Internet DRAFT - draft-wandw-sacm-information-model
draft-wandw-sacm-information-model
Internet Engineering Task Force D. Waltermire, Ed.
Internet-Draft NIST
Intended status: Informational K. Watson
Expires: January 4, 2015 DHS
July 3, 2014
Information Model for Endpoint Assessment
draft-wandw-sacm-information-model-00
Abstract
This document proposes a draft information model for endpoint posture
assessment. It describes the information needed to perform certain
assessment activities.
Status of This Memo
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This Internet-Draft will expire on January 4, 2015.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Problem Scope . . . . . . . . . . . . . . . . . . . . . . 5
2.2. Mapping to SACM Use Cases . . . . . . . . . . . . . . . . 6
3. Conventions used in this document . . . . . . . . . . . . . . 7
3.1. Requirements Language . . . . . . . . . . . . . . . . . . 7
4. Terms and Definitions . . . . . . . . . . . . . . . . . . . . 7
4.1. Pre-defined and Modified Terms . . . . . . . . . . . . . 7
4.2. New Terms . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Foundational Concepts . . . . . . . . . . . . . . . . . . . . 8
5.1. Core Principles . . . . . . . . . . . . . . . . . . . . . 8
5.2. Architecture Assumptions . . . . . . . . . . . . . . . . 9
6. Endpoint Management . . . . . . . . . . . . . . . . . . . . . 13
6.1. Core Information Need . . . . . . . . . . . . . . . . . . 13
6.2. Process Area Description . . . . . . . . . . . . . . . . 13
6.3. Endpoint Management Process Operations . . . . . . . . . 14
6.4. Information Model Requirements . . . . . . . . . . . . . 14
6.4.1. Enroll Operation . . . . . . . . . . . . . . . . . . 14
7. Software Management . . . . . . . . . . . . . . . . . . . . . 15
7.1. Core Information Needs . . . . . . . . . . . . . . . . . 15
7.2. Process Area Description . . . . . . . . . . . . . . . . 16
7.3. Software Management Process Operations . . . . . . . . . 18
7.4. Information Model Requirements . . . . . . . . . . . . . 18
7.4.1. Define Guidance . . . . . . . . . . . . . . . . . . . 19
7.4.2. Collect Inventory . . . . . . . . . . . . . . . . . . 19
7.4.3. Evaluate Software Inventory Posture . . . . . . . . . 20
7.4.4. Report Evaluation Results . . . . . . . . . . . . . . 21
8. Configuration Management . . . . . . . . . . . . . . . . . . 21
8.1. Core Information Needs . . . . . . . . . . . . . . . . . 22
8.2. Process Area Description . . . . . . . . . . . . . . . . 22
8.2.1. The Existence of Configuration Item Guidance . . . . 23
8.2.2. Configuration Collection Guidance . . . . . . . . . . 24
8.2.3. Configuration Evaluation Guidance . . . . . . . . . . 24
8.2.4. Local Configuration Management Process . . . . . . . 24
8.3. Configuration Management Operations . . . . . . . . . . . 26
8.4. Information Model Requirements . . . . . . . . . . . . . 26
8.4.1. Define Guidance . . . . . . . . . . . . . . . . . . . 26
8.4.2. Collect Posture Attributes Operation . . . . . . . . 28
8.4.3. Evaluate Posture Attributes Operation . . . . . . . . 29
8.4.4. Report Evaluation Results Operation . . . . . . . . . 30
9. Vulnerability Management . . . . . . . . . . . . . . . . . . 31
9.1. Core Information Needs . . . . . . . . . . . . . . . . . 31
9.2. Process Area Description . . . . . . . . . . . . . . . . 31
9.3. Vulnerability Management Process Operations . . . . . . . 32
9.4. Information Model Requirements . . . . . . . . . . . . . 32
9.4.1. Collect Vulnerability Reports . . . . . . . . . . . . 32
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9.4.2. Evaluate Vulnerability Posture . . . . . . . . . . . 33
9.4.3. Report Evaluation Results . . . . . . . . . . . . . . 35
10. From Information Needs to Information Elements . . . . . . . 35
11. Information Model Elements . . . . . . . . . . . . . . . . . 36
11.1. Asset Identifiers . . . . . . . . . . . . . . . . . . . 37
11.1.2. Endpoint Identification . . . . . . . . . . . . . . 40
11.1.3. Software Identification . . . . . . . . . . . . . . 41
11.1.4. Hardware Identification . . . . . . . . . . . . . . 44
11.2. Other Identifiers . . . . . . . . . . . . . . . . . . . 44
11.2.1. Platform Configuration Item Identifier . . . . . . . 44
11.2.2. Configuration Item Identifier . . . . . . . . . . . 50
11.2.3. Vulnerability Identifier . . . . . . . . . . . . . . 52
11.3. Endpoint characterization . . . . . . . . . . . . . . . 52
11.4. Posture Attribute Expression . . . . . . . . . . . . . . 56
11.4.2. Platform Configuration Attributes . . . . . . . . . 56
11.5. Actual Value Representation . . . . . . . . . . . . . . 58
11.5.1. Software Inventory . . . . . . . . . . . . . . . . . 58
11.5.2. Collected Platform Configuration Posture Attributes 59
11.6. Evaluation Guidance . . . . . . . . . . . . . . . . . . 60
11.6.1. Configuration Evaluation Guidance . . . . . . . . . 60
11.7. Evaluation Result Reporting . . . . . . . . . . . . . . 62
11.7.1. Configuration Evaluation Results . . . . . . . . . . 62
11.7.2. Software Inventory Evaluation Results . . . . . . . 64
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 64
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 65
14. Security Considerations . . . . . . . . . . . . . . . . . . . 65
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 65
15.1. Normative References . . . . . . . . . . . . . . . . . . 65
15.2. Informative References . . . . . . . . . . . . . . . . . 65
15.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 69
1. Introduction
The posture of an endpoint is the status of an endpoint's assets with
respect to the security policies and risk models of the organization.
A system administrator needs to be able to determine which of the
collection of assets that constitute an endpoint have a security
problem and which do not conform the organization's security
policies. The CIO needs to be able to determine whether endpoints
have security postures that conform to the organization's policies to
ensure that the organization is complying with its fiduciary and
regulatory responsibilities. The regulator or auditor needs to be
able to assess the level of due diligence being achieved by an
organization to ensure that all regulations and due diligence
expectations are being met. The operator needs to understand which
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assets have deviated from organizational policies so that those
assets can be remedied.
Operators will focus on which endpoints are composed of specific
assets with problems. CIO and auditors need a characterization of
how an organization is performing as a whole to manage the posture of
its endpoints. All of these actors need deployed capabilities that
implement security automation standards in the form of data formats,
interfaces, and protocols to be able to assess, in a timely and
secure fashion, all assets on all endpoints within their enterprise.
This information model provides a basis to identify the desirable
characteristics of data models to support these scenarios. Other
SACM specifications, such as the SACM Architecture, will describe the
potential components of an interoperable system solution based on the
SACM information model to address the requirements for scalability,
timeliness, and security.
This draft was developed in response to the Call for Contributions
for the SACM Information Model sent to NIST
[IM-LIAISON-STATEMENT-NIST]. This draft proposes a notional
information model for endpoint posture assessment. It describes the
information needed to perform certain assessment activities and
relevant work that may be used as a basis for the development of
specific data models. The terms information model and data model
loosely align with the terms defined in RFC3444 [RFC3444].
The four primary activities to support this information model are:
1. Endpoint Identification
2. Endpoint Characterization
3. Endpoint Attribute Expression/Representation
4. Policy evaluation expression and results reporting
These activities are aimed at the level of the technology that
performs operations to support collection, evaluation, and reporting.
Review of the SACM Use Case [I-D.ietf-sacm-use-cases] usage scenarios
show a common set of business process areas that are critical to
understanding endpoint posture such that appropriate policies,
security capabilities, and decisions can be developed and
implemented.
For this information model we have chosen to focus on the following
business process areas:
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o Endpoint Management
o Software Management
o Configuration Management
o Vulnerability Management
These management process areas are a way to connect the SACM use
cases and building blocks [I-D.ietf-sacm-use-cases] to the
organizational needs such that the definition of information
requirements has a clearly understood context.
2. Problem Statement
Scalable and sustainable collection, expression, and evaluation of
endpoint information is foundational to SACM's objectives. To secure
and defend one's network one must reliably determine what devices are
on the network, how those devices are configured from a hardware
perspective, what software products are installed on those devices,
and how those products are configured. We need to be able to
determine, share, and use this information in a secure, timely,
consistent, and automated manner to perform endpoint posture
assessments.
This represents a large and broad set of mission and business
processes, and to make the most effective of use of technology, the
same data must support multiple processes. The activities and
processes described within this memo tend to build off of each other
to enable more complex characterization and assessment. In an effort
to create an information model that serves a common set of management
processes represented by the usage scenarios in the SACM Use Cases
document, we have narrowed down the scope of this model.
2.1. Problem Scope
The goal of this first iteration of the information model is to
define the information needs for an organization to effectively
manage the endpoints operating on their network, the software
installed on those endpoints, and the configuration of that software.
Once we have those three business processes in place, we can then
identify vulnerable endpoints in a very efficient manner.
The four business process areas represent a large set of tasks that
support endpoint posture assessment. In an effort to address the
most basic and foundational needs, we have also narrowed down the
scope inside of each of the business processes to a set of defined
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tasks that strive to achieve specific results in the operational
environment and the organization. These tasks are:
1. Define the assets. This is what we want to know about an asset.
For instance, organizations will want to know what software is
installed and its many critical security attributes such as patch
level.
2. Resolve what assets actually compose an endpoint. This requires
populating the data elements and attributes needed to exchange
information pertaining to the assets composing an endpoint.
3. Express what expected values for the data elements and attributes
need to be evaluated against the actual collected instances of
asset data. This is how an organization can express its policy
for an acceptable data element or attribute value. A system
administrator can also identify specific data elements and
attributes that represent problems, such as vulnerabilities, that
need to be detected on an endpoint.
4. Evaluate the collected instances of the asset data against those
expressed in the policy.
5. Report the results of the evaluation.
2.2. Mapping to SACM Use Cases
This information model directly corresponds to all four use cases
defined in the SACM Use Cases draft [I-D.ietf-sacm-use-cases]. It
uses these use cases in coordination to achieve a small set of well-
defined tasks.
Sections 6 thru 9 address each of the process areas. For each
process area, a "Process Area Description" sub-section represent an
end state that is consistent with all the General Requirements and
many of the Use Case Requirements identified in the requirements
draft [I-D.camwinget-sacm-requirements].
The management process areas and supporting operations defined in
this memo directly support REQ004 Endpoint Discovery; REQ005-006
Attribute and Information Based Queries, and REQ0007 Asynchronous
Publication.
In addition, the operations that defined for each business process in
this memo directly correlate with the typical workflow identified in
the SACM Use Case document.
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3. Conventions used in this document
3.1. 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].
4. Terms and Definitions
This section describes terms that have been defined by other RFCs and
Internet Drafts, as well as new terms introduced in this document.
4.1. Pre-defined and Modified Terms
This section contains pre-defined terms that are sourced from other
IETF RFCs and Internet Drafts. Descriptions of terms in this section
will reference the original source of the term and will provide
additional specific context for the use of each term in SACM. For
sake of brevity, terms from [I-D.ietf-sacm-terminology] are not
repeated here unless the original meaning has been changed in this
document.
Asset For this Information Model it is necessary to change the
scope of the definition of asset from the one provided in
[I-D.ietf-sacm-terminology]. Originally defined in [RFC4949]
and referenced in [I-D.ietf-sacm-terminology] as "a system
resource that is (a) required to be protected by an
information system's security policy, (b) intended to be
protected by a countermeasure, or (c) required for a system's
mission." This definition generally relates to an "IT
Asset", which in the context of this document is overly
limiting. For use in this document, a broader definition of
the term is needed to represent non-IT asset types as well.
In [NISTIR-7693] an asset is defined as "anything that has
value to an organization, including, but not limited to,
another organization, person, computing device, information
technology (IT) system, IT network, IT circuit, software
(both an installed instance and a physical instance), virtual
computing platform (common in cloud and virtualized
computing), and related hardware (e.g., locks, cabinets,
keyboards)." This definition aligns better with common
dictionary definitions of the term and better fits the needs
of this document.
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4.2. New Terms
IT Asset Originally defined in [RFC4949] as "a system resource that
is (a) required to be protected by an information system's
security policy, (b) intended to be protected by a
countermeasure, or (c) required for a system's mission."
Security Content Automation Protocol (SCAP) According to SP800-126,
SCAP, pronounced "ess-cap", is "a suite of specifications
that standardize the format and nomenclature by which
software flaw and security configuration information is
communicated, both to machines and humans." SP800-117
revision 1 [SP800-117] provides a general overview of SCAP
1.2. The 11 specifications that comprise SCAP 1.2 are
synthesized by a master specification, SP800-126 revision 2
[SP800-126], that addresses integration of the specifications
into a coherent whole. The use of "protocol" in its name is
a misnomer, as SCAP defines only data models. SCAP has been
adopted by a number of operating system and security tool
vendors.
5. Foundational Concepts
5.1. Core Principles
This information model is built on the following core principles:
o Collection and Evaluation are separate tasks.
o Collection and Evaluation can be performed on the endpoint, at a
local server that communicates directly with the endpoint, or
based on data queried from a back end data store that does not
communicate directly with any endpoints.
o Every entity (human or machine) that notifies, queries, or
responds to any guidance, collection, or evaluation task must have
a way of identifying itself and/or presenting credentials.
Authentication is a key step in all of the processes, and while
needed to support the business processes, information needs to
support authentication are not highlighted in this information
model. There is already a large amount of existing work that
defines information needs for authentication.
o Policies are reflected in guidance for collection, evaluation, and
reporting.
o Guidance will often be generated by humans or through the use of
transformations on existing automation data. Is some cases,
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guidance will be generated dynamically based on shared information
or current operational needs. As guidance is created it will be
published to an appropriate guidance data store allowing guidance
to be managed in and retrieved from convenient locations.
o Operators of a continuous monitoring or security automation system
will need to make decisions when defining policies about what
guidance to use or reference. The guidance used may be directly
associated with policy or may be queried dynamically based on
associated metadata.
o Guidance can be gathered from multiple data stores. It may be
retrieved at the point of use or may be packaged and forwarded for
later use. Guidance may be retrieved in event of a collection or
evaluation trigger or it may be gathered ahead of time and stored
locally for use/reference during collection and evaluation
activities.
5.2. Architecture Assumptions
This information model will focus on WHAT information needs to be
exchanged to support the business process areas. The architecture
document is the best place to represent the HOW and the WHERE this
information is used. In an effort to ensure that the data models
derived from this information model scale to the architecture, four
core architectural components need to be defined. They are
producers, consumers, capabilities, and repositories. These elements
are defined as follows:
o Producers (e.g., Evaluation Producer) collect, aggregate, and/or
derive information items and provide them to consumers. For this
model there are Collection, Evaluation, and Results Producers.
There may or may not be Guidance Producers.
o Consumers (e.g., Collection Consumer) request and/or receive
information items from producers for their own use. For this
model there are Collection, Evaluation, and Results Consumers.
There may or may not be Guidance Consumers.
o Capabilities (e.g., Posture Evaluation Capability) take the input
from one or more producers and perform some function on or with
that information. For this model there are Collection Guidance,
Collection, Evaluation Guidance, Evaluation, Reporting Guidance,
and Results Reporting Capabilities.
o Repositories (e.g., Enterprise Repository) store information items
that are input to or output from Capabilities, Producers, and
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Consumers. For this model we refer to generic Enterprise and
Guidance Repositories.
Information that needs to be communicated by or made available to any
of these components will be specified in each of the business process
areas.
In the most trivial example, illustrated in Figure 1, Consumers
either request information from, or are notified by, Producers.
+----------+ Request +----------+
| <-----------------+ |
| Producer | | Consumer |
| +-----------------> |
+----------+ Response +----------+
+----------+ +----------+
| | Notify | |
| Producer +-----------------> Consumer |
| | | |
+----------+ +----------+
Figure 1: Example Producer/Consumer Interactions
As illustrated in Figure 2, writing and querying from data
repositories are a way in which this interaction can occur in an
asynchronous fashion.
+----------+ +----------+
| | | |
| Producer | | Consumer |
| | | |
+-----+----+ +----^-----+
| |
Write | +------------+ | Query
| | | |
+-----> Repository +-------+
| |
+------------+
Figure 2: Producer/Consumer Repository Interaction
To perform an assessment, these elements are chained together. The
diagram below is illustrative of this and process, and is meant to
demonstrate WHAT basic information exchanges need to occur, while
trying to maintain flexibility in HOW and WHERE they occur.
For example:
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o the collection capability can reside on the endpoint or not.
o the collection producer can be part of the collection capability
or not.
o a repository can be directly associated with a producer and/or an
evaluator or stand on its own.
o there can be multiple "levels" of producers and consumers.
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+-------------+
|Evaluation |
+-------------+ |Guidance +--+
|Endpoint | |Capability | |
+-------+ | +-------------+ |
| | | |
| +-------+-----+ +-----v-------+
| Collection | |Evaluation |
+-> Capability +--+--------+ |Capability |
| | |Collection | +-----------+ +----------+
| +------------+Producer | | |---| |
| | | |Collection | |Evaluation|
| | | |Consumer | |Producer |
| +----+------+ +----^------+ +---+------+
++---------+ | | |
|Collection| +-----v------+ +---+--------+ |
|Guidance | | | |Collection | |
|Capability| |Collection | |Producer | |
| | |Consumer |-----| | |
+----------+ +------------+ +------------+ |
| Collection | |
| Repository | |
+------------+ |
|
+--------------+ +---------------+ |
|Evaluation | |Evaluation | |
|Results | |Consumer <-----+
|Producer |-----------| |
+-----+--------+ +---------------+
| |Results Reporting|
| |Capability |
| +------------^----+
| |
+-----v--------+ +----+------+
|Evaluation | |Reporting |
|Results | |Guidance |
|Consumer | |Repository |
+---+----------+ +-----------+ +-------------+
| | Results |
+-----------------------------> Repository |
| |
+-------------+
Figure 3: Producer/Consumer Complex Example
This illustrative example in Figure 3 provides a set of information
exchanges that need to occur to perform a posture assessment. The
rest of this information model is using this set of exchanges based
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on these core architectural components as the basis for determining
information elements.
6. Endpoint Management
6.1. Core Information Need
Unique Endpoint Identifier: The organization needs to uniquely
identify and label an endpoint, regardless of if it is known
about a priori or discovered it in the operational
environment.
6.2. Process Area Description
The authors envisage a common "lifecycle" for all endpoints in an
enterprise network. Each endpoint's lifecycle begins with an
"enrollment" operation, where a description of the endpoint is added
to the enterprise repository of "known endpoints." The enrollment
operation may be performed manually, in advance of an endpoint's
first connection request, or automatically at the time of an
endpoint's first connection request.
Manual enrollment is typically done in situations where endpoint
devices are issued by the enterprise (as contrasted with "bring your
own device" situations), and must first be configured by the
enterprise's Information Technology (IT) department before they are
allowed to connect to the network. When enrollment is performed in
this manner, administrators typically know a lot about the physical
endpoint, such as any persistent identifying characteristics (e.g.,
its primary MAC address), its assigned IP address and planned
physical location within the network, its role within the network
(e.g., end-user workstation, database server, webserver, etc.), and
the responsible parties (e.g., asset owner, device maintainer).
These data elements may be associated with the endpoint when the
endpoint characteristics are entered into an enterprise repository as
part of the enrollment process.
For networks with fewer access restrictions (e.g., guest wireless
networks, and "bring your own device" networks), enrollment may occur
automatically when an endpoint device first attempts to connect to
the network. In these situations, enrollment typically happens at
machine speed, without a human administrator in the loop. As a
result, much less may be known about the endpoint that is being
enrolled, and thus only minimal data elements may be available for
automatic entry into an enterprise repository.
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6.3. Endpoint Management Process Operations
Waltermire et al. define an endpoint as "any physical or virtual
device that may have a network address" (Waltermire, et al., 2014).
Endpoint management encompasses all security automation processes
involved in the tracking and monitoring of endpoints as devices which
are connected (even if only transiently) to an enterprise network.
Based on the vision, we have identified the following operations for
Endpoint Management:
1. Enroll/Expel: Add an endpoint to (or remove an endpoint from) the
list of known endpoints that may be allowed to access network
resources.
6.4. Information Model Requirements
In this section we describe the data that enterprises will need to
carry out for each endpoint management operation.
6.4.1. Enroll Operation
We allow for two modes of the "Enroll" operation: (1) manual, and (2)
automatic. When the "enroll" operation is performed in the "manual"
mode, enrollment occurs before the enrolled endpoint first attempts
to connect to the enterprise network. The result of manual
enrollment is that the enterprise repository is updated with records
to indicate that the endpoint is enrolled and thus is "known".
During enrollment, credentials may be issued (e.g., host or user
certificates) and placed on the endpoint, to be furnished each time
the endpoint attempts to connect to the network. We assume that as a
byproduct of manual enrollment, the enterprise repository will
contain a persistent unique identifier for the enrolled endpoint.
In the automatic mode, enrollment occurs as a side effect of a
connection request. Here, the endpoint requesting access has not
previously been manually enrolled and is thus "unknown". If policy
permits, unknown endpoints may still be allowed to connect to the
network and may be given limited access to resources.
To complete the enrollment operation, the following information
elements may be needed ('M' indicates 'mandatory' and 'O' indicates
'optional'):
o (M) Unique Endpoint Identifier: a persistent unique identifier for
the endpoint
o (O) Device Role: the organization needs to identify the intended
use of the device (e.g., workstation, server, router).
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o (O) Asset Ownership: the organization needs to know what person
and/or organization is responsible for maintaining the device.
o (O) Other Identifying Characteristics: the organization must know
what other identifiers can be mapped to the Unique Endpoint
Identifier (e.g., IP address, MAC address).
While many of these elements may be automatically collected, data
pertaining to device role and ownership often require manual entry.
7. Software Management
This section presents an information model for managing information
about software installed on endpoints. Software management
encompasses the subset of tasks within security automation and
continuous monitoring which play a role in compiling inventories of
software products installed on endpoints and transmitting those
inventories to software inventory data consumers. Software inventory
data consumers may store the software inventory data and/or perform
enterprise-level software inventory-related security posture
assessments. While software enforcement policies that are invoked
and enforced at the time of installation or execution are out of the
scope of SACM, they require the same software guidance information to
be produced and exchanged. For that reason, the first operation is
to Define Guidance making it available to perform a posture
evaluation activity during any operation.
7.1. Core Information Needs
Unique Endpoint Identifier: Organizations need to be able to relate
the instances of software to the endpoint on which it is
installed. This should be consistent with the identification
of the endpoint when it is enrolled (see Section 6.4.1).
Unique Software Identifier: Organizations need to be able to
uniquely identify and label software installed on an
endpoint. Specifically, they need to know the name,
publisher, unique ID, and version; and any related patches.
In some cases the software's identity might be known a priori
by the organization; in other cases, a software identity
might be first detected by an organization when the software
is first inventoried in an operational environment. Due to
this, it is important that an organization have a stable and
consistent means to identify software found during
collection.
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7.2. Process Area Description
The authors envisage an automated capability that will collect
software inventory data on endpoints and transmit that data to
interested software inventory data consumers. "Inventory data" is
information about software products that may be operating systems,
end-user applications, or other software-based systems and services-
that have been added to, removed from, or modified on endpoints. The
collection and transmission of inventory data from a given endpoint
to an inventory data consumer may be scheduled, event-driven, or on
demand based on the requested collection policy. That is, endpoints
may be configured to collect and transmit inventory data on a
predefined schedule (scheduled), in response to a change in inventory
state (event-driven), or whenever an inventory consumer requests (on
demand).
On any occasion when inventory data is collected and transmitted, the
data may be "complete" or be an "update" to previously-transmitted
data based on the requested collection policy. Inventory data is
considered to be "complete" when it is intended to reflect a
comprehensive and up-to-date enumeration of all software products
that are believed to be installed on a given endpoint as of the time
the inventory is taken. Inventory data is considered to be an
"update" when the data is limited to documenting only the changes
that have occurred since the last complete inventory or update. Ad
hoc inventory data requests should also be supported; that is, an
inventory data consumer should be able to issue ad hoc queries to an
endpoint regarding specific identified products. Endpoints should be
able to indicate whether or not an identified product is installed,
and should be able to answer various questions about an installed
software product including: the date/time it was most recently
installed, removed or patched/updated, which patches are installed,
and the names and properties (e.g., versions, hashes) of files
associated with the product. Queries concerning the configuration of
installed software products are addressed separately in Section 7.
The author's vision rests on a model of the basic processes involved
in software product installation and maintenance. We use the term
"inventory event" to refer generically to any of three possible
events involving software which may occur on endpoints: (1)
installation (adding a software product to an endpoint's inventory),
(2) modification (changing any files associated with a previously-
installed product, and (3) removal (eliminating a software product
from an endpoint's inventory).
Under this model, each endpoint may support (but is not required to)
a resident "inventory manager". If present, the inventory manager is
an installed software product which provides a standard interface to
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"product installers", which are specialized software applications
that are designed to install, modify or remove other software
products on endpoints. Product installers are generally expected to
interact with the resident inventory manager, if one is present, but
are not required to. By interacting with the inventory manager,
product installers notify the inventory manager of any inventory
events they are generating, and supply data values needed to
characterize the event. When a product installer interacts correctly
with a resident inventory manager, we say that it has generated a
"conforming inventory event", meaning it has installed, modified or
removed a software product in a manner that conforms to the inventory
manager's expectations, as defined by its interface. When product
installers fail to interact properly with a resident inventory
manager, bypass it altogether, or when an inventory manager is not
resident, we say that the resulting inventory event is "non-
conforming". Additionally in the non-conforming case, a resident
inventory manager may also monitor a filesystem or other installation
contexts to detect changes to software to characterize the nature of
the change.
On Linux systems, RPM and DPKG are examples of inventory managers.
Each provides a standard product installer application which parses
specially-formatted package files, updates the RPM/APT database, and
copies files to their intended locations.
We require that when a product installer generates a conforming
inventory event, the resident inventory manager shall update a local
inventory data store on the endpoint. The local inventory data store
must maintain an up-to-date record of all software products installed
on the endpoint. The local inventory data store should also maintain
a record of all inventory events, including product modifications and
removals for later collection. The resident inventory manager should
have the ability to provide event-driven notification to other
software systems, to support reporting of inventory change events as
soon as they occur.
Because our model allows for non-conforming inventory events, as well
as for situations in which an endpoint does not support a resident
inventory manager, we allow for some number of "endpoint scanners" to
access endpoints either directly (by being resident on the endpoint
and by having the privileges necessary to inspect all areas of the
endpoint where installed software may be present) or indirectly
(e.g., by monitoring network traffic between the endpoint and other
devices), and attempt to infer inventory events which may have
happened at some point in the past.
Compiling a complete and accurate inventory of software products
installed on an endpoint thus involves collecting information about
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conforming as well as non-conforming inventory events. Information
about conforming inventory events is obtained from the resident
inventory manager, if present. Information about non-conforming
inventory events is obtained by running one or more endpoint
scanners. These tasks are performed by an "inventory producer",
which may or may not reside on an endpoint, but which is able to
interact with any resident inventory manager, as well as to initiate
scans using available endpoint scanners. Inventory producers
transmit collected inventory data to one or more inventory consumers,
which may store that data in repositories for later assessment,
perform assessments on that data directly, or both.
The collection and transmission of software inventory data is needed
to enable assessment of security posture attributes associated with
software inventory. For example, an enterprise may need to assess
compliance with "whitelists" (lists of software products authorized
for use on network devices) and "blacklists" (lists of specifically
prohibited products). For another example, an enterprise may need to
assess whether a software product with a publicly disclosed
vulnerability is installed on any endpoint within the network.
7.3. Software Management Process Operations
The following operations are necessary to carry out activities within
the Software Management domain:
1. Define Guidance: Add software to or remove software from one of
three lists for an endpoint. Those lists are software allowed to
be installed, software prohibited from being installed, and
software that is mandatory for installation.
2. Collect Inventory: Prepare and deliver a "complete" or "update"
inventory report to one or more interested inventory data
consumers, or respond to an ad hoc request for inventory data
about one or more software products.
3. Evaluate Software Inventory Posture: Based on guidance, evaluate
the current software inventory and determine compliance with
applicable security policies or identify conditions of interest.
4. Report Evaluation Results: Based on Guidance, report evaluation
results to interested report consumers.
7.4. Information Model Requirements
In this section we describe the data that enterprises will need to
carry out each Software Management operation.
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7.4.1. Define Guidance
The "Define Guidance" operation involves the Software Inventory
Collection and Evaluation Guidance Capabilities.
The Collection Guidance Capability generates or maintains the
guidance related to when Software Inventory should be collected
(e.g., periodic or when the inventory changes on an endpoint) and
what type of collection (partial or full) should occur at that time.
The Evaluation Guidance Capability generates or maintains the
guidance associated with software items where each item is
categorized as one of "mandatory", "optional", or "prohibited" for a
set of endpoints. A product is "mandatory" if it must be installed
on every compatible endpoint. A product is "optional" if it is
allowed to be installed on compatible endpoints. A product is
"prohibited" if it must not be installed on any compatible endpoints.
The Collection and Evaluation Guidance Capabilities have the
following information needs:
o (M) Unique Software Identifier: the software product which is the
subject of the request must be identified.
o (M) Authorization Status: the authorization status of the product
(one of 'mandatory', 'optional', or 'prohibited') must be
supplied.
o (O) Software Footprint: hashes of the software footprint (or a
pointer to those values) may be used to determine if software is
corrupted or tampered with.
This operation results in a change to the Collection or Evaluation
Guidance. This may, but need not, trigger an automatic enterprise-
wide assessment.
7.4.2. Collect Inventory
The "Collect Inventory" operation involves the following architecture
components:
o Software Inventory Collection Capability
o Software Inventory Collection Producers and Consumers
o Software Inventory Collection Guidance Capability
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The Software Inventory Collection Capability has the following
information needs:
o (M) Collection Guidance: the requester must indicate when to
perform a collection (e.g., at a set time, in response to a change
in inventory) and provide any other relevant guidance.
o (M) Request Type: the requester must indicate whether a "complete"
or "update" inventory should be performed and transmitted.
o (M) Unique Endpoint Identifier: the endpoint whose software
inventory data is to be collected must be identified.
o (M) Endpoint Software Inventory: a description of the current list
of software on the endpoint must be supplied.
At the completion of the Collect Inventory operation the Software
Inventory Producer will send an enumeration of installed software to
the appropriate Software Inventory Collection Consumer(s) or
Repositories.
7.4.3. Evaluate Software Inventory Posture
The "Evaluate Software Inventory Posture" operation involves the
following architecture components:
o Software Inventory Evaluation Capability
o Software Inventory Collection Consumers
o Software Inventory Evaluation Producers and Consumers
o Software Inventory Evaluation Guidance Capability
The Software Inventory Evaluation Capability is the component which
compares endpoint inventory information to current security guidance,
and notes any deviations from what is expected.
The Software Inventory Evaluation Capability has the following
information needs:
o (M) Endpoint Identifier: the endpoint whose inventory posture is
to be assessed must be identified.
o (M) Endpoint Software Inventory: a description of the current
software inventory of the endpoint must be supplied.
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o (M) Software Inventory Evaluation Guidance: all guidance pertinent
to performing an evaluation or assessment of software inventory
must be supplied.
o (M) Software Inventory Evaluation Results: the results from the
evaluation of the software inventory against the guidance.
The outcome of this operation is that the Software Inventory
Evaluation Capability identifies any deviations from guidance related
to the current inventory of software products installed on the
endpoint.
7.4.4. Report Evaluation Results
The "Report Evaluation Results" operation involves the following
architecture component:
o Software Inventory Results Report Capability
o Software Inventory Results Producers and Consumers
o Software Inventory Evaluation Consumer
o Software Inventory Reporting Guidance Capability
The Software Inventory Results Report Capability has the following
information needs:
o (M) Endpoint Identifier: the endpoint whose inventory posture
assessment is to be reported must be identified.
o (M) Software Inventory Reporting Guidance: all guidance pertinent
to generating and reporting software inventory assessment results
must be supplied.
o (M) Software Inventory Evaluation Results: the results from the
evaluation of the software inventory must be supplied.
o (M) Software Inventory Results Report: the report generated by
applying the reporting guidance to the evaluation results.
8. Configuration Management
This section presents an information model for the collection of
software configuration posture attributes. Software configuration
collection encompasses the subset of tasks within security automation
and continuous monitoring involved in the collection of important
settings from an endpoint and transmitting those settings to posture
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attribute data consumers that store the data and/or perform
enterprise-level security posture assessments.
For example, an operating system may enforce configurable password
complexity policies. As part of assessing the current complexity
requirements of an network of endpoints using this operating system,
a SACM tool will interact with the operating systems using a
standardized protocol to retrieve the value of the minimum password
length setting. This tool will then verify that each endpoint's
minimum password length setting meets (or potentially exceeds) the
organizational requirement, and will then report inconsistent
endpoints to the responsible administrator for action.
8.1. Core Information Needs
Unique Endpoint Identifier: We need to be able to relate the posture
attribute data and assessment results with an endpoint.
Configuration Item Identifier: We need to be able to uniquely
identify high-level, cross-platform, configuration statements
that can be interpreted and mapped to low-level, platform-
specific configuration settings by primary source vendors for
their platforms.
Platform Configuration Item Identifier(s): We need to know what low-
level configuration items map to the high-level configuration
items in order to collect posture attribute data from
specific platforms.
Posture Attributes: We need to be able to represent posture
attribute data collected from an endpoint for use in
assessments.
8.2. Process Area Description
In addition to the compilation of endpoint inventory data, there is a
need to compile and assess posture attribute values from an endpoint
to ensure that software on an endpoint has been configured correctly.
The configuration management security automation domain encompasses a
wide range of information needs to define, collect, and evaluate
posture attributes across a myriad of operating systems,
applications, and endpoint types. Configuration Management requires
that there is guidance about how and what to collect. The
establishment of all of this guidance is something that needs to be
done before the assessment trigger event, and needs to be done in a
way that can scale and be sustained over the lifecycle of the
applicable software products.
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8.2.1. The Existence of Configuration Item Guidance
The model for software configuration collection relies on two main
components: (1) the identification of software configuration items
and (2) the representation of posture attribute data from an
endpoint. For the identification of software configuration items,
the primary objective is for the security community to develop a
high-level, cross-platform identifier known as a "configuration item"
that can then be used by primary source vendors to map to low-level
configuration settings called "platform configuration items" for
their software. The benefits of this are that a single organization
is not responsible for maintaining the entire set of configuration
items for all platforms and the primary source vendors are given the
flexibility to determine what a particular configuration item means
for their software. From a practical perspective, this will likely
require a set of federated registries for both "configuration items"
and "platform configuration items". An example is the "configuration
item" that code should not automatically run when introduced into a
system without some entity intentionally invoking that operation.
One associated "platform configuration item" for Windows could be
disable autorun.
With regards to the model that represents posture attribute data from
an endpoint, there are three components: (1) the linking of posture
attribute data to the specific endpoint from which it was collected,
(2) a generic posture attribute that can be extended by primary
source vendors, and (3) the actual extensions of this generic posture
attribute by primary source vendors for their platforms. The first
component known as "collected posture attributes" associates the
posture attribute data collected from an endpoint with that endpoint
through the use of the Unique Endpoint Identifier previously
mentioned in this model. It may also include other metadata about
the collection such as the timestamp and what Posture Attribute
Producer was used. This model can be used as the payload for
messages of standardized protocols that are responsible for
transmitting and receiving posture attribute data between Posture
Attribute Producers and Consumers. The second component is the
"posture attribute" which provides metadata common to all posture
attributes regardless of how they are extended to meet the needs of a
particular platform. Finally, the third component is the "platform
posture attribute" which is left as an extension point for primary
source vendors to fulfill the posture attribute data needs for their
platforms. With this model, they can not only define the structure
of the posture attribute value data and the data type, but they can
also specify any additional metadata about the posture attribute that
they feel is relevant for posture attribute data consumers.
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8.2.2. Configuration Collection Guidance
Collection guidance provides instructions on how to collect posture
attributes from an endpoint and may include information such as a
list of posture attributes that may be collected, a list of posture
attributes to collect, and metadata that provides details on when and
how to collect posture attributes on an endpoint. The development of
this guidance is best performed by the primary source vendor who is
the most authoritative source of information for a specific platform.
However, if necessary, organizations can translate that information
into actionable collection guidance.
8.2.3. Configuration Evaluation Guidance
With the ability to identify and collect configuration items on an
endpoint, the next logical step is to assess the collected posture
attribute data against some known state or to check for some specific
conditions of interest. This will require the creation of evaluation
guidance. Evaluation guidance provides instructions on how to
evaluate collected posture attributes from an endpoint against a
known state or condition of interest. These instructions will
express policies and conditions of interest using logical constructs,
requirements for the data used during evaluation (age of data, source
of data, etc.), and references to human-oriented data that provides
technical, organizational, and other policy information.
The evaluation guidance will need to capture what posture attributes
to collect, how to collect the posture attributes (e.g., retrieve it
from a configuration database, a published source, or collect it by
leveraging collection guidance), any requirements on the usability of
the posture attribute data, and instructions on how to evaluate the
collected posture attribute data against defined policies or check
for a condition of interest. It may also include instructions on the
granularity of the results.
8.2.4. Local Configuration Management Process
Once an endpoint has been targeted for assessment, the first step
involves understanding what collection and evaluation guidance is
applicable to the endpoint.
After the applicable guidance has been retrieved, the collection of
posture attributes can begin. This operation may result in the
collection of a subset of posture attributes on the endpoint or all
of the posture attributes on the endpoint using a variety of
collection mechanisms.
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The three primary collection mechanisms include: (1) retrieving
posture attribute data from a enterprise repository, (2) software
publishing their posture attribute data, and (3) collecting the
posture attribute data from the endpoint or some intermediary. When
executing collection guidance, it may be necessary to use some
combination of these mechanisms to get all of the required data and
it may be necessary to authenticate with the endpoint, CMDB, or some
other data store.
In this model, a posture attribute producer may compile and transmit
posture attribute data to a posture attribute consumer on any of
these occasions: (1) upon request by a posture attribute consumer;
(2) on a predefined schedule (e.g. daily, weekly, etc.); or (3) after
some event has occurred (e.g. posture attribute value change
detected, etc.).
Once the posture attributes have been collected, evaluation guidance
is used to assess how the collected posture attribute data compares
with the predefined policies or whether or not the endpoint contains
conditions of interest. This operation may occur locally on the
endpoint or as part of an application that interacts with an
intermediate or back end server.
Once completed, the results of the evaluation can be transmitted to
the designated locations with the appropriate level of granularity
(e.g. results for individual "platform configuration items" or rolled
up results for a "configuration item", etc.). Depending on the
sensitivity of the evaluation results and collected posture attribute
data, it may be necessary for locations receiving the results to
authenticate with the sending endpoint and potentially even utilize a
secure communication channel.
Last in the configuration management lifecycle is the "adjudicate
further action" operation where the results are processed and it is
determined if follow up actions are necessary and by which parties.
Further actions could include modifying configuration settings,
expelling or quarantining an endpoint from the enterprise network,
removing or upgrading installed software, generating an alert,
documenting a compliance deviation, or performing some mitigation
among other things. This may also require re-initiating the
assessment process to ensure follow up actions were completed
successfully.
By clearly marking the line between collection and evaluation, tools
are free to implement these steps in the way that best suits the
needs of the end users and that allows for flexibility and
scalability across organizations of all size and shape.
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This model allows software and hardware vendors to publish posture
attributes in both proactive and reactive manners to centralized
repositories for evaluation. This type of flexibility is crucial for
scalable security automation in a large and diverse enterprise
environment. Finally, with this described model, key stakeholders
will be able to quickly and dynamically construct and execute new or
updated policy to enable fast and accurate posture evaluation.
Further, evaluation need not be constrained to a single repository of
information (be it an endpoint or a central repository). Evaluation
can occur across multiple repositories of information to reach an
aggregated decision on security posture.
8.3. Configuration Management Operations
The Configuration Management security automation domain includes all
of the processes involved in monitoring the configuration of
endpoints on an enterprise network. We have defined the following
operations within the configuration management domain:
1. Define Guidance: Define or acquire cross-platform configuration
item guidance, platform-specific configuration item guidance,
collection guidance, and evaluation guidance as applicable for
the endpoints that need to be assessed. This may also include
verifying the integrity of the guidance.
2. Collect Posture Attributes: Gather the needed posture attributes
from the endpoint and report them to one or more interested
posture attribute consumers. The collection of posture
attributes can be initiated by a number of triggers and can be
gathered using a variety of collection mechanisms.
3. Evaluate Posture Attributes: Based on guidance, assess the
collected posture attributes from the endpoint to determine
compliance with applicable security policies or identify
conditions of interest.
4. Report Evaluation Results: Based on guidance, transmit the
assessment results to interested report consumers with the
appropriate level of granularity.
8.4. Information Model Requirements
8.4.1. Define Guidance
The "Define Guidance" operation relies on the existence and
population of three types of guidance data: (1) configuration item
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guidance (cross-platform guidance and platform-specific guidance),
(2) collection guidance, and (3) evaluation guidance.
Therefore, the "Define Guidance" operation involves the Configuration
Item, Collection, Evaluation, and Reporting Guidance Capabilities
architecture components.
These components generate or store information about configuration
items and posture attributes, including when and how to collect them.
They also include how to evaluate the collected attributes and rules
around reporting the results for the desired configuration posture
assessments on applicable endpoints. Configuration Guidance
Capabilities can initiate requests to acquire guidance from existing
data stores or have the information manually added, modified, or
deleted.
To express configuration item guidance, the following information is
needed:
o (M) Configuration Item Identifier: A persistent, unique identifier
for the configuration item
o (M) Configuration Item Description: A high-level description of
the configuration item
To express platform configuration item guidance, the following
information may be needed ('M' indicates 'mandatory' and 'O'
indicates 'optional'):
o (M) Platform Configuration Item Identifier: A persistent, unique
identifier assigned by the primary source vendor
o (O) A reference to the unique, persistent configuration item
identifier
o (M) Platform Configuration Item Identifier Description: A low-
level description of the configuration item for the specific
platform
o (M) Posture Attributes: A list of posture attributes that
correspond to the platform configuration item
o (M) References that provide additional details about the platform
configuration item
o (O) Additional metadata that the primary source vendor feels is
relevant
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o (O) References to collection and evaluation guidance that they may
have developed or that someone else has developed on their behalf
To express "collection" guidance, the following information is
needed:
o (M) Listings of posture attribute identifiers for which values may
be collected and evaluated
o (M) Lists of attributes that are to be collected
o (O) Metadata that includes when to collect attributes (e.g. based
on interval, event, duration of collection), how and where to
collect the posture attribute data (e.g. CMDB, publish, collect
from endpoint or other data source, etc.)
To express "evaluation" guidance, the following information is
needed:
o (M) Logical constructs to express policies and conditions of
interest as well as the ability to ask different questions such as
"what is the value?", "is a configuration item compliant with a
policy?", etc.
o (M) Data requirements including the age of the data and the source
of the data among other things
o (O) References to human-oriented data that provides technical,
organizational, and other policy information
This operation results in a change in posture assessment guidance and
may, but need not, trigger an automatic enterprise-wide assessment.
8.4.2. Collect Posture Attributes Operation
The "Collect Posture Attributes" operation involves the following
architectural components:
o Configuration Collection Producers and Consumers
o Configuration Collection Capability
o Configuration Collection Guidance Capability
The Configuration Collection Capability has the following information
needs:
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o (M) Collection Guidance: the requester must indicate when to
perform a collection (e.g., at a set time, in response to a change
in inventory) and provide any other relevant guidance. This
guidance may include information such as what posture attributes
to collect, how to collect the posture attributes, and whether or
not the posture attribute data should be persisted for later use.
o (M) Request Type: the requester must indicate whether a "full" or
"partial" posture attribute collection should be performed.
o (M) Unique Endpoint Identifier: the endpoint whose posture
attribute data is to be collected must be identified.
o (M) Collected Posture Attributes: the collected posture attribute
data to include any required metadata.
At the completion of the Collect Posture Attributes operation the
Configuration Collection Producer will send the posture attributes
and their values to the appropriate Software Inventory Consumer(s) or
Repositories.
8.4.3. Evaluate Posture Attributes Operation
The "Evaluate Posture Attributes" operation involves the following
information elements:
o Configuration Evaluation Capability
o Configuration Collection Consumers
o Configuration Evaluation Producers and Consumers>
o Configuration Evaluation Guidance Capability
The Configuration Evaluation Capability is the component which
compares collected posture attribute data to current evaluation
guidance, and notes any deviations.
The Configuration Evaluation Capability has the following information
needs:
o (M) Unique Endpoint Identifier: the endpoint whose inventory
posture is to be assessed must be identified.
o (M) Collected Posture Attributes: the collected posture attribute
data to assess must be supplied or retrieved prior to performing
the assessment.
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o (M) Configuration Evaluation Guidance: all guidance pertinent to
performing an evaluation of posture attribute data must be
supplied.
o (M) Configuration Evaluation Results: the results from the
evaluation of the collected posture attributes against the
guidance.
8.4.4. Report Evaluation Results Operation
The "Report Evaluation Results" operation involves the following
architecture components:
o Configuration Results Report Capability
o Configuration Results Producers and Consumers
o Configuration Evaluation Consumers
o Configuration Reporting Guidance Capability
The Configuration Results Report Capability has the following
information needs:
o (M) Unique Endpoint Identifier: the endpoint whose posture
attribute evaluation results are to be reported must be
identified.
o (M) Posture Assessment Reporting Guidance: all guidance pertinent
to generating and reporting posture attribute evaluation results
must be supplied. This includes information such as the level of
granularity provided within the report (e.g. rolled up to the
"configuration item" level, at the "platform configuration level",
raw posture attribute data, or the results of evaluating the
posture attribute data against a known state), assurance of the
evaluation results, etc.
o (M) Configuration Evaluation Results: the results from the
evaluation of the collected posture attributes against the
guidance.
o (M) Configuration Results Report: the report generated by applying
the reporting guidance to the evaluation results.
The outcome of this operation is that the Configuration Results
Producer reports posture assessment results to interested
Configuration Results Consumers.
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9. Vulnerability Management
This section presents an information model for discovering extant
vulnerabilities within an enterprise network due to the presence of
installed software with publicly disclosed vulnerabilities.
Successful vulnerability management builds on the foundation laid by
endpoint management, software management, and configuration
management, discussed earlier. We limit the scope of vulnerability
management to the identification of vulnerable software. We do not
currently consider mitigation or remediation of identified
vulnerabilities within scope; these are important topics that deserve
careful attention. Furthermore, we recognize that the mere presence
of installed software with publicly disclosed vulnerabilities does
not necessarily mean than an enterprise network is vulnerable to
attack, as other defensive layers may effectively preclude exploits.
This will also need to be considered within the scope of an
information model that supports mitigation/remediation operations.
9.1. Core Information Needs
Unique Endpoint Identifiers: Each endpoint within the enterprise
network must have a unique identifier so we can relate
instances of vulnerable software to the endpoint(s) on which
they are installed.
Unique Software Identifiers: Organizations need to be able to
uniquely identify and label each software product installed
on an endpoint. This label must identify software to the
version/patch level and must have enough fidelity to be able
to associate it with other authoritative data (e.g., a
listing of the hashes of the executables that are associated
with the software).
Unique Vulnerability Identifiers: Organizations need to be able to
uniquely identify and label publicly disclosed software
vulnerabilities, and associate those labels with the unique
software identifiers of the software product(s) containing
those vulnerabilities.
9.2. Process Area Description
The authors envisage that software publishers produce "vulnerability
reports" about their products. They also envisage that each
"vulnerability report" is disseminated in a standard format suitable
for machine consumption and processing. Each vulnerability report
shall include, at a minimum, a unique identifier of the
vulnerability, and a machine-readable "applicability statement" which
associates the vulnerability with one or more software products and
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any pertinent product configuration information. One day, it will be
possible for a machine to authenticate the source of a vulnerability
report and confirm that the report has not been tampered with.
Each enterprise network shall support automated processes to
recognize when new vulnerability reports are available from software
publishers, and to retrieve and process those reports within the
context of the enterprise network.
The outcome of vulnerability management processes is the generation
of reports and/or alerts that identify vulnerable endpoints.
9.3. Vulnerability Management Process Operations
We have identified the following operations necessary to carry out
activities within the Vulnerability Management domain:
1. Collect Vulnerability Reports: Retrieve newly-published
vulnerability reports from software publishers.
2. Evaluate Vulnerability Posture: Based on guidance, assess the
current software inventory and configuration data and determine
compliance with applicable security policies or identify
conditions of interest.
3. Report Evaluation Results: Based on guidance, report evaluation
results to interested report consumers.
9.4. Information Model Requirements
In this section we describe the data that enterprises will need to
carry out each Vulnerability Management operation.
9.4.1. Collect Vulnerability Reports
The "Collect Vulnerability Reports" operation involves the following
architectural components:
o Vulnerability Collection Guidance Capability
o Vulnerability Evaluation Guidance Capability
The Vulnerability Collection Guidance Capability maintains a
repository of the guidance associated with what information and
attributes must be either collected or can be reused from other
posture assessment collection operations.
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The Vulnerability Evaluation Guidance Capability creates the
evaluation guidance associated with individual vulnerability reports.
Each vulnerability report documents a publicly disclosed software
vulnerability, and associates a unique vulnerability identifier with
one or more unique identifiers of affected software products.
The Vulnerability Evaluation Guidance Capability may be maintained by
a software publisher or it may be a repository that aggregates
vulnerability reports across multiple software publishers.
If it is an aggregate repository, it will also maintain a list of
publishers of vulnerability reports.
The Vulnerability Evaluation Guidance Capability may operate in
either (or both) "push" or "pull" modes. In "push" mode, publishers
of vulnerability reports initiate contact whenever a new report
becomes available. In "pull" mode, the Vulnerability Evaluation
Guidance Capability initiates contact with publishers, either on a
scheduled basis or in response to a request originating within the
enterprise network.
The Vulnerability Evaluation Guidance Capability has the following
information needs:
o (O) Publisher List: a new list of publishers may be supplied.
o (O) Update Schedule: a new schedule for pull-mode operations may
be supplied.
This operation may result in a change to the enterprise's collection
of vulnerability reports. This may, but need not, trigger an
automatic enterprise-wide vulnerability posture assessment.
9.4.2. Evaluate Vulnerability Posture
The "Evaluate Vulnerability Posture" operation involves the following
architectural components:
o Vulnerability Evaluation Capability
o Vulnerability Collection Guidance Capability
o Vulnerability Evaluation Guidance Capability
o Software Inventory Collection Producers
o Configuration Evaluation or Reporting Producers (when appropriate)
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o Vulnerability Evaluation Consumers
The Vulnerability Evaluation Capability is the component which
compares information about publicly disclosed software
vulnerabilities with current information about software installed
within the enterprise network. When a vulnerability can be mitigated
by a particular configuration, evaluation and/or reporting results
can be used to determine the vulnerability posture of the endpoint.
A vulnerability posture assessment may be triggered in response to
any of (a) the arrival of a new vulnerability report, (b) a change in
software inventory on any enterprise endpoint, or (c) a change in the
configuration of any software product installed on any enterprise
endpoint. This information is managed by the Vulnerability
Collection Guidance Capability.
The Vulnerability Evaluation Capability has the following information
needs:
o (M) Unique Vulnerability Identifier(s): the unique identifier of
the vulnerability to be reported on must be supplied.
o (M) Unique Endpoint Identifiers: the endpoints being assessed for
vulnerabilities must be identified.
o (M) Vulnerability Collection Guidance: all guidance pertinent to
determining what previously collected posture data to use must be
supplied.
o (M) Endpoint Software Inventory: a description of the current
software inventory of the endpoint must be supplied.
o (M) Configuration Evaluation Results: the results from the
evaluation of the collected posture attributes against the
guidance. OR (M) Configuration Results Report: the report
generated by applying the reporting guidance to the evaluation
results. Configuration Posture Assessment Results would only be
required when the vulnerability can be mitigated by configuring an
installed instance of software in a particular manner.
o (M) Vulnerability Evaluation Guidance: all guidance pertinent to
performing an evaluation of posture data must be supplied.
o (M) Vulnerability Evaluation Results: the results from the
evaluation of the collected posture data against the guidance.
The outcome of this operation is that a vulnerability report is
delivered to Vulnerability Evaluation Consumers.
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9.4.3. Report Evaluation Results
The "Report Evaluation Results" operation involves the following
architectural components:
o Vulnerability Results Report Capability
o Vulnerability Results Producers and Consumers
o Vulnerability Evaluation Consumers
o Vulnerability Reporting Guidance Capability
The Vulnerability Results Report Capability has the following
information needs:
o (M) Vulnerability Evaluation Results: the results from the
evaluation of the collected posture data against the guidance.
o (M) Unique Endpoint Identifiers: the vulnerable endpoints must be
identified.
o (M) Vulnerability Assessment Reporting Guidance: all guidance
pertinent to generating and reporting vulnerability assessment
results must be supplied (e.g., an alert should be generated).
o (M) Vulnerability Results Report: the report generated by applying
the reporting guidance to the evaluation results.
The outcome of this operation may be a report, an alert, or set of
reports and/or alerts, identifying any vulnerable endpoints within
the enterprise network.
10. From Information Needs to Information Elements
The previous sections highlighted information needs for a set of
management process areas that use posture assessment to achieve
organizational security goals. A single information need may be made
up of multiple information elements. Some information elements may
be required for two different process areas, resulting in two
different requirements. In an effort to support the main idea of
collect once and reuse the data to support multiple processes, we try
to define a singular set of information elements that will support
all the associated information needs.
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11. Information Model Elements
Traditionally, one would use the SACM architecture to define
interfaces that required information exchanges. Identified
information elements would then be based on those exchanges. Because
the SACM architecture document is still in the personal draft stage,
this information model uses a different approach to the
identification of information elements. First it lists the four main
endpoint posture assessment activities. Then it identifies
management process areas that use endpoint posture assessment to
achieve organizational security objectives. These process areas were
then broken down into operations that mirrored the typical workflow
from the SACM Use Cases draft [I-D.ietf-sacm-use-cases]. These
operations identify architectural components and their information
needs. In this section, information elements derived from those
information needs are mapped back to the four main activities listed
above.
The original liaison statement [IM-LIAISON-STATEMENT-NIST] requested
contributions for the SACM information model in the four areas
described below. Based on the capabilities defined previously in
this document, the requested areas alone do not provide a sufficient
enough categorization of the necessary information model elements.
The following sub-sections directly address the requested areas as
follows:
1. Endpoint Identification
A. Section 11.1 Asset Identifiers: Describes identification of
many different asset types including endpoints.
2. Endpoint Characterization
A. Section 11.3 Endpoint characterization: This directly maps to
the requested area.
3. Endpoint Attribute Expression/Representation
A. Section 11.4 Posture Attribute Expression: This corresponds
to the first part of "Endpoint Attribute Expression/
Representation."
B. Section 11.5 Actual Value Representation: This corresponds to
the second part of "Endpoint Attribute Expression/
Representation."
4. Policy evaluation expression and results reporting
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A. Section 11.6 Evaluation Guidance: This corresponds to the
first part of "Policy evaluation expression and results
reporting."
B. Section 11.7 Evaluation Result Reporting: corresponds to the
second part of "Policy evaluation expression and results
reporting."
Additionally, Section 11.2 Other Identifiers: describes other
important identification concepts that were not directly requested by
the liaison statement.
Per the liaison statement, each subsection references related work
that provides a basis for potential data models. Some analysis is
also included for each area of related work on how directly
applicable the work is to the SACM efforts. In general, much of the
related work does not fully address the general or use case-based
requirements for SACM, but they do contain some parts that can be
used as the basis for data models that correspond to the information
model elements. In these cases additional work will be required by
the WG to adapt the specification. In some cases, existing work can
largely be used in an unmodified fashion. This is also indicated in
the analysis. Due to time constraints, the work in this section is
very biased to previous work supported by the authors and does not
reflect a comprehensive listing. An attempt has been made where
possible to reference existing IETF work. Additional research and
discussion is needed to include other related work in standards and
technology communities that could and should be listed here. The
authors intend to continue this work in subsequent revisions of this
draft.
Where possible when selecting and developing data models in support
of these information model elements, extension points and IANA
registries SHOULD be used to provide for extensibility which will
allow for future data models to be addressed.
11.1. Asset Identifiers
In this context an "asset" refers to "anything that has value to an
organization" (see [NISTIR-7693]). This use of the term "asset" is
broader than the current definition in [I-D.ietf-sacm-terminology].
To support SACM use cases, a number of different asset types will
need to addressed. For each type of asset, one or more type of asset
identifier will be needed for use in establishing contextual
relationships within the SACM information model. The following asset
types are referenced or implied by the SACM use cases:
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Endpoint: Identifies an individual endpoint for which posture is
collected and evaluated.
Hardware: Identifies a given type of hardware that may be installed
within an endpoint.
Software: Identifies a given type of software that may be installed
within an endpoint.
Network: Identifies a network for which a given endpoint may be
connected or request a connection to.
Organization: Identifies an organizational unit.
Person: Identifies an individual, often within an organizational
context.
11.1.1. Related Work
11.1.1.1. Asset Identification
The Asset Identification specification [NISTIR-7693] is an XML-based
data model that "provides the necessary constructs to uniquely
identify assets based on known identifiers and/or known information
about the assets." Asset identification plays an important role in
an organization's ability to quickly correlate different sets of
information about assets. The Asset Identification specification
provides the necessary constructs to uniquely identify assets based
on known identifiers and/or known information about the assets.
Asset Identification provides a relatively flat and extensible model
for capturing the identifying information about a one or more assets,
and also provides a way to represent relationships between assets.
The model is organized using an inheritance hierarchy of specialized
asset types/classes (see Figure 4), providing for extension at any
level of abstraction. For a given asset type, a number of properties
are defined that provide for capturing identifying characteristics
and the referencing of namespace qualified asset identifiers, called
"synthetic IDs."
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The following figure illustrates the class hierarchy defined by the
Asset Identification specification.
asset
+-it-asset
| +-circuit
| +-computing-device
| +-database
| +-network
| +-service
| +-software
| +-system
| +-website
+-data
+-organization
+-person
Figure 4: Asset Identification Class Hierarchy
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This table presents a mapping of notional SACM asset types to those
asset types provided by the Asset Identification specification.
+--------------+------------------+---------------------------------+
| SACM Asset | Asset | Notes |
| Type | Identification | |
| | Type | |
+--------------+------------------+---------------------------------+
| Endpoint | computing-device | This is not a direct mapping |
| | | since a computing device is not |
| | | required to have network- |
| | | connectivity. Extension will be |
| | | needed to define a directly |
| | | aligned endpoint asset type. |
+--------------+------------------+---------------------------------+
| Hardware | Not Applicable | The concept of hardware is not |
| | | addressed by the asset |
| | | identification specification. |
| | | An extension can be created |
| | | based on the it-asset class to |
| | | address this concept. |
+--------------+------------------+---------------------------------+
| Software | software | Direct mapping. |
+--------------+------------------+---------------------------------+
| Network | network | Direct mapping. |
+--------------+------------------+---------------------------------+
| Organization | organization | Direct mapping. |
+--------------+------------------+---------------------------------+
| Person | person | Direct mapping. |
+--------------+------------------+---------------------------------+
Table 1: Mapping of SACM to Asset Identification Asset Types
This specification has been adopted by a number of SCAP validated
products. It can be used to address asset identification and
categorization needs within SACM with minor modification.
11.1.2. Endpoint Identification
An unique name for an endpoint. This is a foundational piece of
information that will enable collected posture attributes to be
related to the endpoint from which they were collected. It is
important that this name either be created from, provide, or be
associated with operational information (e.g., MAC address, hardware
certificate) that is discoverable from the endpoint or its
communications on the network. It is also important to have a method
of endpoint identification that can persist across network sessions
to allow for correlation of collected data over time.
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11.1.2.1. Related Work
The previously introduced asset identification specification (see
Section 11.1.1.1 provides a basis for endpoint identification using
the "computing-device" class. While the meaning of this class is
broader than the current definition of an endpoint in the SACM
terminology [I-D.ietf-sacm-terminology], either that class or an
appropriate sub-class extension can be used to capture identification
information for various endpoint types.
11.1.3. Software Identification
A unique name for a unit of installable software. Software names
should generally represent a unique release or installable version of
software. Identification approaches should allow for identification
of commercially available, open source, and organizationally
developed custom software. As new software releases are created, a
new software identifier should be created by the releasing party
(e.g., software creator, publisher, licensor). Such an identifier is
useful to:
o Relate metadata that describes the characteristics of the unit of
software, potentially stored in a repository of software
information. Typically, the software identifier would be used as
an index into such a repository.
o Indicate the presence of the software unit on a given endpoint.
o To determine what endpoints are the targets for an assessment
based on what software is installed on that endpoint.
o Define guidance related to a software unit that represents
collection, evaluation, or other automatable policies.
In general, an extensible method of software identification is needed
to provide for adequate coverage and to address legacy identification
approaches. Use of an IANA registry supporting multiple software
identification methods would be an ideal way forward.
11.1.3.1. Related Work
While we are not aware of a one-size-fits-all solution for software
identification, there are two existing specifications that should be
considered as part of the solution set. They are described in the
following subsections.
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11.1.3.1.1. Common Platform Enumeration
11.1.3.1.1.1. Background
The Common Platform Enumeration (CPE) [CPE-WEBSITE] is composed of a
family of four specification that are layered to build on lower-level
functionality. The following describes each specification:
1. CPE Naming: A standard machine-readable format [NISTIR-7695] for
encoding names of IT products and platforms. This defines the
notation used to encode the vendor, software name, edition,
version and other related information for each platform or
product. With the 2.3 version of CPE, a second, more advanced
notation was added to the original colon-delimited notation for
CPE naming.
2. CPE Matching: A set of procedures [NISTIR-7696] for comparing
names. This describes how to compare two CPE names to one
another. It describes a logical method that ensures that
automated systems comparing two CPE names would arrive at the
same conclusion.
3. CPE Applicability Language: An XML-based language [NISTIR-7698]
for constructing "applicability statements" that combine CPE
names with simple logical operators.
4. CPE Dictionary: An XML-based catalog format [NISTIR-7697] that
enumerates CPE Names and associated metadata. It details how to
encode the information found in a CPE Dictionary, thereby
allowing multiple organizations to maintain compatible CPE
Dictionaries.
The primary use case of CPE is for exchanging software inventory
data, as it allows the usage of unique names to identify software
platforms and products present on an endpoint. The NIST currently
maintains and updates a dictionary of all agreed upon CPE names, and
is responsible for ongoing maintenance of the standard. Many of the
names in the CPE dictionary have been provided by vendors and other
3rd-parties.
While the effort has seen wide adoption, most notably within the US
Government, a number of critical flaws have been identified. The
most critical issues associated with the effort are:
o Because there is no requirement for vendors to publish their own,
official CPE names, CPE necessarily requires one or more
organizations for curation. This centralized curation requirement
ensures that the effort has difficulty scaling.
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o Not enough primary source vendors provide platform and product
naming information. As a result, this pushes too much of the
effort out onto third-party groups and non-authoritative
organizations. This exacerbates the ambiguity in names used for
identical platforms and products and further reduces the utility
of the effort.
11.1.3.1.1.2. Applicability to Software Identification
The Common Platform Enumeration (CPE) Naming specification version
2.3 defines a scheme for human-readable standardized identifiers of
hardware and software products.
CPE names are the identifier format for software and hardware
products used in SCAP 1.2 and is currently adopted by a number of
SCAP product vendors.
CPE names can be directly referenced in the asset identification
software class (see Section 11.1.1.1.)
Although relevant, CPE has an unsustainable maintenance "tail" due to
the need for centralized curation and naming-consistency enforcement.
Its mention in this document is to support the historic inclusion of
CPE as part of SCAP and implementation of this specification in a
number of security processes and products. Going forward, software
identification (SWID) tags are recommended as a replacement for CPE.
To this end, work has been started to align both efforts to provide
translation for software units identified using SWID tags to CPE
Names. This translation would allow tools that currently use CPE-
based identifiers to map to SWID identifiers during a transition
period.
11.1.3.1.2. Software Identification (SWID) Tags
The software identification tag specification [ISO.19770-2] is an
XML-based data model that is used to describe a unit of installable
software. A SWID tag contains data elements that:
o Identify a specific unit of installable software,
o Enable categorization of the software (e.g., edition, bundle),
o Identification and hashing of software artifacts (e.g.,
executables, shared libraries),
o References to related software and dependencies, and
o Inclusion of extensible metadata.
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SWID tags can be associated with software installation media,
installed software, software updates (e.g., service packs, patches,
hotfixes), and redistributable components. SWID tags also provide
for a mechanism to relate these concepts to each other. For example,
installed software can be related back to the original installation
media, patches can be related to the software that they patch, and
software dependencies can be described for required redistributable
components. SWID tags are ideally created at build-time by the
software creator, publisher or licensor; are bundled with software
installers; and are deployed to an endpoint during software
installation.
SWID tags should be considered for two primary uses:
1. As the data format for exchanging descriptive information about
software products, and
2. As the source of unique identifiers for installed software.
In addition to usage for software identification, a SWID tag can
provide the necessary data needed to target guidance based on
included metadata, and to support verification of installed software
and software media using cryptographic hashes. This added
information increases the value of using SWID tags as part of the
larger security automation and continuous monitoring solution space.
11.1.4. Hardware Identification
Due to the time constraints, research into information elements and
related work for identifying hardware is not included in this
revision of the information model.
11.2. Other Identifiers
In addition to identifying core asset types, it is also necessary to
have stable, globally unique identifiers to represent other core
concepts pertaining to posture attribute collection and evaluation.
The concept of "global uniqueness" ensures that identifiers provided
by multiple organization do not collide. This may be handled by a
number of different mechanisms (e.g., use of namespaces).
11.2.1. Platform Configuration Item Identifier
A name for a low-level, platform-dependent configuration mechanism as
determined by the authoritative primary source vendor. New
identifiers will be created when the source vendor makes changes to
the underlying platform capabilities (e.g., adding new settings,
replacing old settings with new settings). When created each
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identifier should remain consistent with regards to what it
represents. Generally, a change in meaning would constitute the
creation of a new identifier.
For example, if the configuration item is for "automatic execution of
code", then the platform vendor would name the low-level mechanism
for their platform (e.g., autorun for mounted media).
11.2.1.1. Related Work
11.2.1.1.1. Common Configuration Enumeration
The Common Configuration Enumeration (CCE) [CCE] is an effort managed
by NIST. CCE provides a unique identifier for platform-specific
configuration items that facilitates fast and accurate correlation of
configuration items across multiple information sources and tools.
CCE does this by providing an identifier, a human readable
description of the configuration control, parameters needed to
implement the configuration control, various technical mechanisms
that can be used to implement the configuration control, and
references to documentation that describe the configuration control
in more detail.
By vendor request, NIST issues new blocks of CCE identifiers.
Vendors then populate the required fields and provided the details
back to NIST for publication in the "CCE List", a consolidated
listing of assigned CCE identifiers and associated data. Many
vendors also include references to these identifiers in web pages,
SCAP content, and prose configuration guides they produce.
CCE the identifier format for platform specific configuration items
in SCAP and is currently adopted by a number of SCAP product vendors.
While CCE is largely supported as a crowd-sourced effort, it does
rely on a central point of coordination for assignment of new CCE
identifiers. This approach to assignment requires a single
organization, currently NIST, to manage allocations of CCE
identifiers which doesn't scale well and introduces sustainability
challenges for large volumes of identifier assignment. If this
approach is used going forward by SACM, a namespaced approach is
recommended for identifier assignment that allows vendors to manage
their own namespace of CCE identifiers. This change would require
additional work to specify and implement.
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11.2.1.1.2. Open Vulnerability and Assessment Language
11.2.1.1.2.1. Background
The Open Vulnerability and Assessment Language (OVAL(R)) is an XML
schema-based data model developed as part of a public-private
information security community effort to standardize how to assess
and report upon the security posture of endpoints. OVAL provides an
established framework for making assertions about an endpoint's
posture by standardizing the three main steps of the assessment
process:
1. representing the current endpoint posture;
2. analyzing the endpoint for the presence of the specified posture;
and
3. representing the results of the assessment.
OVAL facilitates collaboration and information sharing among the
information security community and interoperability among tools.
OVAL is used internationally and has been implemented by a number of
operating system and security tools vendors.
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The following figure illustrates the OVAL data model.
+------------+
+-----------------+ | Variables |
| Common <---+ |
+--------> | +------------+
| | | +------------+
| | <---+ Directives |
| +--------^----^---+ | |
| | | +--------+---+
| | +-----+ |
| | | |
| +--------+--------+ | |
| | System | | |
| | Characteristics | | |
+------+------+ | | | +--------v---+
| Definitions | | | | | Results |
| | +--------^--------+ +-+ |
| | | | |
| | +------------+ |
+------^------+ +-------+----+
| |
+--------------------------------------+
Note: The direction of the arrows indicate a model dependency
Figure 5: The OVAL Data Model
The OVAL data model [OVAL-LANGUAGE], visualized in Figure 5, is
composed of a number of different components. The components are:
o Common: Constructs, enumerations, and identifier formats that are
used throughout the other model components.
o Definitions: Constructs that describe assertions about system
state. This component also includes constructs for internal
variable creation and manipulation through a variety of functions.
The core elements are:
* Definition: A collection of logical statements that are
combined to form an assertion based on endpoint state.
* Test(platform specific): A generalized construct that is
extended in platform schema to describe the evaluation of
expected against actual state.
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* Object(platform specific): A generalized construct that is
extended in platform schema to describe a collectable aspect of
endpoint posture.
* State(platform specific): A generalized construct that is
extended in platform schema to describe a set of criteria for
evaluating posture attributes.
o Variables: Constructs that allow for the parameterization of the
elements used in the Definitions component based on externally
provided values.
o System Characteristics: Constructs that represent collected
posture from one or more endpoints. This element may be embedded
with the Results component, or may be exchanged separately to
allow for separate collection and evaluation. The core elements
of this component are:
* CollectedObject: Provides a mapping of collected Items to
Objects defined in the Definitions component.
* Item(platform specific): A generalized construct that is
extended in platform schema to describe specific posture
attributes pertaining to an aspect of endpoint state.
o Results: Constructs that represent the result of evaluating
expected state (state elements) against actual state (item
elements). It includes the true/false evaluation result for each
evaluated Definition and Test. Systems characteristics are
embedded as well to provide low-level posture details.
o Directives: Constructs that enable result reporting detail to be
declared, allowing for result production to customized.
End-user organizations and vendors create assessment guidance using
OVAL by creating XML instances based on the XML schema implementation
of the OVAL Definitions model. The OVAL Definitions model defines a
structured identifier format for each of the Definition, Test,
Object, State, and Item elements. Each instantiation of these
elements in OVAL XML instances are assigned a unique identifier based
on the specific elements identifier syntax. These XML instances are
used by tools that support OVAL to drive collection and evaluation of
endpoint posture. When posture collection is performed, an OVAL
Systems Characteristics XML instance is generated based on the
collected posture attributes. When this collected posture is
evaluated, an OVAL Result XML instance is generated that contains the
results of the evaluation. In most implementations, the collection
and evaluation is performed at the same time.
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Many of the elements in the OVAL model (i.e., Test, Object, State,
Item) are abstract, requiring a platform-specific schema
implementation, called a "Component Model" in OVAL. These platform
schema implementations are where platform specific posture attributes
are defined. For each aspect of platform posture a specialized OVAL
Object, which appears in the OVAL Definitions model, provides a
format for expressing what posture attribute data to collect from an
endpoint through the specification of a datatype, operation, and
value(s) on entities that uniquely identify a platform configuration
item. For example, a hive, key, and name is used to identify a
registry key on a Windows endpoint. Each specialized OVAL Object has
a corresponding specialized State, which represents the posture
attributes that can be evaluated, and an Item which represents the
specific posture attributes that can be collected. Additionally, a
specialized Test exists that allows collected Items corresponding to
a CollectedObject to be evaluated against one or more specialized
States of the same posture type.
The OVAL language provides a generalized approach suitable for
posture collection and evaluation. While this approach does provide
for a degree of extensibility, there are some concerns that should be
addressed in order to make OVAL a viable basis for SACM's use. These
concerns include:
o Platform Schema Creation and Maintenance: In OVAL platform schema,
the OVAL data model maintains a tight binding between the Test,
Object, State, and Item elements used to assess an aspect of
endpoint posture. Creating a new platform schema or adding a new
posture aspect to an existing platform schema can be a very labor
intensive process. Doing so often involves researching and
understanding system APIs and can be prone to issues with
inconsistency within and between platforms. To simplify platform
schema creation and maintenance, the model needs to be evolved to
generalize the Test, Object, and State elements, requiring only
the definition of an Item representation.
o Given an XML instance based on the Definitions model, it is not
clear in the specification how incremental collection and
evaluation can occur. Because of this, typically, OVAL
assessments are performed on a periodic basis. The OVAL
specification needs to be enhanced to include specifications for
performing event-based and incremental assessment in addition to
full periodic collection.
o Defining new functions for manipulating variable values is current
handled in the Definitions schema. This requires revision to the
core language to add new functions. The OVAL specification needs
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to be evolved to provide for greater extensibility in this area,
allowing extension schema to define new functions.
o The current process for releasing a new version of OVAL, bundle
releases of the core language with release of community recognized
platform schema. The revision processes for the core and platform
schema need to be decoupled. Each platform schema should use some
mechanism to declare which core language version it relies on.
If adopted by SCAM, these issues will need to be addressed as part of
the SCAM engineering work to make OVAL more broadly adoptable as a
general purpose data model for posture collection and evaluation.
11.2.1.1.2.2. Applicability to Platform Configuration Item
Identification
Each OVAL Object is identified by a globally unique identifier. This
globally unique identifier could be used by the SACM community to
identify platform-specific configuration items and at the same time
serve as collection guidance. If used in this manner, OVAL Objects
would likely need to undergo changes in order to decouple it from
evaluation guidance and to provide more robust collection
capabilities to support the needs of the SACM community.
11.2.2. Configuration Item Identifier
An identifier for a high-level, platform-independent configuration
control. This identification concept is necessary to allow similar
configuration item concepts to be comparable across platforms. For
example, a configuration item might be created for the minimum
password length configuration control, which may then have a number
of different platform-specific configuration settings. Without this
type of identification, it will be difficult to perform evaluation of
expected versus actual state in a platform-neutral way.
High-level configuration items tend to change much less frequently
than the platform-specific configuration items (see Section 11.2.1)
that might be associated with them. To provide for the greatest
amount of sustainability, collections of configuration item
identifiers are best defined by specific communities of interest,
while platform-specific identifiers are best defined by the source
vendor of the platform. Under this model, the primary source vendors
would map their platform-specific configuration controls to the
appropriate platform-independent item allowing end-user organizations
to make use of these relationships.
To support different communities of interest, it may be necessary to
support multiple methods for identification of configuration items
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and for associating related metadata. Use of an IANA registry
supporting multiple configuration item identification methods would
be an ideal way forward. To the extent possible, a few number of
configuration item identification approaches is desirable, to
maximize the update by vendors who would be maintain mapping of
platform-specific configuration identifiers to the more general
platform-neutral configuration identifiers.
11.2.2.1. Related Work
11.2.2.1.1. Control Correlation Identifier
The Control Correlation Identifier (CCI) [CCI] is developed and
managed by the United States Department of Defense (US-DoD) Defense
Information Systems Agency (DISA). According to their website, CCI
"provides a standard identifier and description for each of the
singular, actionable statements that comprise an information
assurance (IA) control or IA best practice. CCI bridges the gap
between high-level policy expressions and low-level technical
implementations. CCI allows a security requirement that is expressed
in a high-level policy framework to be decomposed and explicitly
associated with the low-level security setting(s) that must be
assessed to determine compliance with the objectives of that specific
security control. This ability to trace security requirements from
their origin (e.g., regulations, IA frameworks) to their low-level
implementation allows organizations to readily demonstrate compliance
to multiple IA compliance frameworks. CCI also provides a means to
objectively roll-up and compare related compliance assessment results
across disparate technologies."
It is recommended that this approach be analysed as a potential
candidate for use as a configuration item identifier method.
Note: This reference to CCI is for informational purposes. Since the
editors do not represent DISA's interests, its inclusion in this
document does not indicate the presence or lack of desire to
contribute aspects of this effort to SACM.
11.2.2.1.2. A Potential Alternate Approach
There will likely be a desire by different communities to create
different collections of configuration item identifiers. This
fracturing may be caused by:
o Different requirements for levels of abstraction,
o Varying needs for timely maintenance of the collection, and
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o Differing scopes of technological needs.
Due to these and other potential needs, it will be difficult to
standardize around a single collection of configuration identifiers.
A workable solution will be one that is scalable and usable for a
broad population of end-user organizations. An alternate approach
that should be considered is the definition of data model that
contains a common set of metadata attributes, perhaps supported by an
extensible taxonomy, that can be assigned to platform-specific
configuration items. If defined at a necessary level of granularity,
it may be possible to query collections of platform-specific
configuration items provided by vendors to create groupings at
various levels of abstractions. By utilizing data provided by
vendors, technological needs and the timeliness of information can be
addressed based on customer requirements.
SACM should consider this and other approaches to satisfy the need
for configuration item roll-up in a way that provides the broadest
benefit, while achieving a sensible degree of scalability and
sustainability.
11.2.3. Vulnerability Identifier
An unique name for a known software flaw that exists in specific
versions of one or more units of software. One use of a
vulnerability identifier in the SACM context is to associate a given
flaw with the vulnerable software using software identifiers. For
this reason at minimum, software identifiers should identify a
software product to the patch or version level, and not just to the
level that the product is licensed.
11.2.3.1. Related Work
11.2.3.1.1. Common Vulnerabilities and Exposures
Common Vulnerabilities and Exposures (CVE) [CVE-WEBSITE] is a MITRE
led effort to assign common identifiers to publicly known security
vulnerabilities in software to facilitate the sharing of information
related to the vulnerabilities. CVE is the industry standard by
which software vendors, tools, and security professionals identify
vulnerabilities and could be used to address SACM's need for a
vulnerability identifier.
11.3. Endpoint characterization
Target when policies (collection, evaluated, guidance) apply
Collection can be used to further characterize
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Also human input
Information required to characterize an endpoint is used to determine
what endpoints are the target of a posture assessment. It is also
used to determine the collection, evaluation, and/or reporting
policies and the associated guidance that apply to the assessment.
Endpoint characterization information may be populated by:
o A manual input process and entered into records associated with
the endpoint, or
o Using information collected and evaluated by an assessment.
Regardless of the method of collection, it will be necessary to query
and exchange endpoint characterization information as part of the
assessment planning workflow.
11.3.1. Related Work
11.3.1.1. Extensible Configuration Checklist Description Format
11.3.1.1.1. Background
The Extensible Configuration Checklist Description Format (XCCDF) is
a specification that provides an XML-based format for expressing
security checklists. The XCCDF 1.2 specification is published by
International Organization for Standardization (ISO) [ISO.18180].
XCCDF contains multiple components and capabilities, and various
components align with different elements of this information model.
This specification was originally published by NIST [NISTIR-7275].
When contributed to ISO Joint Technical Committee 1 (JTC 1), a
comment was introduced indicating an interest in the IETF becoming
the maintenance organization for this standard. If the SACM working
group is interested in taking on engineering work pertaining to
XCCDF, a contribution through a national body can be made to create a
ballot resolution for transition of this standard to the IETF for
maintenance.
11.3.1.1.2. Applicability to Endpoint characterization
The target component of XCCDF provides a mechanism for capturing
characteristics about an endpoint including the fully qualified
domain name, network address, references to external identification
information (e.g. Asset Identification), and is extensible to
support other useful information (e.g. MAC address, globally unique
identifier, certificate, etc.). XCCDF may serve as a good starting
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point for understanding the types of information that should be used
to identify an endpoint.
11.3.1.2. Asset Reporting Format
11.3.1.2.1. Background
The Asset Reporting Format (ARF) [NISTIR-7694] is a data model to
express information about assets, and the relationships between
assets and reports. It facilitates the reporting, correlating, and
fusing of asset information within and between organizations. ARF is
vendor and technology neutral, flexible, and suited for a wide
variety of reporting applications.
There are four major sub-components of ARF:
o Asset: The asset component element includes asset identification
information for one or more assets. It simply houses assets
independent of their relationships to reports. The relationship
section can then link the report section to specific assets.
o Report: The report component element contains one or more asset
reports. An asset report is composed of content (or a link to
content) about one or more assets.
o Report-Request: The report-request component element contains the
asset report requests, which can give context to asset reports
captured in the report section. The report-request section simply
houses asset report requests independent of the report which was
subsequently generated.
o Relationship: The relationship component element links assets,
reports, and report requests together with well-defined
relationships. Each relationship is defined as {subject}
{predicate} {object}, where {subject} is the asset, report
request, or report of interest, {predicate} is the relationship
type being established, and {object} is one or more assets, report
requests, or reports.
11.3.1.2.2. Relationship to Endpoint Characterization
For Endpoint Characterization, ARF can be used in multiple ways due
to its flexibility. ARF supports the use of the Asset Identification
specification (more in Section 11.3.1.2.3) to embed the
representation of one or more assets as well as relationships between
those assets. It also allows the inclusion of report-requests, which
can provide details on what data was required for an assessment.
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ARF is agnostic to the data formats of the collected posture
attributes and therefore can be used within the SACM Architecture to
provide Endpoint Characterization without dictating data formats for
the encoding of posture attributes. The embedded Asset
Identification data model (see Section 11.1.1.1) can be used to
characterize one or more endpoints to allow targeting for collection,
evaluation, etc. Additionally, the report-request model can dictate
the type of reporting that has been requested, thereby providing
context as to which endpoints the guidance applies.
11.3.1.2.3. Asset Identification
Described earlier
In the context of Endpoint Characterization, the Asset Identification
data model could be used to encode information that identifies
specific endpoints and/or classes of endpoints to which a particular
assessment is relevant. The flexibility in the Asset Identification
specification allows usage of various endpoint identifiers as defined
by the SACM engineering work.
As stated in Section 11.3.1.2.3, the Asset Identification
specification is included within the Asset Reporting Framework (ARF)
and therefore can be used in concert with that specification as well.
11.3.1.3. The CPE Applicability Language
CPE described earlier
Applicability in CPE is defined as an XML language [NISTIR-7698] for
using CPE names to create applicability statements using logical
expressions. These expressions can be used to applicability
statements that can drive decisions about assets, whether or not to
do things like collect data, report data, and execute policy
compliance checks.
It is recommended that SACM evolve the CPE Applicability Language
through engineering work to allow it to better fit into the security
automation vision laid out by the Use Cases and Architecture for
SACM. This should include de-coupling the identification part of the
language from the logical expressions, making it such that the
language is agnostic to the method by which assets are identified.
This will allow use of SWID, CPE Names, or other identifiers to be
used, perhaps supported by an IANA registry of identifier types.
The other key aspect that should be evolved is the ability to make
use of the Applicability Language against a centralized repository of
collected posture attributes. The language should be able to make
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applicability statements against previously collected posture
attributes, such that an enterprise can quickly query the correct set
of applicable endpoints in an automated and scalable manner.
11.4. Posture Attribute Expression
Discuss the catalog concept. Listing of things that can be chosen
from. Things we can know about. Vendors define catalogs. Ways for
users to get vendor-provided catalogs.
To support the collection of posture attributes, there needs to be a
way for operators to identify and select from a set of platform-
specific attribute(s) to collect. The same identified attributes
will also need to be identified post-collection to associate the
actual value of that attribute pertaining to an endpoint as it was
configured at the time of the collection. To provide for
extensibility, the need exists to support a variety of possible
identification approaches. It is also necessary to enable vendors of
software to provide a listing, or catalog, of the available posture
attributes to operators that can be collected. Ideally, a federated
approach will be used to allow organizations to identify the location
for a repository containing catalogs of posture attributes provided
by authoritative primary source vendors. By querying these
repositories, operators will be able to acquire the appropriate
listings of available posture attributes for their deployed assets.
One or more posture attribute expressions are needed to support these
exchanges.
11.4.1. Related Work
The ATOM Syndication Format [RFC4287] provides an extensible,
flexible XML-based expression for organizing a collection of data
feeds consisting of entries. This standard can be used to express
one or more catalogs of posture attributes represented as data feeds.
Groupings of posture attributes would be represented as entries.
These entries could be defined using the data models described in the
"Related Work" sections below. Additionally, this approach can also
be used more generally for guidance repositories allowing other forms
of security automation guidance to be exchanged using the same
format.
11.4.2. Platform Configuration Attributes
A low-level, platform-dependent posture attribute as determined by
the authoritative primary source vendor. Collection guidance will be
derived from catalogs of platform specific posture attributes.
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For example, a primary source vendor would create a platform-specific
posture attribute that best models the posture attribute data for
their platform.
11.4.2.1. Related Work
11.4.2.1.1. Open Vulnerability and Assessment Language
A general overview of OVAL was provided previously in
Section 11.2.1.1.2.1. The OVAL System Characteristics platform
extension models provide a catalog of the posture attributes that can
be collected from an endpoint. In OVAL these posture attributes are
further grouped into logical constructs called OVAL Items. For
example, the passwordpolicy_item that is part of the Windows platform
extension groups together all the posture attributes related to
passwords for an endpoint running Windows (e.g. maximum password
age, minimum password length, password complexity, etc.). The
various OVAL Items defined in the OVAL System Characteristics may
serve as a good starting for the types of posture attribute data that
needs to be collected from endpoints.
OVAL platform extension models may be shared using the ATOM
Syndication Format.
11.4.2.1.2. Network Configuration Protocol and YANG Data Modeling
Language
The Network Configuration Protocol (NETCONF) [RFC6241] defines a
mechanism for managing and retrieving posture attribute data from
network infrastructure endpoints. The posture attribute data that
can be collected from a network infrastructure endpoint is highly
extensible and can defined using the YANG modeling language
[RFC6020]. Models exist for common datatypes, interfaces, and
routing subsystem information among other subjects. The YANG
modeling language may be useful in providing an extensible framework
for the SACM community to define one or more catalogs of posture
attribute data that can be collected from network infrastructure
endpoints.
Custom YANG modules may also be shared using the ATOM Syndication
Format.
11.4.2.1.3. Simple Network Management Protocol and Management
Information Base Entry
The Simple Network Protocol (SNMP) [RFC3411] defines a protocol for
managing and retrieving posture attribute data from endpoints on a
network . The posture attribute data that can be collected of an
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endpoint and retrieved by SNMP is defined by the Management
Information Base (MIB) [RFC3418] which is hierarchical collection of
information that is referenced using Object Identifiers . Given this,
MIBs may provide an extensible way for the SACM community to define a
catalog of posture attribute data that can be collected off of
endpoints using SNMP.
MIBs may be shared using the ATOM Syndication Format.
11.5. Actual Value Representation
Discuss instance concept.
The actual value of a posture attribute is collected or published
from an endpoint. The identifiers discussed previously provide names
for the posture attributes (i.e., software or configuration item)
that can be the subject of an assessment. The information items
listed below are the actual values collected during the assessment
and are all associated with a specific endpoint.
11.5.1. Software Inventory
A software inventory is a list of software identifiers (or content)
associated with a specific endpoint. Software inventories are
maintained in some organized fashion so that entities can interact
with it. Just having software publish identifiers onto an endpoint
is not enough, there needs to be an organized listing of all those
identifiers associated with that endpoint.
11.5.1.1. Related Work
11.5.1.1.1. Asset Summary Reporting
The Asset Summary Reporting (ASR) specification [NISTIR-7848]
provides a format for capturing summary information about one or more
assets. Specifically, it provides the ability to express a
collection of records from some defined data source and map them to
some set of assets. As a result, this specification may be useful
for capturing the software installed on an endpoint, its relevant
attributes, and associating it with a particular endpoint.
11.5.1.1.2. Software Identification Tags
SWID tag were previously introduced in Section 11.1.3.1.2. As stated
before, SWID tags are ideally deployed to an endpoint during software
installation. In the less ideal case, they may also be generated
based on information retrieved from a proprietary software
installation data store. At minimum, SWID tag must contain an
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identifier for each unit of installed software. Given this, SWID
tags may be a viable way for SACM to express detailed information
about the software installed on an endpoint.
11.5.2. Collected Platform Configuration Posture Attributes
Configurations associated with a software instance associated with an
endpoint
A list of the configuration posture attributes associated with the
actual values collected from the endpoint during the assessment as
required/expressed by any related guidance. Additionally, each
configuration posture attribute is associated with the installed
software instance it pertains to.
11.5.2.1. Related Work
11.5.2.1.1. Open Vulnerability and Assessment Language
A general overview of OVAL was provided previously in
Section 11.2.1.1.2.1. As mentioned earlier, the OVAL System
Characteristics platform extensions provide a catalog of the posture
attributes that can be collected and assessed in the form of OVAL
Items. These OVAL Items also serve as a model for representing
posture attribute data and associated values that are collected off
an endpoint. Furthermore, the OVAL System Characteristics model
provides a system_info construct that captures information that
identifies and characterizes the endpoint from which the posture
attribute data was collected. Specifically, it includes operating
system name, operating system version, endpoint architecture,
hostname, network interfaces, and an extensible construct to support
arbitrary additional information that may be useful in identifying
the endpoint in an enterprise such as information capture in Asset
Identification constructs. The OVAL System Characteristics model
could serve as a useful starting point for representing posture
attribute data collected from an endpoint although it may need to
undergo some changes to satisfy the needs of the SACM community.
11.5.2.1.2. NETCONF-Based Collection
Introduced earlier in Section 11.4.2.1.2, NETCONF defines a protocol
for managing and retrieving posture attribute data from network
infrastructure endpoints. NETCONF provides the <get-config> and
<get> operations to retrieve the configuration data, and
configuration data and state data respectively from a network
infrastructure endpoint. Upon successful completion of these
operations, the current posture attribute data of the network
infrastructure endpoint will be made available. NETCONF also
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provides a variety of filtering mechanisms (XPath, subtree, content
matching, etc.) to trim down the posture attribute data that is
collected from the endpoint. Given that NETCONF is widely adopted by
network infrastructure vendors, it may useful to consider this
protocol as a standardized mechanism for collecting posture attribute
data from network infrastructure endpoints.
As a side note, members of the OVAL Community have also developed a
proposal to extend the OVAL Language to support the assessment of
NETCONF configuration data [1]. The proposal leverages XPath to
extract the posture attribute data of interest from the XML data
returned by NETCONF. The collected posture attribute data can then
be evaluated using OVAL Definitions and the results of the evaluation
can be expressed as OVAL Results. While this proposal is not
currently part of the OVAL Language, it may be worth considering.
11.5.2.1.3. SNMP-Based Collection
The SNMP, previously introduced in Section 11.4.2.1.3, defines a
protocol for managing and retrieving posture attribute data from
endpoints on a network [RFC3411]. SNMP provides three protocol
operations [RFC3416] (GetRequest, GetNextRequest, and GetBulkRequest)
for retrieving posture attribute data defined by MIB objects. Upon
successful completion of these operations, the requested posture
attribute data of the endpoint will be made available to the
requesting application. Given that SNMP is widely adopted by
vendors, and the MIBs that define posture attribute data on an
endpoint are highly extensible, it may useful to consider this
protocol as a standardized mechanism for collecting posture attribute
data from endpoints in an enterprise.
11.6. Evaluation Guidance
11.6.1. Configuration Evaluation Guidance
The evaluation guidance is applied by evaluators during posture
assessment of an endpoint. This guidance must be able to reference
or be associated with the following previously defined information
elements:
o configuration item identifiers,
o platform configuration identifiers, and
o collected Platform Configuration Posture Attributes.
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11.6.1.1. Related Work
11.6.1.1.1. Open Vulnerability and Assessment Language
A general overview of OVAL was provided previously in
Section 11.2.1.1.2.1. The OVAL Definitions model provides an
extensible framework for making assertions about the state of posture
attribute data collected from an endpoint. Guidance written against
this model consists of one or more OVAL Tests, that can be logically
combined, where each OVAL Test defines what posture attributes should
be collected from an endpoint (as OVAL Objects) and optionally
defines the expected state of the posture attributes (as OVAL
States). While the OVAL Definitions model may be a useful starting
point for evaluation guidance, it will likely require some changes to
decouple collection and evaluation concepts to satisfy the needs of
the SACM community.
11.6.1.1.2. XCCDF Rule
A general description of XCCDF was provided in Section 11.3.1.1.1.
As noted there, an XCCDF document represents a checklist of items
against which a given endpoint's state is compared and evaluated. An
XCCDF Rule represents one assessed item in this checklist. A Rule
contains both a prose description of the assessed item (either for
presentation to the user in a tool's user interface, or for rendering
into a prose checklist for human consumption) and can also contain
instructions to support automated evaluation of the assessed item, if
such automated assessment is possible. Automated assessment
instructions can be provided either within the XCCDF Rule itself, or
by providing a reference to instructions expressed in other
languages, such as OVAL.
In order to support greater flexibility in XCCDF, checklists can be
tailored to meet certain needs. One way to do this is to enable or
disable certain rules that are appropriate or inappropriate to a
given endpoint, respectively. For example, a single XCCDF checklist
might contain check items to evaluate the configuration of an
endpoint's operating system. An endpoint deployed in an enterprise's
DMZ might need to be locked down more than a common internal
endpoint, due to the greater exposure to attack. In this case, some
operating system configuration requirements for the DMZ endpoint
might be unnecessary for the internal endpoint. Nonetheless, most
configuration requirements would probably remain applicable to both
environments (providing a common baseline for configuration of the
given operating system) and thus be common to the checking
instructions for both types of endpoints. XCCDF supports this by
allowing a single checklist to be defined, but then tailored to the
needs of the assessed endpoint. In the previous example, some Rules
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that apply only to the DMZ endpoint would be disabled during the
assessment of an internal endpoint and would not be exercised during
the assessment or count towards the assessment results. To
accomplish this, XCCDF uses the CPE Applicability Language. By
enhancing this applicability language to support other aspects of
endpoint characterization (see Section 11.3.1.3), XCCDF will also
benefit from these enhancements.
In addition, XCCDF Rules also support parameterization, allowing
customization of the expected value for a given check item. For
example, the DMZ endpoint might require a password of at least 12
characters, while an internal endpoint may only need 8 or more
characters in its password. By employing parameterization of the
XCCDF Rule, the same Rule can be used when assessing either type of
endpoint, and simply be provided with a different target parameter
each time to reflect the different role-based requirements. Sets of
customizations can be stored within the XCCDF document itself: XCCDF
Values store parameters values that can be used in tailoring, while
XCCDF Profiles store sets of tailoring instructions, including
selection of certain Values as parameters and the enabling and
disabling of certain Rules. The tailoring capabilities supported by
XCCDF allow a single XCCDF document to encapsulate configuration
evaluation guidance that applies to a broad range of endpoint roles.
11.7. Evaluation Result Reporting
11.7.1. Configuration Evaluation Results
The evaluation guidance applied during posture assessment of an
endpoint to customize the behavior of evaluators. Guidance can be
used to define specific result output formats or to select the level-
of-detail for the generated results. This guidance must be able to
reference or be associated with the following previously defined
information elements:
o configuration item identifiers,
o platform configuration identifiers, and
o collected Platform Configuration Posture Attributes.
11.7.1.1. Related Work
11.7.1.1.1. XCCDF TestResults
A general description of the eXtensible Configuration Checklist
Description Format (XCCDF) was provided in section
Section 11.3.1.1.1. The XCCDF TestResult structure captures the
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outcome of assessing a single endpoint against the assessed items
(i.e., XCCDF Rules) contained in an XCCDF instance document. XCCDF
TestResults capture a number of important pieces of information about
the assessment including:
o The identity of the assessed endpoint. See Section 11.3.1.1.2 for
more about XCCDF structures used for endpoint identification.
o Any tailoring of the checklist that might have been employed. See
Section 11.6.1.1.2 for more on how XCCDF supports tailoring.
o The individual results of the assessment of each enabled XCCDF
Rule in the checklist. See Section 11.6.1.1.2 for more on XCCDF
Rules.
The individual results for a given XCCDF Rule capture only whether
the rule "passed", "failed", or experienced some exceptional
condition, such as if an error was encountered during assessment.
XCCDF 1.2 Rule results do not capture the actual state of the
endpoint. For example, an XCCDF Rule result might indicate that an
endpoint failed to pass requirement that passwords be of a length
greater than or equal to 8, but it would not capture that the
endpoint was, in fact, only requiring passwords of 4 or more
characters. It may, however, be possible for a user to discover this
information via other means. For example, if the XCCDF Rule uses an
OVAL Definition to effect the Rule's evaluation, then the actual
endpoint state may be captured in the corresponding OVAL System
Characteristics file.
The XCCDF TestResult structure does provide a useful structure for
understanding the overall assessment that was conducted and the
results thereof. The ability to quickly determine the Rules that are
not complied with on a given endpoint allow administrators to quickly
identify where remediation needs to occur.
11.7.1.1.2. Open Vulnerability and Assessment Language
A general overview of OVAL was provided previously in
Section 11.2.1.1.2.1. OVAL Results provides a model for expressing
the results of the assessment of the actual state of the posture
attribute values collected of an endpoint (represented as an OVAL
System Characteristics document) against the expected posture
attribute values (defined in an OVAL Definitions document. Using
OVAL Directives, the granularity of OVAL Results can also be
specified. The OVAL Results model may be useful in providing a
format for capturing the results of an assessment.
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11.7.1.1.3. Asset Summary Reporting
A general overview of ASR was provided previously in
Section 11.5.1.1.1. As ASR provides a way to report summary
information about assets, it can be used within the SACM Architecture
to provide a way to aggregate asset information for later use. It
makes no assertions about the data formats used by the assessment,
but rather provides an XML, record-based way to collect aggregated
information about assets.
By using ASR to collect this summary information within the SACM
Architecture, one can provide a way to encode the details used by
various reporting requirements, including user-definable reports.
11.7.1.1.4. ARF
A general overview of ARF was provided previously in
Section 11.3.1.2.1. Because ARF is data model agnostic, it can
provide a flexible format for exchanging collection and evaluation
information from endpoints. It additionally provides a way to encode
relationships between guidance and assets, and as such, can be used
to associate assessment results with guidance. This could be the
guidance that directly triggered the assessment, or for guidance that
is run against collected posture attributes located in a central
repository.
11.7.2. Software Inventory Evaluation Results
The results of an evaluation of an endpoint's software inventory
against an authorized software list. The authorized software list
represents the policy for what software units are allowed,
prohibited, and mandatory for an endpoint.
12. Acknowledgements
Many of the specifications in this document have been developed in a
public-private partnership with vendors and end-users. The hard work
of the SCAP community is appreciated in advancing these efforts to
their current level of adoption.
Over the course of developing the initial draft, Brant Cheikes, Matt
Hansbury, Daniel Haynes, and Charles Schmidt have contributed text to
many sections of this document.
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13. IANA Considerations
This memo includes no request to IANA.
14. Security Considerations
Posture Assessments need to be performed in a safe and secure manner.
In that regard, there are multiple aspects of security that apply to
the communications between components as well as the capabilities
themselves. Due to time constraints, this information model only
contains an initial listing of items that need to be considered with
respect to security. This list is not exhaustive, and will need to
be augmented as the model continues to be developed/refined.
Initial list of security considerations include:
Authentication: Every component and asset needs to be able to
identify itself and verify the identity of other components
and assets.
Confidentiality: Communications between components need to be
protected from eavesdropping or unauthorized collection.
Some communications between components and assets may need to
be protected as well.
Integrity: The information exchanged between components needs to be
protected from modification. some exchanges between assets
and components will also have this requirement.
Restricted Access: Access to the information collected, evaluated,
reported, and stored should only be viewable/consumable to
authenticated and authorized entities.
15. References
15.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
15.2. Informative References
[CCE] The National Institute of Standards and Technology,
"Common Configuration Enumeration", 2014,
<http://nvd.nist.gov/CCE/>.
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[CCI] United States Department of Defense Defense Information
Systems Agency, "Control Correlation Identifier", 2014,
<http://iase.disa.mil/cci/>.
[CPE-WEBSITE]
The National Institute of Standards and Technology,
"Common Platform Enumeration", 2014,
<http://scap.nist.gov/specifications/cpe/>.
[CVE-WEBSITE]
The MITRE Corporation, "Common Vulnerabilities and
Exposures", 2014, <http://cve.mitre.org/about/>.
[I-D.camwinget-sacm-requirements]
Cam-Winget, N., "Secure Automation and Continuous
Monitoring (SACM) Requirements", draft-camwinget-sacm-
requirements-04 (work in progress), June 2014.
[I-D.ietf-sacm-terminology]
Waltermire, D., Montville, A., Harrington, D., and N. Cam-
Winget, "Terminology for Security Assessment", draft-ietf-
sacm-terminology-04 (work in progress), May 2014.
[I-D.ietf-sacm-use-cases]
Waltermire, D. and D. Harrington, "Endpoint Security
Posture Assessment - Enterprise Use Cases", draft-ietf-
sacm-use-cases-07 (work in progress), April 2014.
[IM-LIAISON-STATEMENT-NIST]
Montville, A., "Liaison Statement: Call for Contributions
for the SACM Information Model to NIST", May 2014,
<http://datatracker.ietf.org/liaison/1329/>.
[ISO.18180]
"Information technology -- Specification for the
Extensible Configuration Checklist Description Format
(XCCDF) Version 1.2", ISO/IEC 18180, 2013,
<http://standards.iso.org/ittf/PubliclyAvailableStandards/
c061713_ISO_IEC_18180_2013.zip>.
[ISO.19770-2]
"Information technology -- Software asset management --
Part 2: Software identification tag", ISO/IEC 19770-2,
2009.
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[NISTIR-7275]
Waltermire, D., Schmidt, C., Scarfone, K., and N. Ziring,
"Specification for the Extensible Configuration Checklist
Description Format (XCCDF) Version 1.2", NISTIR 7275r4,
March 2013, <http://csrc.nist.gov/publications/nistir/
ir7275-rev4/nistir-7275r4_updated-march-2012_clean.pdf>.
[NISTIR-7693]
Wunder, J., Halbardier, A., and D. Waltermire,
"Specification for Asset Identification 1.1", NISTIR 7693,
June 2011,
<http://csrc.nist.gov/publications/nistir/ir7693/
NISTIR-7693.pdf>.
[NISTIR-7694]
Halbardier, A., Waltermire, D., and M. Johnson,
"Specification for the Asset Reporting Format 1.1", NISTIR
7694, June 2011,
<http://csrc.nist.gov/publications/nistir/ir7694/
NISTIR-7694.pdf>.
[NISTIR-7695]
Cheikes, B., Waltermire, D., and K. Scarfone, "Common
Platform Enumeration: Naming Specification Version 2.3",
NISTIR 7695, August 2011,
<http://csrc.nist.gov/publications/nistir/ir7695/
NISTIR-7695-CPE-Naming.pdf>.
[NISTIR-7696]
Parmelee, M., Booth, H., Waltermire, D., and K. Scarfone,
"Common Platform Enumeration: Name Matching Specification
Version 2.3", NISTIR 7696, August 2011,
<http://csrc.nist.gov/publications/nistir/ir7696/
NISTIR-7696-CPE-Matching.pdf>.
[NISTIR-7697]
Cichonski, P., Waltermire, D., and K. Scarfone, "Common
Platform Enumeration: Dictionary Specification Version
2.3", NISTIR 7697, August 2011,
<http://csrc.nist.gov/publications/nistir/ir7697/
NISTIR-7697-CPE-Dictionary.pdf>.
[NISTIR-7698]
Waltermire, D., Cichonski, P., and K. Scarfone, "Common
Platform Enumeration: Applicability Language Specification
Version 2.3", NISTIR 7698, August 2011,
<http://csrc.nist.gov/publications/nistir/ir7698/
NISTIR-7698-CPE-Language.pdf>.
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[NISTIR-7848]
Davidson, M., Halbardier, A., and D. Waltermire,
"Specification for the Asset Summary Reporting Format
1.0", NISTIR 7848, May 2012,
<http://csrc.nist.gov/publications/drafts/nistir-7848/
draft_nistir_7848.pdf>.
[OVAL-LANGUAGE]
Baker, J., Hansbury, M., and D. Haynes, "The OVAL Language
Specification version 5.10.1", January 2012,
<https://oval.mitre.org/language/version5.10.1/>.
[RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An
Architecture for Describing Simple Network Management
Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
December 2002.
[RFC3416] Presuhn, R., "Version 2 of the Protocol Operations for the
Simple Network Management Protocol (SNMP)", STD 62, RFC
3416, December 2002.
[RFC3418] Presuhn, R., "Management Information Base (MIB) for the
Simple Network Management Protocol (SNMP)", STD 62, RFC
3418, December 2002.
[RFC3444] Pras, A. and J. Schoenwaelder, "On the Difference between
Information Models and Data Models", RFC 3444, January
2003.
[RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom
Syndication Format", RFC 4287, December 2005.
[RFC4949] Shirey, R., "Internet Security Glossary, Version 2", RFC
4949, August 2007.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the
Network Configuration Protocol (NETCONF)", RFC 6020,
October 2010.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
Bierman, "Network Configuration Protocol (NETCONF)", RFC
6241, June 2011.
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[SP800-117]
Quinn, S., Scarfone, K., and D. Waltermire, "Guide to
Adopting and Using the Security Content Automation
Protocol (SCAP) Version 1.2", SP 800-117, January 2012,
<http://csrc.nist.gov/publications/drafts/800-117-R1/
Draft-SP800-117-r1.pdf>.
[SP800-126]
Waltermire, D., Quinn, S., Scarfone, K., and A.
Halbardier, "The Technical Specification for the Security
Content Automation Protocol (SCAP): SCAP Version 1.2", SP
800-126, September 2011,
<http://csrc.nist.gov/publications/nistpubs/800-126-rev2/
SP800-126r2.pdf>.
15.3. URIs
[1] https://github.com/OVALProject/Sandbox/blob/master/x-netconf-
definitions-schema.xsd
Authors' Addresses
David Waltermire (editor)
National Institute of Standards and Technology
100 Bureau Drive
Gaithersburg, Maryland 20877
USA
Email: david.waltermire@nist.gov
Kim Watson
United States Department of Homeland Security
DHS/CS&C/FNR
245 Murray Ln. SW, Bldg 410
MS0613
Washington, DC 20528
USA
Email: kimberly.watson@hq.dhs.gov
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