes RecordData is:
DateTime
Zero or one. Timestamp of the RecordItem data.
Description
Zero or more. ML_STRING. Free-form textual description of the
provided RecordItem data. At minimum, this description should
convey the significance of the provided RecordItem data.
Application
Zero or one. Information about the sensor used to generate the
RecordItem data.
RecordPattern
Zero or more. A search string to precisely find the relevant data
in a RecordItem.
RecordItem
One or more. Log, audit, or forensic data.
AdditionalData
Zero or one. An extension mechanism for data not explicitly
represented in the data model.
The RecordData class has one attribute:
restriction
Optional. ENUM. This attribute has been defined in Section 3.2.
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3.19.2. RecordPattern Class
The RecordPattern class describes where in the content of the
RecordItem 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.
+-----------------------+
| RecordPattern |
+-----------------------+
| STRING |
| |
| ENUM type |
| STRING ext-type |
| INTEGER offset |
| ENUM offsetunit |
| STRING ext-offsetunit |
| INTEGER instance |
+-----------------------+
Figure 35: The RecordPattern Class
The specific pattern to search with in the RecordItem is defined in
the body of the element. It is further annotated by four attributes:
type
Required. ENUM. Describes the type of pattern being specified in
the element content. The default is "regex".
1. regex. regular expression, per Appendix F of [3].
2. binary. Binhex encoded binary pattern, per the HEXBIN data
type.
3. xpath. XML Path (XPath) [5]
4. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.
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".
1. line. Offset is a count of lines.
2. binary. Offset is a count of bytes.
3. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-offsetunit
Optional. STRING. A means by which to extend the offsetunit
attribute. See Section 5.1.
instance
Optional. INTEGER. Number of types to apply the specified
pattern.
3.19.3. RecordItem Class
The RecordItem class provides a way to incorporate relevant logs,
audit trails, or forensic data to support the conclusions made during
the course of analyzing the incident. The class supports both the
direct encapsulation of the data, as well as, provides primitives to
reference data stored elsewhere.
This class is identical to AdditionalData class (Section 3.6).
4. Processing Considerations
This section defines additional requirements on creating and parsing
IODEF documents.
4.1. Encoding
Every IODEF document MUST begin with an XML declaration, and MUST
specify the XML version used. If UTF-8 encoding is not used, the
character encoding MUST also be explicitly specified. The IODEF
conforms to all XML data encoding conventions and constraints.
The XML declaration with no character encoding will read as follows:
< ?xml version="1.0" ? >
When a character encoding is specified, the XML declaration will read
like the following:
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< ?xml version="1.0" encoding="charset" ? >
Where "charset" is the name of the character encoding as registered
with the Internet Assigned Numbers Authority (IANA), see [9].
The following characters have special meaning in XML and MUST be
escaped with their entity reference equivalent: "&", "<", ">", "\""
(double quotation mark), and "'" (apostrophe). These entity
references are "&", "<", ">", """, and "'"
respectively.
4.2. IODEF Namespace
The IODEF schema declares a namespace of
"urn:ietf:params:xml:ns:iodef-1.0" and registers it per [4]. Each
IODEF document SHOULD 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
The IODEF documents MUST be well-formed XML and SHOULD be validated
against the schema described in Section 8. However, mere conformance
to the schema is not sufficient for a semantically valid IODEF
document. There is additional specification in the text of Section 3
that cannot be readily encoded in the schema and it must also be
considered by an IODEF parser. The following is a list of
discrepancies in what is more strictly specified in the normative
text (Section 3), but not enforced in the IODEF schema:
o The elements or attributes that are defined as POSTAL, NAME,
PHONE, and EMAIL data-types are implemented as "xs:string", but
more rigid formatting requirements are specified in the text.
o The IODEF-Document@lang and MLStringType@lang attributes are
declared as an "xs:language" that constrains values with a regular
expression. However, the value of this attribute still needs to
be validated against the list of possible enumerated values is
defined in [7].
o The MonetaryImpact@currency attribute is declared as an "xs:
string", but the list of valid values as defined in [14].
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o All of the aggregated classes Contact and EventData are optional
in the schema, but at least one of these aggregated classes MUST
be present.
o There are multiple conventions that can be used to categorize a
system using the NodeRole class or to specify software with the
Application and OperatingSystem classes. IODEF parsers MUST
accept incident reports that do not use these fields in accordance
with local conventions.
o The Confidence@rating attribute determines whether the element
content of Confidence should be empty.
o The Address@type attribute determines the format of the element
content.
o The attributes AdditionalData@dtype and RecordItem@dtype derived
from iodef:ExtensionType determine the semantics and formatting of
the element content.
o Symmetry in the enumerated ports of a Portlist class is required
between sources and targets. See Section 3.17.
5. Extending the IODEF
In order to support the changing activity of CSIRTS, the IODEF data
model will need to evolve along with them. This section discusses
how new data elements that have no current representation in the data
model can be incorporated into the IODEF. These techniques are
designed so that adding new data will not require a change to the
IODEF schema. With proven value, well documented extensions can be
incorporated into future versions of the specification. However,
this approach also supports private extensions relevant only to a
closed consortium.
5.1. Extending the Enumerated Values of Attributes
The data model supports a means by which to add new enumerated values
to an attribute. For each attribute that supports this extension
technique, there is a corresponding attribute in the same element
whose name is identical, less a prefix of "ext-". This special
attribute is referred to as the extension attribute, and 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, and therefore many extension, attributes.
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In addition to a corresponding extension attribute, each extensible
attribute has "ext-value" as one its possible values. This
particular value serves as an escape sequence and has no valid
meaning.
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, an extended instance of the type attribute of the Impact
class would look as follows:
A given extension attribute MUST NOT be set unless the corresponding
extensible attribute has been set to "ext-value".
5.2. Extending Classes
The classes of the data model can be extended only through the use of
the AdditionalData and RecordItem classes. These container classes,
collectively referred to as the extensible classes, are implemented
with the iodef:ExtensionType data type in the schema. 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 a few of the more
complicated 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 of extensible class to the desired value,
and
2. Set the dtype attribute to correspond to the data type of the
element content.
The following guidelines exist for extensions using 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-".
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3. It is RECOMMENDED that extension schemas follow the naming
convention of the IODEF data model. The names of all elements
are capitalized. For composed names, a capital letter is used
for each word. Attribute names are lower case.
4. When a parser encounters an IODEF document with an extension it
does not understand, this extension MUST be ignored (and not
processed), but the remainder of the document MUST be processed.
Parsers will be able to identify these extensions for which they
have no processing logic through the namespace declaration.
Parsers that encounter an unrecognized element in a namespace
that they do support SHOULD reject the document as a syntax
error.
5. Implementations SHOULD NOT download schemas at runtime due to the
security implications, and extensions MUST NOT be required to
provide a resolvable location of their schema.
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.
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...
Field that could not be represented elsewhere
6. Internationalization Issues
Internationalization and localization is of specific concern to the
IODEF, since it is only through collaboration, often across language
barriers, that certain incidents be resolved. The IODEF supports
this goal by depending on XML constructs, and through explicit design
choices in the data model.
Since IODEF is implemented as an XML Schema, it implicitly supports
all the different character encodings, such as UTF-8 and UTF-16,
possible with XML. Additionally, each IODEF document MUST specify
the language in which their contents are encoded. The language can
be specified with the attribute "xml:lang" (per Section 2.12 of [1])
in the top-level element (i.e., IODEF-Document@lang) and letting all
other elements inherit that definition. All IODEF classes with a
free-form text definition (i.e., all those defined of type iodef:
MLStringType) can also specify a language different from the rest of
the document. The valid language codes for the "xml:lang" attribute
are described in RFC 4646 [7].
The data model supports multiple translations of free-form text. In
the places where free-text is used for descriptive purposes, the
given class always has a one-to-many cardinality to its parent (e.g.,
Description class). The intent is to allow the identical text to be
encoded in different instances of the same class, but each being in a
different language. This approach allows an IODEF document author to
send recipients speaking different languages an identical document.
The IODEF parser SHOULD extract the appropriate language relevant to
the recipient.
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While the intent of the data model is to provide internationalization
and localization, the intent is not to do so at the detriment of
interoperability. While the IODEF does support 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 text based data elements are
written in a language unfamiliar to the analyst.
7. Examples
This section provides examples of an incident encoded in the IODEF.
These examples do not necessarily represent the only way to encode a
particular incident.
7.1. Worm
An example of a CSIRT reporting an instance of the Code Red worm.
< ?xml version="1.0" encoding="UTF-8"? >
1894932001-09-13T23:19:24+00:00Host sending out Code Red probesExample.com CSIRTexample-comcontact@csirt.example.com
192.0.2.200
57
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192.0.2.16/28
802001-09-13T18:11:21+02:00Web-server logs
192.0.2.1 - - [13/Sep/2001:18:11:21 +0200] "GET /default.ida?
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
http://mylogs.example.com/logs/httpd_access2001-09-14T08:19:01+00:00Notification sent to
constituency-contact@192.0.2.200
7.2. Reconnaissance
An example of a CSIRT reporting a scanning activity.
< ?xml version="1.0" encoding="UTF-8" ? >
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593342006-08-02T05:54:02-05:00nmaphttp://nmap.toolsite.example.comCSIRT for example.comcontact@csirt.example.com+1 412 555 12345Joe Smithsmith@csirt.example.com
192.0.2.200
60524,60526,60527,60531
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192.0.2.201
137-139,445
192.0.2.240
192.0.2.64/28
445
7.3. Bot-Net Reporting
An example of a CSIRT reporting a bot-network.
< ?xml version="1.0" encoding="UTF-8" ? >
9087112006-06-08T05:44:53-05:00Large bot-net
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GT BotCA-2003-22http://www.cert.org/advisories/CA-2003-22.htmlRoot compromise via this IE vulnerability to
install the GT BotJoe Smithjsmith@csirt.example.comThese hosts are compromised and acting as bots
communicating with irc.example.com.
192.0.2.1
10000bot
192.0.2.3
250000botirc.example.com
192.0.2.20
2006-06-08T01:01:03-05:00
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IRC server on #give-me-cmd channelConfirm the source and take machines off-line and
remediate
7.4. Watch List
An example of a CSIRT conveying a watch-list.
< ?xml version="1.0" encoding="UTF-8" ? >
9087112006-08-01T00:00:00-05:00Watch-list of known bad IPs or networksCSIRT for example.comcontact@csirt.example.com
192.0.2.53
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Source of numerous attacks
192.0.2.16/28
Source of heavy scanning over past 1-month
192.0.2.241
C2 IRC server
8. The IODEF Schema
< ?xml version="1.0" encoding="UTF-8"? >
Incident Object Description Exchange Format v1.00, see RFC 5070
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9. Security Considerations
The IODEF data model itself does not directly introduce security
issues. Rather, it simply defines a representation for incident
information. As the data encoded by the IODEF might be considered
privacy sensitive by the parties exchanging the information or by
those described by it, care needs to be taken in ensuring the
appropriate disclosure during both document exchange and subsequent
processing. The former must be handled by a messaging format, but
the latter risk must be addressed by the systems that process, store,
and archive IODEF documents and information derived from them.
The contents of an IODEF document may include a request for action or
an IODEF parser may independently have logic to take certain actions
based on information that it finds. For this reason, care must be
taken by the parser to properly authenticate the recipient of the
document and ascribe an appropriate confidence to the data prior to
action.
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 [18] and its associated transport
binding IODEF/RID over SOAP [19] provide such security.
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. The issue of
enforcement is not a technical problem.
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10. IANA Considerations
This document uses URNs to describe an XML namespace and schema
conforming to a registry mechanism described in [15]
Registration for the IODEF namespace:
o URI: urn:ietf:params:xml:ns:iodef-1.0
o Registrant Contact: See the first author of 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-1.0
o Registrant Contact: See the first author of the "Author's Address"
section of this document.
o XML: See the "IODEF Schema" in Section 8 of this document.
11. Acknowledgments
The following groups and individuals, listed alphabetically,
contributed substantially to this document and should be recognized
for their efforts.
o Patrick Cain, Cooper-Cain Group, Inc.
o The eCSIRT.net Project
o The Incident Object Description and Exchange Format Working-Group
of the TERENA task-force (TF-CSIRT)
o Glenn Mansfield Keeni, Cyber Solutions, Inc.
o Hiroyuki Kido, NARA Institute of Science and Technology
o Kathleen Moriarty, MIT Lincoln Laboratory
o Brian Trammell, CERT/NetSA
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12. References
12.1. Normative References
[1] World Wide Web Consortium, "Extensible Markup Language (XML)
1.0 (Second Edition)", W3C Recommendation , October 2000,
.
[2] World Wide Web Consortium, "XML XML Schema Part 1: Structures
Second Edition", W3C Recommendation , October 2004,
.
[3] World Wide Web Consortium, "XML Schema Part 2: Datatypes Second
Edition", W3C Recommendation , October 2004,
.
[4] World Wide Web Consortium, "Namespaces in XML", W3C
Recommendation , January 1999,
.
[5] World Wide Web Consortium, "XML Path Language (XPath) 2.0", W3C
Candidate Recommendation , June 2006,
.
[6] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", RFC 2119, March 1997.
[7] Philips, A. and M. Davis, "Tags for Identifying of Languages",
RFC 4646, September 2006.
[8] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", RFC 3986,
January 2005`.
[9] Freed, N. and J. Postel, "IANA Charset Registration
Procedures", BCP 2978, October 2000.
[10] Sciberras, A., "Schema for User Applications", RFC 4519,
June 2006.
[11] Resnick, P., "Internet Message Format", RFC 2822, April 2001.
[12] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, July 2002.
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[13] International Organization for Standardization, "International
Standard: Data elements and interchange formats - Information
interchange - Representation of dates and times", ISO 8601,
Second Edition, December 2000.
[14] International Organization for Standardization, "International
Standard: Codes for the representation of currencies and funds,
ISO 4217:2001", ISO 4217:2001, August 2001.
[15] Mealling, M., "The IETF XML Registry", RFC 3688, January 2004.
12.2. Informative References
[16] Keeni, G., Demchenko, Y., and R. Danyliw, "Requirements for the
Format for Incident Information Exchange (FINE)", Work
in Progress, June 2006.
[17] Debar, H., Curry, D., Debar, H., and B. Feinstein, "Intrusion
Detection Message Exchange Format", RFC 4765, March 2007.
[18] Moriarty, K., "Real-time Inter-network Defense", Work
in Progress, April 2007.
[19] Moriarty, K. and B. Trammell, "IODEF/RID over SOAP", Work
in Progress, April 2007.
[20] Shafranovich, Y., "Common Format and MIME Type for Comma-
Separated Values (CSV) File", RFC 4180, October 2005.
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Authors' Addresses
Roman Danyliw
CERT - Software Engineering Institute
Pittsburgh, PA
USA
EMail: rdd@cert.org
Jan Meijer
EMail: jan@flyingcloggies.nl
Yuri Demchenko
University of Amsterdam
Amsterdam
Netherlands
EMail: demch@chello.nl
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Full Copyright Statement
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contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
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"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
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