| MILE Working Group | T. Takahashi |
| Internet-Draft | NICT |
| Intended status: Standards Track | K. Landfield |
| McAfee | |
| T. Millar | |
| USCERT | |
| Y. Kadobayashi | |
| NAIST | |
| Jan 14, 2014 |
IODEF-extension for structured cybersecurity information
draft-ietf-mile-sci-13.txt
This document extends the Incident Object Description Exchange Format (IODEF) defined in RFC 5070 [RFC5070] to exchange enriched cybersecurity information among security experts at organizations and facilitates their operations. It provides a well-defined pattern to consistently embed structured information, such as identifier- and XML-based information.
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."
Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
The number of incidents in cyber society is growing day by day. Incident information needs to be reported, exchanged, and shared among organizations in order to cope with the situation. IODEF is one of the tools already in use that enables such an exchange.
To more efficiently run security operations, information exchanged between organizations needs to be machine readable. IODEF provides a means to describe the incident information, but it often needs to include various non-structured types of incident-related data in order to convey more specific details about what is occurring. Further structure within IODEF increases the machine-readability of the document thus providing a means for better automating certain security operations.
Within the security community there exist various means for specifying structured descriptions of cybersecurity information such as [CAPEC][CCE][CCSS][CEE][CPE][CVE][CVRF][CVSS][CWE][CWSS][MAEC] [OCIL][OVAL][SCAP][XCCDF]. In this context, cybersecurity information encompasses a broad range of structured data representation types that may be used to assess or report on the security posture of an asset or set of assets. Such structured descriptions facilitates a better understanding of an incident while enabling more streamlined automated security operations. Because of this, it would be beneficial to embed and convey these types of information inside IODEF documents.
This document extends IODEF to embed and convey various types of structured information. Since IODEF defines a flexible and extensible format and supports a granular level of specificity, this document defines an extension to IODEF instead of defining a new report format. For clarity, and to eliminate duplication, only the additional structures necessary for describing the exchange of such structured information are provided.
The terminology used in this document follows the one defined in RFC 5070 [RFC5070].
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 RFC 2119 [RFC2119].
To maintain awareness of the continually changing security threat landscape, organization needs to exchange cybersecurity information, which includes the following information: attack pattern, platform information, vulnerability and weakness, countermeasure instruction, computer event logs, and severity assessments. IODEF provides a scheme to describe and exchange such information among interested parties. However, it does not define the detailed formats to specify such information.
There already exists structured and detailed formats for describing these types of information that can be used in facilitating such an exchange. They include [CAPEC][CCE][CCSS][CEE][CPE] [CVE][CVRF][CVSS][CWE][CWSS][MAEC][OCIL][OVAL][SCAP][XCCDF]. By embedding them into the IODEF document, the document can convey more detailed context information to the receivers, and the document can be easily reused.
The use of structured information formats facilitates more advanced security operations on the receiver side. Since the information is machine readable, the data can be processed by computers thus allowing better automation of security operations.
For instance, an organization wishing to report a security incident wants to describe what vulnerability was exploited. In this case the sender can simply use IODEF, where an XML-based [XML1.0] attack pattern record that follows the syntax and vocabulary defined by an industry specification is embedded, instead of describing everything in free form text. The receiver can identify the needed details of the attack pattern by looking up some of the XML tags defined by the specification. The receiver can accumulate the attack pattern record in its database and could distribute it to the interested parties as needed, all without requiring human interventions.
In another example, an administrator is investigating an incident and detected a configuration problem that he wishes to share with a partner organization to prevent the same event from occurring. He accesses configuration information in an internal repository that was gathered prior to the initial attack specific to a new vulnerability alert to confirm the configuration was in fact vulnerable. He uses this information to automatically generate an XML-based software configuration description, embed it in an IODEF document, and send the resulting IODEF document to the partner organization.
This document extends IODEF to embed structured information by introducing new classes that can be embedded consistently inside an IODEF document as element contents of the AdditionalData and RecordItem classes.
This extension embeds structured cybersecurity information defined by other specifications. The list of supported specifications is managed by IANA, and this document defines the needed fields for the list's entry.
Each entry has namespace [XMLNames], specification name, version, reference URI, and applicable classes for each specification. Arbitrary URIs that may help readers to understand the specification could be embedded inside the Reference URI field, but it is recommended that standard/informational URI describing the specification is prepared and is embedded here.
The initial IANA table has only one entry, as below.
Namespace: urn:ietf:params:xml:ns:mile:mmdef:1.2
Specification Name: Malware Metadata Exchange Format
Version: 1.2
Reference URI: http://standards.ieee.org/develop
/indconn/icsg/mmdef.html,
http://grouper.ieee.org/groups
/malware/malwg/Schema1.2/
Applicable Classes: AttackPattern
Note that the specification was developed by The Institute of Electrical and Electronics Engineers, Incorporated (IEEE), through the Industry Connections Security Group (ICSG) of its Standards Association.
The table is to be managed by IANA following the allocation policy specified in Section 7.
The SpecID attributes of extension classes [ExtensionClasses] must allow the values of the specifications' namespace fields, but otherwise, implementations are not required to support all specifications of the IANA table and may choose which specifications to support, though the specification listed in the initial table needs to be minimally supported, as described in Section 5. In case an implementation received a data it does not support, it may expand its functionality by looking up the IANA table or notify the sender of its inability to parse the data. Note that the look-up could be done manually or automatically, but automatic download of data from IANA's website is not recommended since it is not designed for mass retrieval of data by multiple devices.
This extension inherits all of the data types defined in the IODEF data model. One data type is added: XMLDATA. An embedded XML data is represented by the XMLDATA data type. This type is defined as the extension to the iodef:ExtensionType [RFC5070], whose dtype attribute is set to "xml".
This document defines eight extension classes, namely AttackPattern, Platform, Vulnerability, Scoring, Weakness, EventReport, Verification and Remediation. Figure 1 describes the relationships between the IODEF Incident class [RFC5070] and the newly defined classes. It is expressed in Unified Modeling Language (UML) syntax as with the RFC 5070 [RFC5070]. The UML representation is for illustrative purposes only; elements are specified in XML as defined in Section 5.2.
+---------------+
| Incident |
+---------------+
| ENUM purpose |<>---------[IncidentID]
| STRING |<>--{0..1}-[AlternativeID]
| ext-purpose |<>--{0..1}-[RelatedActivity]
| ENUM lang |<>--{0..1}-[DetectTime]
| ENUM |<>--{0..1}-[StartTime]
| restriction |<>--{0..1}-[EndTime]
| |<>---------[ReportTime]
| |<>--{0..*}-[Description]
| |<>--{1..*}-[Assessment]
| |<>--{0..*}-[Method]
| | |<>--{0..*}-[AdditionalData]
| | |<>--{0..*}-[AttackPattern]
| | |<>--{0..*}-[Vulnerability]
| | |<>--{0..*}-[Weakness]
| |<>--{1..*}-[Contact]
| |<>--{0..*}-[EventData]
| | |<>--{0..*}-[Flow]
| | | |<>--{1..*}-[System]
| | | |<>--{0..*}-[AdditionalData]
| | | |<>--{0..*}-[Platform]
| | |<>--{0..*}-[Expectation]
| | |<>--{0..1}-[Record]
| | |<>--{1..*}-[RecordData]
| | |<>--{1..*}-[RecordItem]
| | |<>--{0..*}-[EventReport]
| |<>--{0..1}-[History]
| |<>--{0..*}-[AdditionalData]
| | |<>--{0..*}-[Verification]
| | |<>--{0..*}-[Remediation]
+---------------+
Figure 1: Incident class
Figure 2 shows the basic structure of the extension classes. Some of the extension classes have extra elements as defined in Section 4.5, but the basic structure is the same.
+---------------------+ | New Class Name | +---------------------+ | ENUM SpecID |<>--(0..*)-[ RawData ] | STRING ext-SpecID |<>--(0..*)-[ Reference ] | STRING ContentID | +---------------------+
Figure 2: Basic Structure
Three attributes are defined as below.
Likewise, three elements are defined as below.
Though ContentID, RawData, and Reference are optional attribute and elements, one of them MUST be used to convey structured information. Note that only one of them SHOULD be used to avoid confusing the receiver.
This document defines the following seven extension classes.
An AttackPattern is an extension class to the Incident.Method.AdditionalData element with a dtype of "xml". It describes attack patterns of incidents or events. It is RECOMMENDED that Method class contain the extension elements whenever available. An AttackPattern class is structured as follows.
+---------------------+ | AttackPattern | +---------------------+ | ENUM SpecID |<>--(0..*)-[ RawData ] | STRING ext-SpecID |<>--(0..*)-[ Reference ] | STRING ContentID |<>--(0..*)-[ Platform ] +---------------------+
Figure 3: AttackPattern class
This class has the following attributes.
Likewise, this class has the following elements.
A Platform is an extension class that identifies a software platform. It is RECOMMENDED that AttackPattern, Vulnerability, Weakness, and System classes contain the extension elements whenever available. A Platform element is structured as follows.
+---------------------+ | Platform | +---------------------+ | ENUM SpecID |<>--(0..*)-[ RawData ] | STRING ext-SpecID |<>--(0..*)-[ Reference ] | STRING ContentID | +---------------------+
Figure 4: Platform class
This class has the following attributes.
Likewise, this class has the following elements.
A Vulnerability is an extension class to the Incident.Method.AdditionalData element with a dtype of "xml". The extension describes the vulnerabilities that are exposed or were exploited in incidents. It is RECOMMENDED that Method class contain the extension elements whenever available. A Vulnerability element is structured as follows.
+---------------------+ | Vulnerability | +---------------------+ | ENUM SpecID |<>--(0..*)-[ RawData ] | STRING ext-SpecID |<>--(0..*)-[ Reference ] | STRING ContentID |<>--(0..*)-[ Platform ] | |<>--(0..*)-[ Scoring ] +---------------------+
Figure 5: Vulnerability class
This class has the following attributes.
Likewise, this class has the following elements.
A Scoring is an extension class that describes the severity scores in terms of security. It is RECOMMENDED that Vulnerability and Weakness classes contain the extension elements whenever available. A Scoring class is structured as follows.
+---------------------+ | Scoring | +---------------------+ | ENUM SpecID |<>--(0..*)-[ RawData ] | STRING ext-SpecID |<>--(0..*)-[ Reference ] | STRING ContentID | +---------------------+
Figure 6: Scoring class
This class has two attributes.
Likewise, this class has the following elements.
A Weakness is an extension class to the Incident.Method.AdditionalData element with a dtype of "xml". The extension describes the weakness types that are exposed or were exploited in incidents. It is RECOMMENDED that Method class contain the extension elements whenever available. A Weakness element is structured as follows.
+---------------------+ | Weakness | +---------------------+ | ENUM SpecID |<>--(0..*)-[ RawData ] | STRING ext-SpecID |<>--(0..*)-[ Reference ] | STRING ContentID |<>--(0..*)-[ Platform ] | |<>--(0..*)-[ Scoring ] +---------------------+
Figure 7: Weakness class
This class has the following attributes.
Likewise, this class has the following elements.
An EventReport is an extension class to the Incident.EventData.Record.RecordData.RecordItem element with a dtype of "xml". The extension embeds structured event reports. It is RECOMMENDED that RecordItem class contain the extension elements whenever available. An EventReport element is structured as follows.
+---------------------+ | EventReport | +---------------------+ | ENUM SpecID |<>--(0..*)-[ RawData ] | STRING ext-SpecID |<>--(0..*)-[ Reference ] | STRING ContentID | +---------------------+
Figure 8: EventReport class
This class has the following attributes.
Likewise, this class has the following elements.
A Verification is an extension class to the Incident.AdditionalData element with a dtype of "xml". The extension elements describes information on verifying security, e.g., checklist, to cope with incidents. It is RECOMMENDED that Incident class contain the extension elements whenever available. A Verification class is structured as follows.
+---------------------+ | Verification | +---------------------+ | ENUM SpecID |<>--(0..*)-[ RawData ] | STRING ext-SpecID |<>--(0..*)-[ Reference ] | STRING ContentID | +---------------------+
Figure 9: Verification class
This class has the following attributes.
Likewise, this class has the following elements.
A Remediation is an extension class to the Incident.AdditionalData element with a dtype of "xml". The extension elements describes incident remediation information including instructions. It is RECOMMENDED that Incident class contain the extension elements whenever available. A Remediation class is structured as follows.
+---------------------+ | Remediation | +---------------------+ | ENUM SpecID |<>--(0..*)-[ RawData ] | STRING ext-SpecID |<>--(0..*)-[ Reference ] | String ContentID | +---------------------+
Figure 10: Remediation class
This class has the following attributes.
Likewise, this class has the following elements.
The implementation of this document MUST be capable of sending and receiving the XML conforming to the specification listed in the initial IANA table described in Section 4.1 without error. An SCI document is an XML document that MUST be well-formed and MUST be valid according to schemata, including extension schemata, available to the validator and applicable to the XML document. Note that the receiver can look up the namespace in the IANA table to understand what specifications the embedded XML documents follows.
For the purpose of facilitating the understanding of mandatory to implement features, the following subsections provide an XML conformant to this document, and a schema for that.
An example IODEF document for checking implementation's MTI conformity is provided here. The document carries MMDEF metadata. Note that the metadata is generated by genMMDEF [MMDEF] with EICAR [EICAR] files.
<?xml version="1.0" encoding="UTF-8"?>
<IODEF-Document version="1.00" lang="en"
xmlns="urn:ietf:params:xml:ns:iodef-1.0"
xmlns:iodef="urn:ietf:params:xml:ns:iodef-1.0"
xmlns:iodef-sci="urn:ietf:params:xml:ns:iodef-sci-1.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<Incident purpose="reporting">
<IncidentID name="iodef-sci.example.com">189493</IncidentID>
<ReportTime>2013-06-18T23:19:24+00:00</ReportTime>
<Description>a candidate security incident</Description>
<Assessment>
<Impact completion="failed" type="admin" />
</Assessment>
<Method>
<Description>A candidate attack event</Description>
<AdditionalData dtype="xml">
<iodef-sci:AttackPattern
SpecID="http://xml/metadataSharing.xsd">
<iodef-sci:RawData dtype="xml">
<malwareMetaData xmlns="http://xml/metadataSharing.xsd"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xml/metadataSharing.xsd
file:metadataSharing.xsd" version="1.200000" id="10000">
<company>N/A</company>
<author>MMDEF Generation Script</author>
<comment>Test MMDEF v1.2 file generated using genMMDEF
</comment>
<timestamp>2013-03-23T15:12:50.726000</timestamp>
<objects>
<file id="6ce6f415d8475545be5ba114f208b0ff">
<md5>6ce6f415d8475545be5ba114f208b0ff</md5>
<sha1>da39a3ee5e6b4b0d3255bfef95601890afd80709</sha1>
<sha256>e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca4
95991b7852b855</sha256>
<sha512>cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83
f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b9
31bd47417a81a538327af927da3e</sha512>
<size>184</size>
<filename>eicar_com.zip</filename>
<MIMEType>application/zip</MIMEType>
</file>
<file id="44d88612fea8a8f36de82e1278abb02f">
<md5>44d88612fea8a8f36de82e1278abb02f</md5>
<sha1>3395856ce81f2b7382dee72602f798b642f14140</sha1>
<sha256>275a021bbfb6489e54d471899f7db9d1663fc695ec2fe2a2c4
538aabf651fd0f</sha256>
<sha512>cc805d5fab1fd71a4ab352a9c533e65fb2d5b885518f4e565e
68847223b8e6b85cb48f3afad842726d99239c9e36505c64b0
dc9a061d9e507d833277ada336ab</sha512>
<size>68</size>
<crc32>1750191932</crc32>
<filename>eicar.com</filename>
<filenameWithinInstaller>eicar.com
</filenameWithinInstaller>
</file>
</objects>
<relationships>
<relationship type="createdBy" id="1">
<source>
<ref>file[@id="6ce6f415d8475545be5ba114f208b0ff"]</ref>
</source>
<target>
<ref>file[@id="44d88612fea8a8f36de82e1278abb02f"]</ref>
</target>
<timestamp>2013-03-23T15:12:50.744000</timestamp>
</relationship>
</relationships>
</malwareMetaData>
</iodef-sci:RawData>
</iodef-sci:AttackPattern>
</AdditionalData>
</Method>
<Contact role="creator" type="organization">
<ContactName>iodef-sci.example.com</ContactName>
<RegistryHandle registry="arin">iodef-sci.example-com
</RegistryHandle>
<Email>contact@csirt.example.com</Email>
</Contact>
<EventData>
<Flow>
<System category="source">
<Node>
<Address category="ipv4-addr">192.0.2.200</Address>
<Counter type="event">57</Counter>
</Node>
</System>
<System category="target">
<Node>
<Address category="ipv4-net">192.0.2.16/28</Address>
</Node>
<Service ip_protocol="4">
<Port>80</Port>
</Service>
</System>
</Flow>
<Expectation action="block-host" />
<Expectation action="other" />
</EventData>
</Incident>
</IODEF-Document>
An XML schema describing the elements defined in this document is given here.
<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema targetNamespace="urn:ietf:params:xml:ns:iodef-sci-1.0"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:iodef="urn:ietf:params:xml:ns:iodef-1.0"
xmlns:iodef-sci="urn:ietf:params:xml:ns:iodef-sci-1.0"
elementFormDefault="qualified" attributeFormDefault="unqualified">
<xsd:import namespace="urn:ietf:params:xml:ns:iodef-1.0"
schemaLocation="urn:ietf:params:xml:schema:iodef-1.0"/>
<xsd:complexType name="XMLDATA">
<xsd:complexContent>
<xsd:restriction base="iodef:ExtensionType">
<xsd:sequence>
<xsd:any namespace="##any" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:sequence>
<xsd:attribute name="dtype" type="iodef:dtype-type"
use="required" fixed="xml"/>
<xsd:attribute name="ext-dtype" type="xsd:string" use="optional"/>
<xsd:attribute name="meaning" type="xsd:string"/>
<xsd:attribute name="formatid" type="xsd:string"/>
<xsd:attribute name="restriction" type="iodef:restriction-type"/>
</xsd:restriction>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="Scoring">
<xsd:complexType>
<xsd:sequence>
<xsd:choice>
<xsd:element name="ScoreSet" type="iodef-sci:XMLDATA"
minOccurs="0" maxOccurs="unbounded"/>
<xsd:element ref="iodef:Reference" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:choice>
</xsd:sequence>
<xsd:attribute name="SpecID" type="xsd:string" use="required"/>
<xsd:attribute name="ext-SpecID" type="xsd:string"
use="optional"/>
<xsd:attribute name="ContentID" type="xsd:string"
use="optional"/>
</xsd:complexType>
</xsd:element>
<xsd:element name="AttackPattern">
<xsd:complexType>
<xsd:sequence>
<xsd:choice>
<xsd:element name="RawData" type="iodef-sci:XMLDATA"
minOccurs="0" maxOccurs="unbounded"/>
<xsd:element ref="iodef:Reference" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:choice>
<xsd:element ref="iodef-sci:Platform" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:sequence>
<xsd:attribute name="SpecID" type="xsd:string" use="required"/>
<xsd:attribute name="ext-SpecID" type="xsd:string"
use="optional"/>
<xsd:attribute name="ContentID" type="xsd:string"
use="optional"/>
</xsd:complexType>
</xsd:element>
<xsd:element name="Vulnerability">
<xsd:complexType>
<xsd:sequence>
<xsd:choice>
<xsd:element name="RawData" type="iodef-sci:XMLDATA"
minOccurs="0" maxOccurs="unbounded"/>
<xsd:element ref="iodef:Reference" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:choice>
<xsd:element ref="iodef-sci:Platform" minOccurs="0"
maxOccurs="unbounded"/>
<xsd:element ref="iodef-sci:Scoring" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:sequence>
<xsd:attribute name="SpecID" type="xsd:string" use="required"/>
<xsd:attribute name="ext-SpecID" type="xsd:string"
use="optional"/>
<xsd:attribute name="ContentID" type="xsd:string"
use="optional"/>
</xsd:complexType>
</xsd:element>
<xsd:element name="Weakness">
<xsd:complexType>
<xsd:sequence>
<xsd:choice>
<xsd:element name="RawData" type="iodef-sci:XMLDATA"
minOccurs="0" maxOccurs="unbounded"/>
<xsd:element ref="iodef:Reference" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:choice>
<xsd:element ref="iodef-sci:Platform" minOccurs="0"
maxOccurs="unbounded"/>
<xsd:element ref="iodef-sci:Scoring" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:sequence>
<xsd:attribute name="SpecID" type="xsd:string" use="required"/>
<xsd:attribute name="ext-SpecID" type="xsd:string"
use="optional"/>
<xsd:attribute name="ContentID" type="xsd:string"
use="optional"/>
</xsd:complexType>
</xsd:element>
<xsd:element name="Platform">
<xsd:complexType>
<xsd:sequence>
<xsd:choice>
<xsd:element name="RawData" type="iodef-sci:XMLDATA"
minOccurs="0" maxOccurs="unbounded"/>
<xsd:element ref="iodef:Reference" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:choice>
</xsd:sequence>
<xsd:attribute name="SpecID" type="xsd:string" use="required"/>
<xsd:attribute name="ext-SpecID" type="xsd:string"
use="optional"/>
<xsd:attribute name="ContentID" type="xsd:string"
use="optional"/>
</xsd:complexType>
</xsd:element>
<xsd:element name="EventReport">
<xsd:complexType>
<xsd:sequence>
<xsd:choice>
<xsd:element name="RawData" type="iodef-sci:XMLDATA"
minOccurs="0" maxOccurs="unbounded"/>
<xsd:element ref="iodef:Reference" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:choice>
</xsd:sequence>
<xsd:attribute name="SpecID" type="xsd:string" use="required"/>
<xsd:attribute name="ext-SpecID" type="xsd:string"
use="optional"/>
<xsd:attribute name="ContentID" type="xsd:string"
use="optional"/>
</xsd:complexType>
</xsd:element>
<xsd:element name="Verification">
<xsd:complexType>
<xsd:sequence>
<xsd:choice>
<xsd:element name="RawData" type="iodef-sci:XMLDATA"
minOccurs="0" maxOccurs="unbounded"/>
<xsd:element ref="iodef:Reference" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:choice>
</xsd:sequence>
<xsd:attribute name="SpecID" type="xsd:string" use="required"/>
<xsd:attribute name="ext-SpecID" type="xsd:string"
use="optional"/>
<xsd:attribute name="ContentID" type="xsd:string"
use="optional"/>
</xsd:complexType>
</xsd:element>
<xsd:element name="Remediation">
<xsd:complexType>
<xsd:sequence>
<xsd:choice>
<xsd:element name="RawData" type="iodef-sci:XMLDATA"
minOccurs="0" maxOccurs="unbounded"/>
<xsd:element ref="iodef:Reference" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:choice>
</xsd:sequence>
<xsd:attribute name="SpecID" type="xsd:string" use="required"/>
<xsd:attribute name="ext-SpecID" type="xsd:string"
use="optional"/>
<xsd:attribute name="ContentID" type="xsd:string"
use="optional"/>
</xsd:complexType>
</xsd:element>
</xsd:schema>
This document specifies a format for encoding a particular class of security incidents appropriate for exchange across organizations. As merely a data representation, it does not directly introduce security issues. However, it is guaranteed that parties exchanging instances of this specification will have certain concerns. For this reason, the underlying message format and transport protocol used MUST ensure the appropriate degree of confidentiality, integrity, and authenticity for the specific environment. Specific security considerations are detailed in the messaging and transport documents, where the exchange of formatted information is automated. See Real-time Inter-network Defense (RID) [RFC6545] Section 9 for a detailed overview of security requirements and considerations.
It is RECOMMENDED that organizations who exchange data using this document develop operating procedures that minimally consider the following areas of concern.
The underlying messaging format, IODEF, provides data markers to indicate the sensitivity level of specific classes within the structure as well as for the entire XML document. The "restriction" attribute accomplishes this with four attribute values in IODEF. These values are RECOMMENDED for use at the application level, prior to transport, to protect data as appropriate. A standard mechanism to apply XML encryption using these attribute values as triggers is defined in RID [RFC6545] Section 9.1. This mechanism may be used whether or not the RID and RID Transport binding [RFC6546] are used in the exchange to provide object level security on the data to prevent possible intermediary systems or middle-boxes from having access to the data being exchanged. In areas where transmission security or secrecy is questionable, the application of a XML digital signature [xmldsig] and/or encryption on each report will counteract both of these concerns. The data markers are RECOMMENDED for use by applications for managing access controls, however access controls and management of those controls are out-of-scope for this document. Options such as the usage of a standard language (e.g. XACML [XACML]) for the expression of authorization policies can be used to enable source and destination systems to better coordinate and align their respective policy expressions.
Any transport protocol used to exchange instances of IODEF documents MUST provide appropriate guarantees of confidentiality, integrity, and authenticity. The use of a standardized security protocol is encouraged. The RID protocol [RFC6545] and its associated transport binding [RFC6546] provide such security with options for mutual authentication session encryption and include application levels concerns such as policy and work flow.
The critical security concerns are that these structured information may be falsified, accessed by unintended entities, or they may become corrupt during transit. We expect that each exchanging organization will determine the need, and mechanism, for transport protection.
For a complete review of privacy considerations when transporting incident related information, please see RID [RFC6545] Section 9.5. Whether or not the RID protocol is used, the privacy considerations are important to consider as incident information is often sensitive and may contain privacy related information about individuals/organizations or endpoints involved. Often times, organizations will require legal review and formal polices to be established which outline specific details of what information can be exchanged with specific entities. Typically, identifying information is anonymized where possible and appropriate. In some cases, information brokers are used to further anonymize the source of exchanged information so that other entities are unaware of the origin of a detected threat, whether or not that threat was realized.
It is RECOMMENDED that policies and procedures for the exchange of cybersecurity information are established prior to participation in data exchanges. Policy and workflow procedures for the exchange of cybersecurity information often require executive level approvals and legal reviews to appropriately establish limits on what information can be exchanged with specific organizations. RID [RFC6545] Section 9.6 outlines options and considerations for application developers to consider for the policy and workflow design.
The Cybersecurity Information extension is merely a data format. Applications and transport protocols that store or exchange IODEF documents using information that can be represented through this extension will be a target for attacks. It is RECOMMENDED that systems and applications storing or exchanging this information are properly secured, have minimal services enabled, maintain access controls and monitoring procedures.
This document uses URNs to describe XML namespaces and XML schemata [XMLschemaPart1] [XMLschemaPart2] conforming to a registry mechanism described in [RFC3688].
Registration request for the IODEF structured cybersecurity information extension namespace:
Registration request for the IODEF structured cybersecurity information extension XML schema:
This memo creates the following registry for IANA to manage:
The Designated Expert is expected to consult with the mile (Managed Incident Lightweight Exchange) working group or its successor if any such WG exists (e.g., via email to the working group's mailing list). The Designated Expert is expected to retrieve the SCI specification from the provided URI in order to check the public availability of the specification and verify the correctness of the URI. An important responsibility of the Designated Expert is to ensure that the registered Applicable Classes are appropriate for the registered SCI specification.
We would like to acknowledge David Black from EMC, who kindly provided generous support, especially on the IANA registry issues. We also would like to thank Jon Baker from MITRE, Eric Burger from Georgetown University, Paul Cichonski from NIST, Panos Kampanakis from CISCO, Pearl Liang from IANA, Ivan Kirillov from MITRE, Robert Martin from MITRE, Alexey Melnikov from Isode, Kathleen Moriarty from EMC, Lagadec Philippe from NATO, Sean Turner from IECA Inc., Shuhei Yamaguchi from NICT, Anthony Rutkowski from Yaana Technology, Brian Trammell from ETH Zurich, David Waltermire from NIST, and James Wendorf from IEEE, for their sincere discussion and feedback on this document.