Security Automation and Continuous Monitoring M. Cokus
Internet-Draft D. Haynes
Intended status: Informational D. Rothenberg
Expires: September 8, 2016 The MITRE Corporation
J. Gonzalez
Department of Homeland Security
March 7, 2016
OVAL(R) Directives Model
draft-rothenberg-sacm-oval-directives-model-00
Abstract
This document specifies Version 5.11.1 of the OVAL Directives Model
which defines the constructs used to tailor the level of detail
contained within a set of OVAL Results.
Status of This Memo
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This Internet-Draft will expire on September 8, 2016.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. OVAL Directives Model . . . . . . . . . . . . . . . . . . . . 3
3. OVAL Directives Model Schema . . . . . . . . . . . . . . . . 4
4. Intellectual Property Considerations . . . . . . . . . . . . 8
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
The Open Vulnerability and Assessment Language (OVAL) [OVAL-WEBSITE]
is an international, information security community effort to
standardize how to assess and report upon the machine state of
systems. For over ten years, OVAL has been developed in
collaboration with any and all interested parties to promote open and
publicly available security content and to standardize the
representation of this information across the entire spectrum of
security tools and services.
OVAL provides an established framework for making assertions about a
system's state by standardizing the three main steps of the
assessment process: representing the current machine state; analyzing
the system for the presence of the specified machine state; and
representing the results of the assessment which facilitates
collaboration and information sharing among the information security
community and interoperability among tools.
This draft is the part of the OVAL contribution to the IETF SACM WG
that standardizes the representation of the results of an assessment.
It is intended to serve as a starting point for the endpoint posture
assessment data modeling needs of SACM specifically a capability to
specify the level of detail in Evaluation Results.
1.1. Requirements Language
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].
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2. OVAL Directives Model
The OVAL Directives Model is used to control what result information
is included in the OVAL Results as well as specify its level of
detail.
+---------------+---------------------------+-------+---------------+
| Property | Type | Count | Description |
+---------------+---------------------------+-------+---------------+
| generator | oval:GeneratorType | 1 | Information |
| | | | regarding the |
| | | | generation of |
| | | | the OVAL |
| | | | Directives |
| | | | content. The |
| | | | timestamp |
| | | | property of |
| | | | the generator |
| | | | MUST |
| | | | represent the |
| | | | time at which |
| | | | the oval_dire |
| | | | ctives was |
| | | | created. |
| | | | |
| directives | oval- | 1 | Describes the |
| | res:DefaultDirectivesType | | default set |
| | | | of directives |
| | | | that specify |
| | | | the results |
| | | | that have |
| | | | been included |
| | | | in the OVAL |
| | | | Results. |
| | | | |
| class_directi | oval- | 0..5 | Describes the |
| ves | res:ClassDirectivesType | | set of |
| | | | directives |
| | | | that specify |
| | | | the class- |
| | | | specific |
| | | | results that |
| | | | have been |
| | | | included in |
| | | | the OVAL |
| | | | Results. |
| | | | |
| signature | ext:Signature | 0..1 | Mechanism to |
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| | | | ensure the |
| | | | integrity and |
| | | | authenticity |
| | | | of the OVAL |
| | | | Directives |
| | | | content. |
+---------------+---------------------------+-------+---------------+
Table 1: oval_directives Construct
3. OVAL Directives Model Schema
The XML Schema that implements this OVAL Directives Model can be
found below.
The following is a
description of the elements, types,
and attributes that compose the
core schema for encoding Open
Vulnerability and Assessment
Language (OVAL) Directives. Each of
the elements, types, and attributes
that make up the Core Directives
Schema are described in detail and
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should provide the information
necessary to understand what each
object represents. This document is
intended for developers and assumes
some familiarity with XML. A high
level description of the
interaction between these objects
is not outlined
here.
Core Directives
5.11.1
4/22/2015 09:00:00 AM
Copyright (C) 2010 United States
Government. All Rights Reserved.
The
oval_directives element is the
root of an OVAL Directive
Document. Its purpose is to
bind together the generator
and the set of directives
contained in the document. The
generator section must be
present and provides
information about when the
directives document was
compiled and under what
version. The optional
Signature element allows an
XML Signature as defined by
the W3C to be attached to the
document. This allows
authentication and data
integrity to be provided to
the user. Enveloped signatures
are supported. More
information about the official
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W3C Recommendation regarding
XML digital signatures can be
found at
http://www.w3.org/TR/xmldsig-core/.
The
required generator
section provides
information about when
the directives document
was compiled and under
what
version.
The
required directives
section presents flags
describing what
information must be been
included in an oval
results document. This
element represents the
default set of
directives. These
directives apply to all
classes of definitions
for which there is not a
class specific set of
directives.
The
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optional class_directives
section presents flags
describing what
information has been
included in the results
document for a specific
OVAL Definition class.
The directives for a
particlar class override
the default
directives.
The
optional Signature
element allows an XML
Signature as defined by
the W3C to be attached to
the document. This allows
authentication and data
integrity to be provided
to the user. Enveloped
signatures are supported.
More information about
the official W3C
Recommendation regarding
XML digital signatures
can be found at
http://www.w3.org/TR/xmldsig-core/.
The class
attribute on
class_directives must be
unique.
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4. Intellectual Property Considerations
Copyright (C) 2010 United States Government. All Rights Reserved.
DHS, on behalf of the United States, owns the registered OVAL
trademarks, identifying the OVAL STANDARDS SUITE and any component
part, as that suite has been provided to the IETF Trust. A "(R)"
will be used in conjunction with the first use of any OVAL trademark
in any document or publication in recognition of DHS's trademark
ownership.
5. Acknowledgements
The authors wish to thank DHS for sponsoring the OVAL effort over the
years which has made this work possible. The authors also wish to
thank the original authors of this document Jonathan Baker, Matthew
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Hansbury, and Daniel Haynes of the MITRE Corporation as well as the
OVAL Community for its assistance in contributing and reviewing the
original document. The authors would also like to acknowledge Dave
Waltermire of NIST for his contribution to the development of the
original document.
6. IANA Considerations
This memo includes no request to IANA.
7. Security Considerations
While OVAL is just a set of data models and does not directly
introduce security concerns, it does provide a mechanism by which to
represent endpoint posture assessment information. This information
could be extremely valuable to an attacker allowing them to learn
about very sensitive information including, but, not limited to:
security policies, systems on the network, criticality of systems,
software and hardware inventory, patch levels, user accounts and much
more. To address this concern, all endpoint posture assessment
information should be protected while in transit and at rest.
Furthermore, it should only be shared with parties that are
authorized to receive it.
Another possible security concern is due to the fact that content
expressed as OVAL has the ability to impact how a security tool
operates. For example, content may instruct a tool to collect
certain information off a system or may be used to drive follow-up
actions like remediation. As a result, it is important for security
tools to ensure that they are obtaining OVAL content from a trusted
source, that it has not been modified in transit, and that proper
validation is performed in order to ensure it does not contain
malicious data.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
.
8.2. Informative References
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[OVAL-WEBSITE]
The MITRE Corporation, "The Open Vulnerability and
Assessment Language", 2015,
.
Authors' Addresses
Michael Cokus
The MITRE Corporation
903 Enterprise Parkway, Suite 200
Hampton, VA 23666
USA
Email: msc@mitre.org
Daniel Haynes
The MITRE Corporation
202 Burlington Road
Bedford, MA 01730
USA
Email: dhaynes@mitre.org
David Rothenberg
The MITRE Corporation
202 Burlington Road
Bedford, MA 01730
USA
Email: drothenberg@mitre.org
Juan Gonzalez
Department of Homeland Security
245 Murray Lane
Washington, DC 20548
USA
Email: juan.gonzalez@dhs.gov
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