SACM D. Haynes
Internet-Draft The MITRE Corporation
Intended status: Best Current Practice J. Fitzgerald-McKay
Expires: December 23, 2019 Department of Defense
L. Lorenzin
Pulse Secure
June 21, 2019
Endpoint Posture Collection Profile
draft-ietf-sacm-ecp-05
Abstract
This document specifies the Endpoint Posture Collection Profile,
which describes the best practices for the application of IETF, TNC,
and ISO/IEC data models, protocols, and interfaces to support the on-
going collection and communication of endpoint posture to a
centralized server where it can be stored and made available to other
tools. This document is an extension of the Trusted Computing
Group's Endpoint Compliance Profile Version 1.0 specification [ECP].
Status of This Memo
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 23, 2019.
Copyright Notice
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document authors. All rights reserved.
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publication of this document. Please review these documents
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carefully, as they describe your rights and restrictions with respect
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Endpoint Posture Collection Profile . . . . . . . . . . . . . 5
3.1. Components . . . . . . . . . . . . . . . . . . . . . . . 6
3.1.1. Endpoint . . . . . . . . . . . . . . . . . . . . . . 7
3.1.1.1. Posture Collection Engine . . . . . . . . . . . . 7
3.1.2. Posture Manager . . . . . . . . . . . . . . . . . . . 8
3.1.2.1. Posture Collection Manager . . . . . . . . . . . 8
3.1.3. Repository . . . . . . . . . . . . . . . . . . . . . 8
3.1.4. Evaluator . . . . . . . . . . . . . . . . . . . . . . 9
3.1.5. Orchestrator . . . . . . . . . . . . . . . . . . . . 9
3.1.6. Administrative Interface and API . . . . . . . . . . 9
3.2. Transactions . . . . . . . . . . . . . . . . . . . . . . 9
3.2.1. Provisioning . . . . . . . . . . . . . . . . . . . . 10
3.2.2. Discovery and Validation . . . . . . . . . . . . . . 10
3.2.3. Event Driven Collection . . . . . . . . . . . . . . . 10
3.2.4. Querying the Endpoint . . . . . . . . . . . . . . . . 10
3.2.5. Data Storage . . . . . . . . . . . . . . . . . . . . 10
3.2.6. Data Sharing . . . . . . . . . . . . . . . . . . . . 11
4. IETF NEA EPCP Implementation for Traditional Endpoints . . . 11
4.1. Endpoint Provisioning . . . . . . . . . . . . . . . . . . 13
4.2. Endpoint . . . . . . . . . . . . . . . . . . . . . . . . 13
4.2.1. Posture Collector . . . . . . . . . . . . . . . . . . 14
4.2.2. Posture Broker Client . . . . . . . . . . . . . . . . 14
4.2.3. Posture Transport Client . . . . . . . . . . . . . . 14
4.3. Posture Manager . . . . . . . . . . . . . . . . . . . . . 14
4.3.1. Posture Validator . . . . . . . . . . . . . . . . . . 14
4.3.2. Posture Broker Server . . . . . . . . . . . . . . . . 14
4.3.3. Posture Transport Server . . . . . . . . . . . . . . 14
4.4. Repository . . . . . . . . . . . . . . . . . . . . . . . 15
4.5. IETF SACM SWAM Extension to the IETF NEA EPCP
Implementation . . . . . . . . . . . . . . . . . . . . . 15
4.5.1. Endpoint Pre-Provisioning . . . . . . . . . . . . . . 15
4.5.2. SWID Tags . . . . . . . . . . . . . . . . . . . . . . 15
4.5.3. SWID Posture Collectors and Posture Validators . . . 15
4.5.3.1. The SWID Posture Collector . . . . . . . . . . . 16
4.5.3.2. The SWID Posture Validator . . . . . . . . . . . 16
4.5.4. Repository . . . . . . . . . . . . . . . . . . . . . 17
5. IETF NETCONF EPCP Implementation for Network Device Endpoints 17
5.1. Endpoint Provisioning . . . . . . . . . . . . . . . . . . 18
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5.2. Posture Manager Provisioning . . . . . . . . . . . . . . 18
5.3. Endpoint . . . . . . . . . . . . . . . . . . . . . . . . 18
5.3.1. Datastore . . . . . . . . . . . . . . . . . . . . . . 18
5.4. Posture Manager . . . . . . . . . . . . . . . . . . . . . 19
5.5. Repository . . . . . . . . . . . . . . . . . . . . . . . 19
6. Future Work . . . . . . . . . . . . . . . . . . . . . . . . . 19
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
9. Security Considerations . . . . . . . . . . . . . . . . . . . 22
9.1. Threat Model . . . . . . . . . . . . . . . . . . . . . . 22
9.1.1. Endpoint Attacks . . . . . . . . . . . . . . . . . . 23
9.1.2. Network Attacks . . . . . . . . . . . . . . . . . . . 23
9.1.3. Posture Manager Attacks . . . . . . . . . . . . . . . 23
9.1.4. Repository Attacks . . . . . . . . . . . . . . . . . 24
9.2. Countermeasures . . . . . . . . . . . . . . . . . . . . . 25
9.2.1. Countermeasures for Endpoint Attacks . . . . . . . . 25
9.2.2. Countermeasures for Network Attacks . . . . . . . . . 25
9.2.3. Countermeasures for Posture Manager Attacks . . . . . 26
9.2.4. Countermeasures for Repository Attacks . . . . . . . 26
10. Privacy Considerations . . . . . . . . . . . . . . . . . . . 27
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 27
11.1. Informative References . . . . . . . . . . . . . . . . . 27
11.2. Normative References . . . . . . . . . . . . . . . . . . 28
Appendix A. Rationale for an EPCP Solution . . . . . . . . . . . 30
A.1. Preventative Posture Assessments . . . . . . . . . . . . 30
A.2. All Network-Connected Endpoints are Endpoints . . . . . . 31
A.3. All Endpoints on the Network Must be Uniquely Identified 31
A.4. Standardized Data Models . . . . . . . . . . . . . . . . 31
A.5. Posture Information Must Be Stored . . . . . . . . . . . 32
A.6. Posture Information Can Be Shared . . . . . . . . . . . . 32
A.7. Enterprise Asset Posture Information Belongs to the
Enterprise . . . . . . . . . . . . . . . . . . . . . . . 32
Appendix B. EPCP Supported Use Cases and Non-Supported Use Cases 33
B.1. Supported Use Cases . . . . . . . . . . . . . . . . . . . 33
B.1.1. Hardware Asset Management . . . . . . . . . . . . . . 33
B.1.2. Software Asset Management . . . . . . . . . . . . . . 33
B.1.3. Vulnerability Management . . . . . . . . . . . . . . 34
B.1.4. Threat Detection and Analysis . . . . . . . . . . . . 34
B.2. Non-Supported Use Cases . . . . . . . . . . . . . . . . . 34
Appendix C. Endpoint Posture Collection Profile Examples . . . . 35
C.1. Continuous Posture Assessment of an Endpoint . . . . . . 35
C.1.1. Change on Endpoint Triggers Posture Assessment . . . 35
C.2. Administrator Searches for Vulnerable Endpoints . . . . . 38
Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 39
D.1. -04 to -05 . . . . . . . . . . . . . . . . . . . . . . . 39
D.2. -03 to -04 . . . . . . . . . . . . . . . . . . . . . . . 40
D.3. -02 to -03 . . . . . . . . . . . . . . . . . . . . . . . 40
D.4. -01 to -02 . . . . . . . . . . . . . . . . . . . . . . . 41
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D.5. -00 to -01 . . . . . . . . . . . . . . . . . . . . . . . 41
D.6. -01 to -02 . . . . . . . . . . . . . . . . . . . . . . . 41
D.7. -02 to -00 . . . . . . . . . . . . . . . . . . . . . . . 41
D.8. -00 to -01 . . . . . . . . . . . . . . . . . . . . . . . 41
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 41
1. Introduction
The Endpoint Posture Collection Profile (EPCP) builds on prior work
from the IETF NEA WG, the IETF NETCONF WG, IETF NETMOD WG, the
Trusted Computing Group (TCG) Trusted Network Communications [TNC]
WG, and the International Organization for Standardization/
International Electrotechnical Commission Joint Technical Committee
(JTC) 1, Subcommittee (SC) 7, WG 21 (ISO/IEC JTC 1, SC7, WG21) to
describe the best practices for the collection and communication of
posture information from network-connected endpoints to a centralized
server.
This document focuses on reducing the security exposure of a network
by enabling event-driven posture collection, standardized querying of
additional posture information as needed, and the communication of
that data to a centralized server where it can made available to
other components. Thus, eliminating the need for redundant
collection and agents on endpoints. Future revisions of this
document may include support for the collection of posture
information from other endpoint types as well as a standardized
interface for storing and querying data in repositories among other
capabilities. Additional information about this future work can be
found in Section 6 of this document.
To support the collection of posture information from new endpoint
types, this document is organized such that it first provides a high-
level overview of EPCP as well as its abstract architectural
components and transactions that will be realized by implementations
(Section 3). This is followed by individual sections that discuss
the best practices for specific implementations of the EPCP for a
given endpoint type (e.g., traditional, network device, etc.) along
with any extensions for supported use cases (software asset
management, vulnerability management, etc.).
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. This
specification does not distinguish blocks of informative comments and
normative requirements. Therefore, for the sake of clarity, note
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that lower case instances of must, should, etc. do not indicate
normative requirements.
Furthermore, this document uses terms as defined in
[I-D.ietf-sacm-terminology] unless otherwise specified.
3. Endpoint Posture Collection Profile
The EPCP describes how IETF, TCG, and ISO/IEC data models, protocols,
and interfaces can be used to support the posture assessment of
endpoints on a network. This profile does not generate new data
models, protocols, or interfaces; rather, it offers best practices
for a full end-to-end solution for posture assessment, as well as a
fresh perspective on how existing standards can be leveraged against
vulnerabilities. Rationale for the EPCP solution as well as the
supported and non-supported use cases is available in Appendix A and
Appendix B respectively.
The EPCP makes it possible to perform posture assessments against all
network-connected endpoints by:
1. uniquely identifying the endpoint;
2. collecting and evaluating posture based on data from the endpoint
(asset management, software asset management, vulnerability
management, and configuration management);
3. creating a secure, authenticated, confidential channel between
the endpoint and the posture manager;
4. enabling the endpoint to notify the posture manager about changes
to its configuration;
5. enabling the posture manager to request information about the
configuration of the endpoint; and
6. storing the posture information in a repository linked to the
identifier for the endpoint.
Furthermore, the EPCP aims to support data storage and data sharing
capabilities to make the collected posture information available to
authorized parties and components in support of other processes
(analytic, access control, remediation, reporting, etc.).
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3.1. Components
To perform posture assessment, data storage, and data sharing, the
EPCP defines several components. Some of these components reside on
the target endpoint. Others reside on a posture manager that manages
communications with the target endpoint and stores the target
endpoint's posture information in a repository.
It should be noted that the primary focus of this document is on the
communication between the posture manager and endpoints. While the
orchestrator, evaluator, repository, and administrative interface and
API will be discussed in the context of the broader EPCP
architecture, these components are not strictly defined nor are best
practices provided for them at this time. As a result, vendors are
free to implement these components and interfaces in a way that makes
the most sense for their products.
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*********FUTURE WORK********** Posture Manager Endpoint
* Orchestrator * +----------------+ +----------------+
* +--------+ * | | | |
* | |<------------>| | | |
* | | publish/ * | | | |
* | | subscribe * | | | |
* | | * | +------------+ | | +------------+ |
* +--------+ * | | | | | | | |
*********FUTURE WORK********** | | Posture | | report/ | | Posture | |
| | Collection | | publish | | Collection | |
Evaluator Repository | | Manager | |<----------| | Engine | |
+------+ +--------+ | | | | | | | |
| | | | | | | | | | | |
| | | | | +------------+ | | +------------+ |
| |<-------->| |<---------->| | query/ | |
| | request/ | | store | | subscribe | |
| | respond | | | |---------->| |
| | | | | | | |
+------+ +--------+ +----------------+ +----------------+
| ^ ^
| query | |
+----------------------------------------+ |
|
***************************FUTURE WORK***********|*************
* | *
* +--------------------------------+ *
* | Administrative Interface | *
* | and API | *
* +--------------------------------+ *
* *
***************************FUTURE WORK*************************
Figure 1: EPCP Components
3.1.1. Endpoint
An endpoint is defined in [RFC6876]. In the EPCP, the endpoint is
monitored by the enterprise and is the target of posture assessments.
To support these posture assessments, posture information is
collected via a posture collection engine.
3.1.1.1. Posture Collection Engine
The posture collection engine is located on the target endpoint and
can either receive queries for data from the posture collection
manager (see Section 3.2.4) or can push data to the posture
collection manager (see Section 3.2.3). The posture collection
engine sends collected posture information to the posture manager
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where it can be sanity checked and stored in the repository. The
posture collection engine also contains a capability that sets up
exchanges between the target endpoint and posture manager. This
capability makes the posture collection engine responsible for
performing the client-side portion of encryption handshakes, and for
locating authorized posture managers with which to communicate.
3.1.2. Posture Manager
The posture manager is an endpoint that collects, validates, and
enriches posture information received about a target endpoint. It
also stores the posture information it receives in the repository
where it can be evaluated. The posture manager does not evaluate the
posture information.
3.1.2.1. Posture Collection Manager
A posture collection manager is a lightweight and extensible
component that facilitates the coordination and execution of posture
collection requests using collection mechanisms deployed across the
enterprise. The posture collection manager may query and retrieve
guidance from the repository to guide the collection of posture
information from the target endpoint.
The posture collection manager also contains a capability that sets
up exchanges between the target endpoint and the posture manager, and
manages data sent to and from posture collection engine. It is also
responsible for performing the server-side portion of encryption
handshakes.
If the posture manager wants to register for continuous collection of
endpoint posture changes with the endpoint, then it must do so in a
scalable way. Specifically, it will need to create subscriptions
with endpoints in a way which allows the posture data to be securely
pushed. Effectively this means that the endpoint must be able to
establish secure transport connectivity to the posture collection
manager as needed, and the collection manager must be able to
periodically collect the current state of the endpoint to verify the
expected state of that endpoint.
3.1.3. Repository
The repository hosts guidance, endpoint identification information,
and posture information reported by target endpoints where it is made
available to authorized components and persisted over a period of
time set by the administrator. Information stored in the repository
will be accessible to authorized parties via a standard
administrative interface as well as through a standardized API. The
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repository may be a standalone component or may be located on the
posture manager. Furthermore, an implementation is not restricted to
a single repository and may leverage several repositories to provide
this functionality.
3.1.4. Evaluator
The evaluator assesses the posture status of a target endpoint by
comparing collected posture information against the desired state of
the target endpoint specified in guidance. The evaluator queries and
retrieves the appropriate guidance from the repository as well as
queries and retrieves the posture information required for the
assessment from the repository. If the required posture information
is not available in the repository, the evaluator may request the
posture information from the posture collection manager, which will
result in the collection of additional posture information from the
target endpoint. This information is subsequently stored in the
repository where it is made available to the evaluator and other
components. The results of the assessment are stored in the
repository where they are available to tools and administrators for
follow-up actions, further evaluation, and historical purposes.
3.1.5. Orchestrator
The orchestrator provides a publish/subscribe interface for the
repository so that infrastructure endpoints can subscribe to and
receive published posture assessment results from the repository
regarding endpoint posture changes.
3.1.6. Administrative Interface and API
The administrative interface allows administrators to query the
repository and manage the endpoints and software used in the EPCP via
the posture manager. Similarly, an API is necessary to allow
infrastructure endpoints and software access to the information
stored in the repository and to manage the endpoints and software
used in the EPCP. The administrative interface and API provide
authorized users, infrastructure endpoints, and software with the
ability to query the repository for data, send commands to the
posture collection managers requesting information from the
associated posture collection engines residing on endpoints, and
establish and update the policy that resides on the posture manager.
3.2. Transactions
The following sections describe the transactions associated with the
components of the EPCP architecture and may be provided in an
implementation.
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3.2.1. Provisioning
An endpoint is provisioned with one or more attributes that will
serve as its unique identifier on the network as well as the
components and data models necessary to interact with the posture
manager. Examples of such identifiers include MAC addresses, serial
numbers, hardware certificates compliant with [IEEE-802-1ar], and the
identities of hardware cryptographic modules among others. Once
provisioning is complete, the endpoint is deployed on the network.
Over time, components and data models may need to be added to the
endpoint or updated to support the collection needs of an enterprise.
3.2.2. Discovery and Validation
If necessary, the target endpoint finds and validates the posture
manager. The posture collection engine on the target endpoint and
posture collection manager on the posture manager complete an
encryption handshake, during which endpoint identity information is
exchanged.
3.2.3. Event Driven Collection
The posture assessment is initiated when the posture collector engine
on the target endpoint notices that relevant posture information on
the endpoint has changed. Then, the posture collection engine
initiates a posture assessment information exchange with the posture
collection manager.
3.2.4. Querying the Endpoint
The posture assessment is initiated by the posture collection
manager. This can occur because:
1. policy states that a previous assessment has aged out or become
invalid, or
2. the posture collection manager is alerted by a sensor or an
administrator (via the posture manager's administrative
interface) that an assessment must be completed.
3.2.5. Data Storage
Once posture information is received by the posture manager, it is
forwarded to the repository. The repository could be co-located with
the posture manager, or there could be direct or brokered
communication between the posture manager and the repository. The
posture information is stored in the repository along with past
posture information collected about the target endpoint.
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3.2.6. Data Sharing
Because the target endpoint posture information was sent in
standards-based data models over secure, standardized protocols, and
then stored in a centralized repository linked to unique endpoint
identifiers, authorized parties are able to access the posture
information. Such authorized parties may include, but are not
limited to, administrators or endpoint owners (via the posture
manager's administrative interface), evaluators that access the
repository directly, and orchestrators that rely on publish/subscribe
communications with the repository.
4. IETF NEA EPCP Implementation for Traditional Endpoints
When EPCP is used, posture collectors running on the target endpoint
gather posture information as changes occur on the endpoint. The
data is aggregated by the posture broker client and forwarded to a
posture manager, over a secure channel, via the posture transport
client. Once received by the posture transport server on the posture
manager, the posture information is directed by the posture broker
server to the appropriate posture validators where it can be
processed and stored in a repository. There the posture information
can be used by other tools to carry out assessment tasks. Posture
collectors can also be queried by posture validators to refresh
posture information about the target endpoint or to ask a specific
question about posture information. This is shown in Figure 2.
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Posture Posture
Collection Collection
Manager Engine
+---------------+ +---------------+
| | | |
| +-----------+ | PA-TNC | +-----------+ |
| | Posture | |--------| | Posture | |
| | Validator | | | | Collector | |
| +-----------+ | | +-----------+ |
| | | | | |
| | IF-IMV | | | IF-IMC |
| | | | | |
| +-----------+ | PB-TNC | +-----------+ |
| | PB Server | |--------| | PB Client | |
| +-----------+ | | +-----------+ |
| | | | | |
| | | | | |
| | | | | |
| +-----------+ | | +-----------+ |
| | PT Server | |<------>| | PT Client | |
| +-----------+ | PT-TLS | +-----------+ |
| | | |
+---------------+ +---------------+
Figure 2: NEA Components
These requirements are written with a view to performing a posture
assessment on an endpoint; as the EPCP grows and evolves, these
requirements will be expanded to address issues that arise. Note
that these requirements refer to defined components of the NEA
architecture [RFC5209]. As with the NEA architecture, vendors have
discretion as to how these NEA components map to separate pieces of
software or endpoints.
Furthermore, it should be noted that the posture broker client and
posture transport client components of the posture collection engine
and the posture broker server and posture transport server components
of the posture collection manager would likely need to be implemented
by a single vendor because there are no standardized interfaces
between the respective components and would not be interoperable.
Examples of the EPCP as implemented using the components from the NEA
architecture are provided in Appendix C.
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4.1. Endpoint Provisioning
An endpoint is provisioned with a machine certificate that will serve
as its unique identifier on the network as well as the components
necessary to interact with the posture manager. This includes a
posture collection engine to manage requests from the posture manager
and the posture collectors necessary to collect the posture
information of importance to the enterprise. The endpoint is
deployed on the network.
The target endpoint SHOULD authenticate to the posture manager using
a machine certificate during the establishment of the outer tunnel
achieved with the posture transport protocol defined in [RFC6876].
[IF-IMV] specifies how to pull an endpoint identifier out of a
machine certificate. An endpoint identifier SHOULD be created in
conformance with [IF-IMV] from a machine certificate sent via
[RFC6876].
In the future, the identity could be a hardware certificate compliant
with [IEEE-802-1ar]; ideally, this identifier SHOULD be associated
with the identity of a hardware cryptographic module, in accordance
with [IEEE-802-1ar], if present on the endpoint. The enterprise
SHOULD stand up a certificate root authority; install its root
certificate on endpoints and on the posture manager; and provision
the endpoints and the posture manager with machine certificates. The
target endpoint MAY authenticate to the posture manager using a
combination of the machine account and password; however, this is
less secure and not recommended.
4.2. Endpoint
The endpoint MUST conform to [RFC5793], which levies several
requirements against the endpoint. An endpoint that complies with
these requirements will be able to:
1. attempt to initiate a session with the posture manager if the
posture makes a request to send an update to posture manager;
2. notify the posture collector if no PT-TLS session with the
posture manager can be created;
3. notify the posture collector when a PT-TLS session is
established; and
4. receive information from the posture collectors, forward this
information to the posture manager via the posture collection
engine.
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4.2.1. Posture Collector
Any posture collector used in an EPCP solution MUST be conformant
with the TCG TNC Integrity Measurement Collector interface [IF-IMC].
4.2.2. Posture Broker Client
The posture broker client MUST conform to [IF-IMC] to enable
communications between the posture broker client and the posture
collectors on the endpoint.
4.2.3. Posture Transport Client
The posture transport client MUST implement PT-TLS.
The posture transport client MUST support the use of machine
certificates for TLS at each endpoint consistent with the
requirements stipulated in [RFC6876] and [Server-Discovery].
The posture transport client MUST be able to locate an authorized
posture manager, and switch to a new posture manager when required by
the network, in conformance with [Server-Discovery].
4.3. Posture Manager
The posture manager MUST conform to all requirements in the
[RFC5793].
4.3.1. Posture Validator
Any posture validator used in an EPCP solution MUST be conformant
with the TCG TNC Integrity Measurement Verifier interface [IF-IMV].
4.3.2. Posture Broker Server
The posture broker server MUST conform to [IF-IMV]. Conformance to
[IF-IMV] enables the posture broker server to obtain endpoint
identity information from the posture transport server, and pass this
information to any posture validators on the posture manager.
4.3.3. Posture Transport Server
The posture transport server MUST implement PT-TLS.
The posture transport server MUST support the use of machine
certificates for TLS at each endpoint consistent with the
requirements stipulated in [RFC6876] and [Server-Discovery].
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4.4. Repository
EPCP requires a simple administrative interface for the repository.
Posture validators on the posture manager receive the target endpoint
posture information via PA-TNC [RFC5792] messages sent from
corresponding posture collectors on the target endpoint. The posture
validators store this information in the repository linked to the
identity of the target endpoint where the posture collectors are
located.
4.5. IETF SACM SWAM Extension to the IETF NEA EPCP Implementation
This section defines the requirements associated with the software
asset management extension [RFC8412] to the IETF NEA EPCP
implementation.
4.5.1. Endpoint Pre-Provisioning
This section defines the requirements associated with implementing
SWIMA.
The following requirements assume that the platform or OS vendor
supports the use of SWID tags and has identified a standard directory
location for the SWID tags to be located as specified by [SWID].
4.5.2. SWID Tags
The primary content for the EPCP is the information conveyed in the
elements of a SWID tag.
The endpoint MUST have SWID tags stored in a directory specified in
[SWID]. The tags SHOULD be provided by the software vendor; they MAY
also be generated by:
o the software installer; or
o third-party software that creates tags based on the applications
it sees installed on the endpoint.
The elements in the SWID tag MUST be populated as specified in
[SWID]. These tags, and the directory in which they are stored, MUST
be updated as software is added, removed, or updated.
4.5.3. SWID Posture Collectors and Posture Validators
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4.5.3.1. The SWID Posture Collector
For the EPCP, the SWID posture collector MUST be conformant with
[RFC8412], which includes requirements for:
1. Collecting SWID tags from the SWID directory;
2. Monitoring the SWID directory for changes;
3. Initiating a session with the posture manager to report changes
to the directory;
4. Maintaining a list of changes to the SWID directory when updates
take place and no PT-TLS connection can be created with the
posture manager;
5. Responding to a request for SWID tags from the SWID Posture
Validator on the posture manager; and
6. Responding to a query from the SWID posture validator as to
whether all updates have been sent.
The SWID posture collector is not responsible for detecting that the
SWID directory was not updated when an application was either
installed or uninstalled.
4.5.3.2. The SWID Posture Validator
Conformance to [RFC8412] enables the SWID posture validator to:
1. Send messages to the SWID posture collector (at the behest of the
administrator at the posture manager console) requesting updates
for SWID tags located on endpoint;
2. Ask the SWID posture collector whether all updates to the SWID
directory located at the posture manager have been sent; and
3. Perform any validation and processing on the collected SWID
posture information prior to storage.
In addition to these requirements, a SWID posture validator used in
conformance with this profile MUST be capable of passing this SWID
posture information as well as the associated endpoint identity to
the repository for storage.
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4.5.4. Repository
The administrative interface SHOULD enable an administrator to:
1. Query which endpoints have reported SWID tags for a particular
application
2. Query which SWID tags are installed on an endpoint; and
3. Query tags based on characteristics, such as vendor, publisher,
etc.
5. IETF NETCONF EPCP Implementation for Network Device Endpoints
When EPCP is used, a NETCONF client that implements the posture
collection manager sends a query to target network device endpoint
requesting posture information over a secure channel. Once the
NETCONF server on the endpoint receives the request, it queries one
or more datastores for the posture information. The NETCONF server
then reports the information back to the NETCONF client where it can
be stored in a repository for use by other tools. This is shown in
Figure 3.
Posture Posture
Collection Collection
Manager Engine
+---------------+ +---------------+
| | | |
| | | +-----------+ |
| | | | Data | |
| | | | Store(s) | |
| | | +-----------+ |
| | | | |
| | | | |
| +-----------+ | | +-----------+ |
| | NETCONF | | | | NETCONF | |
| | Client | |<------->| | Server | |
| +-----------+ | NETCONF | +-----------+ |
| | | |
+---------------+ +---------------+
Figure 3: NETCONF Components
These requirements are written with a view to performing a posture
assessment on network device endpoints (routers, switches, etc.); as
the EPCP grows and evolves, these requirements will be expanded to
address issues that arise.
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Note that these requirements refer to defined components of the
NETCONF architecture and map back to EPCP. As with the NETCONF
architecture, vendors have discretion as to how these NETCONF
components map to separate pieces of software or endpoints.
5.1. Endpoint Provisioning
For the posture manager to be able to query the datastores on the
endpoint, the endpoint MUST be configured to grant the posture
manager access to its datastores as described in [RFC6241]. The
posture manager is identified by its NETCONF username. The endpoint
is deployed on the network.
5.2. Posture Manager Provisioning
For the posture manager to be able to query the datastores on the
endpoint, the posture manager MUST be provisioned with a NETCONF
username that will be used to authenticate the posture manager to the
endpoint as described in [RFC6241]. The username generated will be
determined by the selected transport protocol. The posture manager
is deployed on the network.
5.3. Endpoint
An endpoint MUST conform to the requirements outlined for servers in
the NETCONF protocol as defined in [RFC6241]. This requires the
implementation of NETCONF over SSH [RFC6242]. An endpoint MAY
support the NETCONF protocol over other transports such as TLS
[RFC7589] as well as the RESTCONF protocol as defined in [RFC8040].
5.3.1. Datastore
A NETCONF datastore on an endpoint MUST support the operations
outlined in [RFC6241], but, the actual implementation of the
datastore is left to the endpoint vendor.
Datastores MUST support the YANG data modeling language [RFC7950] for
expressing endpoint posture information in a structured format. In
addition, datastores MAY support other data models such as XML (via
YIN) for representing posture information.
Datastores MUST support the compliance posture information specified
in [RFC7317]. Datastores MAY support other models standardized or
proprietary as deemed appropriate by the endpoint vendor.
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5.4. Posture Manager
A posture manager MUST conform to the requirements specified for
clients in the NETCONF protocol as defined in [RFC6241]. This
requires the implementation of NETCONF over SSH [RFC6242]. A posture
manager MAY also support the NETCONF protocol over other transports
such as TLS [RFC7589]. In addition, a posture manager MAY support
the RESTCONF protocol as defined in [RFC8040].
While ad-hoc fetch/polling via NETCONF and RESTCONF is useful for
assessing endpoint compliance, such solutions by themselves are not
able to detect changes as they occur on the endpoint. As a result, a
future revision of this document will support
[I-D.ietf-netconf-yang-push] to receive updates on YANG-modeled
posture information. Similarly, because not all posture information
is modeled in YANG, a future revision of this document will reference
[I-D.ietf-netconf-subscribed-notifications] once it is a standard to
support continuous streams of unstructured data from the endpoint to
the posture manager.
5.5. Repository
EPCP requires a simple administrative interface for the repository.
The posture collection manager on the posture manager receives the
target endpoint posture information via NETCONF [RFC6241] messages
sent from posture collection engine on the target endpoint. The
posture collection manager stores this information in the repository
linked to the identity of the target endpoint from which it was
collected.
6. Future Work
This section captures ideas for future work related to EPCP that
might be of interest to the IETF SACM WG. These ideas are listed in
no particular order.
o The [I-D.ietf-netconf-subscribed-notifications] and
[I-D.ietf-netconf-yang-push] which have been submitted to IESG for
publication could be leveraged for an HTTP-based subscription for
EPCP. Specifically, it could be used for the posture collection
manager to continuously receive posture changes as they happen
from the posture collection engine. At this point, it seems like
[I-D.ietf-netconf-restconf-notif] would be a good match to these
requirements. However further investigation into the
applicability of supporting a RESTCONF server capability on to
handle subscription requests needs to be made. Specific questions
which should be examined include:
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* Number of endpoints which can be continuously tracked by a
single posture collection manager. Scalability questions to be
considered include elements from the number of transport
connects maintained to the volume of volume and churn of
posture evidence which will be continuously pushed to the
posture collection manager manager.
* Ability of the posture collection manager to establish and
maintain a continuous state of endpoint posture during
failures. This includes failures/reboots on either side of the
interface.
* Ability to support for the full set of functions described for
NETCONF within Section 5.
o Add support endpoint types beyond workstations, servers, and
network infrastructure devices.
o Examine the integration of [I-D.ietf-mile-xmpp-grid].
o Define a standard interface and API for interacting with the
repository. Requirements to consider include: creating a secure
channel between a publisher and the repository, creating a secure
channel between a subscriber and the repository, and the types of
interactions that must be supported between publishers and
subscribers to a repository.
o Define a standard interface for communications between the posture
broker client and posture transport client(s) as well as the
posture broker server and posture transport server(s).
o Retention of posture information on the target endpoint.
o Define an orchestrator component as well as publish/subscribe
interface for it.
o Define an evaluator component as well as an interface for it.
o Reassess the use of MAC addresses, including market research to
determine if MAC addresses continue to be a widely implemented
device identifier among network tools.
7. Acknowledgements
The authors wish to thank all of those in the TCG TNC work group who
contributed to development of the TNC ECP specification upon which
this document is based.
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+-----------------------+-------------------------------------------+
| Member | Organization |
+-----------------------+-------------------------------------------+
| Padma Krishnaswamy | Battelle Memorial Institute |
| | |
| Eric Fleischman | Boeing |
| | |
| Richard Hill | Boeing |
| | |
| Steven Venema | Boeing |
| | |
| Nancy Cam-Winget | Cisco Systems |
| | |
| Scott Pope | Cisco Systems |
| | |
| Max Pritikin | Cisco Systems |
| | |
| Allan Thompson | Cisco Systems |
| | |
| Nicolai Kuntze | Fraunhofer Institute for Secure |
| | Information Technology (SIT) |
| | |
| Ira McDonald | High North |
| | |
| Dr. Andreas Steffen | HSR University of Applied Sciences |
| | Rapperswil |
| | |
| Josef von Helden | Hochschule Hannover |
| | |
| James Tan | Infoblox |
| | |
| Steve Hanna (TNC-WG | Juniper Networks |
| Co-Chair) | |
| | |
| Cliff Kahn | Juniper Networks |
| | |
| Lisa Lorenzin | Juniper Networks |
| | |
| Atul Shah (TNC-WG Co- | Microsoft |
| Chair) | |
| | |
| Jon Baker | MITRE |
| | |
| Charles Schmidt | MITRE |
| | |
| Rainer Enders | NCP Engineering |
| | |
| Dick Wilkins | Phoenix Technologies |
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| | |
| David Waltermire | NIST |
| | |
| Mike Boyle | U.S. Government |
| | |
| Emily Doll | U.S. Government |
| | |
| Jessica Fitzgerald- | U.S. Government |
| McKay | |
| | |
| Mary Lessels | U.S. Government |
| | |
| Chris Salter | U.S. Government |
+-----------------------+-------------------------------------------+
Table 1: Members of the TNC Work Group that Contributed to the
Document
Special thanks also to Dan Ehrlich, Kathleen Moriarty, David Oliva
and Eric Voit for their thoughtful comments and edits.
8. IANA Considerations
This document does not define any new IANA registries. However, this
document does reference other documents that do define IANA
registries. As a result, the IANA Considerations section of the
referenced documents should be consulted.
9. Security Considerations
This Security Considerations section includes an analysis of the
attacks that may be mounted against systems that implement the EPCP
(Section 9.1) and the countermeasures that may be used to prevent or
mitigate these attacks (Section 9.2). Overall, a substantial
reduction in cyber risk can be achieved.
9.1. Threat Model
This section lists the attacks that can be mounted on a NEA
implementation of an EPCP environment. The following section
(Section 9.2) describes countermeasures.
Because the EPCP describes a specific use case for NEA components,
many security considerations for these components are addressed in
more detail in the technical specifications: [RFC8412], [IF-IMC],
[RFC5793], [Server-Discovery], [RFC6876], [IF-IMV].
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9.1.1. Endpoint Attacks
While the EPCP provides substantial improvements in endpoint
security, endpoints can still be compromised. For this reason, all
parties must regard data coming from endpoints as potentially
unreliable or even malicious. An analogy can be drawn with human
testimony in an investigation or trial. Human testimony is essential
but must be regarded with suspicion.
o Compromise of endpoint: A compromised endpoint may report false
information to confuse or even provide maliciously crafted
information with a goal of infecting others.
o Putting bad information in SWID directory: Even if an endpoint is
not completely compromised, some of the software running on it may
be unreliable or even malicious. This software, potentially
including the SWID generation or discovery tool, or malicious
software pretending to be a SWID generation or discovery tool, can
place incorrect or maliciously crafted information into the SWID
directory. Endpoint users may even place such information in the
directory, whether motivated by curiosity or confusion or a desire
to bypass restrictions on their use of the endpoint.
o Identity spoofing (impersonation): A compromised endpoint may
attempt to impersonate another endpoint to gain its privileges or
to besmirch the reputation of that other endpoint. This is of
particular concern when using MAC addresses to identify endpoints,
which, while widely used in endpoint behavior monitoring and
threat assessment tools, are easy to spoof.
9.1.2. Network Attacks
Generally, the network cannot be trusted. A variety of attacks can
be mounted using the network, including:
o Eavesdropping, modification, injection, replay, deletion;
o Traffic analysis; and
o Denial of service and blocking traffic.
9.1.3. Posture Manager Attacks
The posture manager is a critical security element and therefore
merits considerable scrutiny. A variety of attacks can be leveraged
against the Posture Manager.
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o Compromised trusted manager: A compromised posture manager or a
malicious party that is able to impersonate a posture manager can
incorrectly grant or deny access to endpoints, place incorrect
information into the repository, or send malicious messages to
endpoints.
o Misconfiguration of posture manager: Accidental or purposeful
misconfiguration of a trusted posture manager can cause effects
that are similar to those listed for compromised trusted posture
manager.
o Malicious untrusted posture manager: An untrusted posture manager
cannot mount any significant attacks because all properly
implemented endpoints will refuse to engage in any meaningful
dialog with such a posture manager.
9.1.4. Repository Attacks
The repository is also an important security element and therefore
merits careful scrutiny.
o Putting bad information into trusted repository: An authorized
repository client such as a server may be able to put incorrect
information into a trusted repository or delete or modify
historical information, causing incorrect decisions about endpoint
security. Placing maliciously crafted data in the repository
could even lead to compromise of repository clients, if they fail
to carefully check such data.
o Compromised trusted repository: A compromised trusted repository
or a malicious untrusted repository that is able to impersonate a
trusted repository can lead to effects similar to those listed for
"Putting bad information into trusted repository". Further, a
compromised trusted repository can report different results to
different repository clients or deny access to the repository for
selected repository clients.
o Misconfiguration of trusted repository: Accidental or purposeful
misconfiguration of a trusted repository can deny access to the
repository or result in loss of historical data.
o Malicious untrusted repository: An untrusted repository cannot
mount any significant attacks because all properly implemented
repository clients will refuse to engage in any meaningful dialog
with such a repository.
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9.2. Countermeasures
This section lists the countermeasures that can be used in a NEA
implementation of an EPCP environment.
9.2.1. Countermeasures for Endpoint Attacks
This profile is in and of itself a countermeasure for a compromised
endpoint. A primary defense for an endpoint is to run up to date
software configured to be run as safely as possible.
Ensuring that anti-virus signatures are up to date and that a
firewall is configured are also protections for an endpoint that are
supported by the current NEA specifications.
For secure device identification and to correlate device identifiers
if the MAC address is randomized, MAC addresses should be collected
along with other, more secure endpoint identifiers. Endpoints that
have hardware cryptographic modules that are provisioned by the
enterprise, in accordance with [IEEE-802-1ar], can protect the
private keys used for authentication and help prevent adversaries
from stealing credentials that can be used for impersonation. Future
versions of the EPCP may want to discuss in greater detail how to use
a hardware cryptographic module, in accordance with [IEEE-802-1ar],
to protect credentials and to protect the integrity of the code that
executes during the bootstrap process by hashing or recording
indicators of compromise.
9.2.2. Countermeasures for Network Attacks
To address network attacks, [RFC6876] includes required encryption,
authentication, integrity protection, and replay protection.
[Server-Discovery] also includes authorization checks to ensure that
only authorized servers are trusted by endpoints. Any unspecified or
not yet specified network protocols employed in the EPCP (e.g. the
protocol used to interface with the repository) should include
similar protections.
These protections reduce the scope of the network threat to traffic
analysis and denial of service. Countermeasures for traffic analysis
(e.g. masking) are usually impractical but may be employed.
Countermeasures for denial of service (e.g. detecting and blocking
particular sources) SHOULD be used when appropriate to detect and
block denial of service attacks. These are routine practices in
network security.
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9.2.3. Countermeasures for Posture Manager Attacks
Because of the serious consequences of posture manager compromise,
posture managers SHOULD be especially well hardened against attack
and minimized to reduce their attack surface. They SHOULD be
monitored using the NEA protocols to ensure the integrity of the
behavior and analysis data stored on the posture manager and SHOULD
utilize an [IEEE-802-1ar]-compliant hardware cryptographic module for
identity and/or integrity measurements of the posture manager. They
should be well managed to minimize vulnerabilities in the underlying
platform and in systems upon which the posture manager depends.
Network security measures such as firewalls or intrusion detection
systems may be used to monitor and limit traffic to and from the
posture manager. Personnel with administrative access to the posture
manager should be carefully screened and monitored to detect problems
as soon as possible. Posture manager administrators should not use
password-based authentication but should instead use non-reusable
credentials and multi-factor authentication (where available).
Physical security measures should be employed to prevent physical
attacks on posture managers.
To ease detection of posture manager compromise, should it occur,
posture manager behavior should be monitored to detect unusual
behavior (such as a server reboot, unusual traffic patterns, or other
odd behavior). Endpoints should log and/or notify users and/or
administrators when peculiar posture manager behavior is detected.
To aid forensic investigation, permanent read-only audit logs of
security-relevant information pertaining to posture manager
(especially administrative actions) should be maintained. If posture
manager compromise is detected, the posture manager's certificate
should be revoked and careful analysis should be performed of the
source and impact of this compromise. Any reusable credentials that
may have been compromised should be reissued.
Endpoints can reduce the threat of server compromise by minimizing
the number of trusted posture managers, using the mechanisms
described in [Server-Discovery].
9.2.4. Countermeasures for Repository Attacks
If the host for the repository is located on its own endpoint, it
should be protected with the same measures taken to protect the
posture manager. In this circumstance, all messages between the
posture manager and repository should be protected with a mature
security protocol such as TLS or IPsec.
The repository can aid in the detection of compromised endpoints if
an adversary cannot tamper with its contents. For instance, if an
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endpoint reports that it does not have an application with a known
vulnerability installed, an administrator can check whether the
endpoint might be lying by querying the repository for the history of
what applications were installed on the endpoint.
To help prevent tampering with the information in the repository:
1. Only authorized parties should have privilege to run code on the
endpoint and to change the repository.
2. If a separate endpoint hosts the repository, then the
functionality of that endpoint should be limited to hosting the
repository. The firewall on the repository should only allow
access to the posture manager and to any endpoint authorized for
administration.
3. The repository should ideally use "write once" media to archive
the history of what was placed in the repository, to include a
snapshot of the current status of applications on endpoints.
10. Privacy Considerations
The EPCP specifically addresses the collection of posture data from
enterprise endpoints by an enterprise network. As such, privacy is
not going to often arise as a concern for those deploying this
solution.
A possible exception may be the concerns a user may have when
attempting to connect a personal endpoint (such as a phone or mobile
endpoint) to an enterprise network. The user may not want to share
certain details, such as an endpoint identifier or SWID tags, with
the enterprise. The user can configure their NEA client to reject
requests for this information; however, it is possible that the
enterprise policy will not allow the user's endpoint to connect to
the network without providing the requested data.
An enterprise network should limit access to endpoint posture and
identification information to authorized users.
11. References
11.1. Informative References
[CIS] http://www.cisecurity.org/controls/, "CIS Critical
Security Controls".
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[DSD] http://www.dsd.gov.au/publications/csocprotect/
top_4_mitigations.htm, "Top 4 Mitigation Strategies to
Protect Your ICT System", November 2012.
[ECP] Trusted Computing Group, "TCG Trusted Network Connect
Endpoint Compliance Profile, Version 1.10", December 2014.
[IEEE-802-1ar]
Institute of Electrical and Electronics Engineers, "IEEE
802.1ar", December 2009.
[RFC5209] Sangster, P., Khosravi, H., Mani, M., Narayan, K., and J.
Tardo, "Network Endpoint Assessment (NEA): Overview and
Requirements", RFC 5209, DOI 10.17487/RFC5209, June 2008,
<https://www.rfc-editor.org/info/rfc5209>.
[TNC] Trusted Computing Group, "TCG Trusted Network Connect TNC
Architecture for Interoperability, Version 1.5", February
2012.
11.2. Normative References
[I-D.ietf-mile-xmpp-grid]
Cam-Winget, N., Appala, S., Pope, S., and P. Saint-Andre,
"Using XMPP for Security Information Exchange", draft-
ietf-mile-xmpp-grid-04 (work in progress), October 2017.
[I-D.ietf-netconf-restconf-notif]
Voit, E., Rahman, R., Nilsen-Nygaard, E., Clemm, A., and
A. Bierman, "Dynamic subscription to YANG Events and
Datastores over RESTCONF", draft-ietf-netconf-restconf-
notif-15 (work in progress), June 2019.
[I-D.ietf-netconf-subscribed-notifications]
Voit, E., Clemm, A., Prieto, A., Nilsen-Nygaard, E., and
A. Tripathy, "Customized Subscriptions to a Publisher's
Event Streams", draft-ietf-netconf-subscribed-
notifications-13 (work in progress), June 2018.
[I-D.ietf-netconf-yang-push]
Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen-
Nygaard, E., Bierman, A., and B. Lengyel, "YANG Datastore
Subscription", draft-ietf-netconf-yang-push-12 (work in
progress), December 2017.
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[I-D.ietf-sacm-terminology]
Waltermire, D., Montville, A., Harrington, D., and N. Cam-
Winget, "Terminology for Security Assessment", draft-ietf-
sacm-terminology-05 (work in progress), August 2014.
[IF-IMC] Trusted Computing Group, "TCG Trusted Network Connect TNC
IF-IMC, Version 1.3", February 2013.
[IF-IMV] Trusted Computing Group, "TCG Trusted Network Connect TNC
IF-IMV, Version 1.4", December 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5792] Sangster, P. and K. Narayan, "PA-TNC: A Posture Attribute
(PA) Protocol Compatible with Trusted Network Connect
(TNC)", RFC 5792, DOI 10.17487/RFC5792, March 2010,
<https://www.rfc-editor.org/info/rfc5792>.
[RFC5793] Sahita, R., Hanna, S., Hurst, R., and K. Narayan, "PB-TNC:
A Posture Broker (PB) Protocol Compatible with Trusted
Network Connect (TNC)", RFC 5793, DOI 10.17487/RFC5793,
March 2010, <https://www.rfc-editor.org/info/rfc5793>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/info/rfc6242>.
[RFC6876] Sangster, P., Cam-Winget, N., and J. Salowey, "A Posture
Transport Protocol over TLS (PT-TLS)", RFC 6876,
DOI 10.17487/RFC6876, February 2013,
<https://www.rfc-editor.org/info/rfc6876>.
[RFC7317] Bierman, A. and M. Bjorklund, "A YANG Data Model for
System Management", RFC 7317, DOI 10.17487/RFC7317, August
2014, <https://www.rfc-editor.org/info/rfc7317>.
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[RFC7589] Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the
NETCONF Protocol over Transport Layer Security (TLS) with
Mutual X.509 Authentication", RFC 7589,
DOI 10.17487/RFC7589, June 2015,
<https://www.rfc-editor.org/info/rfc7589>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8412] Schmidt, C., Haynes, D., Coffin, C., Waltermire, D., and
J. Fitzgerald-McKay, "Software Inventory Message and
Attributes (SWIMA) for PA-TNC", RFC 8412,
DOI 10.17487/RFC8412, July 2018,
<https://www.rfc-editor.org/info/rfc8412>.
[Server-Discovery]
Trusted Computing Group, "DRAFT: TCG Trusted Network
Connect PDP Discovery and Validation, Version 1.0",
October 2015.
[SWID] "Information technology--Software asset management--Part
2: Software identification tag", ISO/IEC 9899:1999, 2009.
Appendix A. Rationale for an EPCP Solution
A.1. Preventative Posture Assessments
The value of continuous endpoint posture assessment is well
established. Security experts have identified asset management and
vulnerability remediation as a critical step for preventing
intrusions. Application whitelisting, patching applications and
operating systems, and using the latest versions of applications top
the Defense Signals Directorate's "Top 4 Mitigations to Protect Your
ICT System". [DSD] "Inventory of Authorized and Unauthorized
Endpoints", "Inventory of Authorized and Unauthorized Software", and
"Continuous Vulnerability Assessment and Remediation" are Controls 1,
2, and 3, respectively, of the CIS Controls [CIS]. While there are
commercially available solutions that attempt to address these
security controls, these solutions do not run on all types of
endpoints; consistently interoperate with other tools that could make
use of the data collected; collect posture information from all types
of endpoints in a consistent, standardized schema; or require vetted,
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standardized protocols that have been evaluated by the international
community for cryptographic soundness.
As is true of most solutions offered today, the solution found in the
EPCP does not attempt to solve the lying endpoint problem, or detect
infected endpoints; rather, it focuses on ensuring that healthy
endpoints remain healthy by keeping software up-to-date and patched.
A.2. All Network-Connected Endpoints are Endpoints
As defined by [I-D.ietf-sacm-terminology], an endpoint is any
physical or virtual computing endpoint that can be connected to a
network. Posture assessment against policy is equally, if not more,
important for continuously connected endpoints, such as enterprise
workstations and infrastructure endpoints, as it is for sporadically
connected endpoints. Continuously connected endpoints are just as
likely to fall out of compliance with policy, and a standardized
posture assessment method is necessary to ensure they can be properly
handled.
A.3. All Endpoints on the Network Must be Uniquely Identified
Many administrators struggle to identify what endpoints are connected
to the network at any given time. By requiring a standardized method
of endpoint identity, the EPCP will enable administrators to answer
the basic question, "What is on my network?" In
[I-D.ietf-sacm-terminology], SACM defines this set of endpoints on
the network as the SACM domain. Unique endpoint identification also
enables the comparison of current and past endpoint posture
assessments, by allowing administrators to correlate assessments from
the same endpoint. This makes it easier to flag suspicious changes
in endpoint posture for manual or automatic review, and helps to
swiftly identify malicious changes to endpoint applications.
A.4. Standardized Data Models
Meeting EPCP best practices requires the use of standardized data
models for the exchange of posture information. This helps to ensure
that the posture information sent from endpoints to the repository
can be easily stored, due to their known format, and shared with
authorized endpoints and users.
Posture information must be sent over standardized protocols to
ensure the confidentiality and authenticity of this data while in
transit. Implementations of the EPCP include [RFC6876] and [RFC6241]
for communication between the target endpoint and the posture
manager. These protocols allow networks that implement this solution
to collect large amounts of posture information from an endpoint to
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make decisions about that endpoint's compliance with some policy.
The EPCP offers a solution for all endpoints already connected to the
network. Periodic assessments and automated reporting of changes to
endpoint posture allow for instantaneous identification of connected
endpoints that are no longer compliant to some policy.
A.5. Posture Information Must Be Stored
Posture information must be stored by the repository and must be
exposed to an interface at the posture manager. Standard data models
enable standard queries from an interface exposed to an administrator
at the posture manager console. A repository must retain any current
posture information retrieved from the target endpoint and store it
indexed by the unique identifier for the endpoint. Any posture
collection manager specified by this profile must be able to
ascertain from its corresponding posture collection engine whether
the posture information is up to date. An interface on the posture
manager must support a request to obtain up-to-date information when
an endpoint is connected. This interface must also support the
ability to make a standard set of queries about the posture
information stored by the repository. In the future, some forms of
posture information might be retained at the endpoint. The interface
on the posture manager must accommodate the ability to make a request
to the corresponding posture collection engine about the posture of
the target endpoint. Standard data models and protocols also enable
the security of posture assessment results. By storing these results
indexed under the endpoint's unique identification, secure storage
itself enables endpoint posture information correlation, and ensures
that the enterprise's repositories always offer the freshest, most
up-to-date view of the enterprise's endpoint posture information
possible.
A.6. Posture Information Can Be Shared
By exposing posture information using a standard interface and API,
other security and operational components have a high level of
insight into the enterprise's endpoints and the software installed on
them. This will support innovation in the areas of asset management,
vulnerability scanning, and administrative interfaces, as any
authorized infrastructure endpoint can interact with the posture
information.
A.7. Enterprise Asset Posture Information Belongs to the Enterprise
Owners and administrators must have complete control of posture
information, policy, and endpoint mitigation. Standardized data
models, protocols and interfaces help to ensure that this posture
information is not locked in proprietary databases, but is made
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available to its owners. This enables administrators to develop as
nuanced a policy as necessary to keep their networks secure. Of
course, there may be exceptions to this such as the case with
privacy-related information (e.g., personally identifiable
information).
Appendix B. EPCP Supported Use Cases and Non-Supported Use Cases
B.1. Supported Use Cases
The following sections describe the different use cases supported by
the EPCP.
B.1.1. Hardware Asset Management
Using the administrative interface on the posture manager, an
authorized user can learn:
o what endpoints are connected to the network at any given time; and
o what SWID tags were reported for the endpoints.
The ability to answer these questions offers a standards-based
approach to asset management, which is a vital part of enterprise
processes such as compliance report generation for the Federal
Information Security Modernization Act (FISMA), Payment Card Industry
Data Security Standard (PCI DSS), Health Insurance Portability and
Accountability Act (HIPAA), etc.
B.1.2. Software Asset Management
The administrative interface on the posture manager provides the
ability for authorized users and infrastructure to know which
software is installed on which endpoints on the enterprise's network.
This allows the enterprise to answer questions about what software is
installed to determine if it is licensed or prohibited. This
information can also drive other use cases such as:
o vulnerability management: knowing what software is installed
supports the ability to determine which endpoints contain
vulnerable software and need to be patched.
o configuration management: knowing which security controls need to
be applied to harden installed software and better protect
endpoints.
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B.1.3. Vulnerability Management
The administrative interface also provides the ability for authorized
users or infrastructure to locate endpoints running software for
which vulnerabilities have been announced. Because of
1. the unique IDs assigned to each endpoint; and
2. the rich application data provided in the endpoints' posture
information,
the repository can be queried to find all endpoints running a
vulnerable application. Endpoints suspected of being vulnerable can
be addressed by the administrator or flagged for further scrutiny.
B.1.4. Threat Detection and Analysis
The repository's standardized API allows authorized infrastructure
endpoints and software to search endpoint posture assessment
information for evidence that an endpoint's software inventory has
changed, and can make endpoint software inventory data available to
other endpoints. This automates security data sharing in a way that
expedites the correlation of relevant network data, allowing
administrators and infrastructure endpoints to identify odd endpoint
behavior and configuration using secure, standards-based data models
and protocols.
B.2. Non-Supported Use Cases
Several use cases, including but not limited to these, are not
covered by the EPCP:
o Gathering non-standardized types of posture information: The EPCP
does not prevent administrators from collecting posture
information in proprietary formats from the endpoint; however it
does not set requirements for doing so.
o Solving the lying endpoint problem: The EPCP does not address the
lying endpoint problem; the Profile makes no assertions that it
can catch an endpoint that is, either maliciously or accidentally,
reporting false posture information to the posture manager.
However, other solutions may be able to use the posture
information collected using the capabilities described in this
profile to catch an endpoint in a lie. For example, a sensor may
be able to compare the posture information it has collected on an
endpoint's activity on the network to what the endpoint reported
to the server and flag discrepancies. However, these capabilities
are not described in this profile.
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Appendix C. Endpoint Posture Collection Profile Examples
The following subsections provide examples of the EPCP as implemented
using components from the NEA architecture.
C.1. Continuous Posture Assessment of an Endpoint
Endpoint Posture Manager
+---------------+ +---------------+
| | | |
| +-----------+ | | +-----------+ |
| | SWID | | | | SWID | |
| | Posture | | | | Posture | |
| | Collector | | | | Validator | |
| +-----------+ | | +-----------+ |
| | | | | |
| | IF-IMC | | | IF-IMV |
| | | | | |
| +-----------+ | | +-----------+ |
| | PB Client | | | | PB Server | |
| +-----------+ | | +-----------+ |
| | | | | |
| | | | | |
| | | | | |
| +-----------+ | | +-----------+ |
| | PT Client | |<------>| | PT Server | |
| +-----------+ | PT-TLS | +-----------+ |
| | | |
+---------------+ +---------------+
Figure 4: Continuous Posture Assessment of an Endpoint
C.1.1. Change on Endpoint Triggers Posture Assessment
A new application is installed on the endpoint, and the SWID
directory is updated. This triggers an update from the SWID posture
collector to the SWID posture validator. The message is sent down
the NEA stack, encapsulated by NEA protocols until it is sent by the
posture transport client to the posture transport server. The
posture transport server then forwards it up through the stack, where
the layers of encapsulation are removed until the SWID Message
arrives at the SWID posture validator.
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Endpoint Posture Manager
+---------------+ +---------------+
| | | |
| +-----------+ | | +-----------+ |
| | SWID | | | | SWID | |
| | Posture | | | | Posture | |
| | Collector | | | | Validator | |
| +-----------+ | | +-----------+ |
| | | SWID Message | | |
| | IF-IMC | for PA-TNC | | IF-IMV |
| | | | | |
| +-----------+ | | +-----------+ |
| | PB Client | | | | PB Server | |
| +-----------+ | | +-----------+ |
| | | | | |
| | | PB-TNC {SWID | | |
| | | Message for | | |
| | | PA-TNC} | | |
| +-----------+ | | +-----------+ |
| | PT Client | |<-------------->| | PT Server | |
| +-----------+ | PT-TLS {PB-TNC | +-----------+ |
| | {SWID Message | |
+---------------+ for PA-TNC}} +---------------+
Figure 5: Compliance Protocol Encapsulation
The SWID posture validator stores the new tag information in the
repository. If the tag indicates that the endpoint is compliant to
the policy, then the process is complete until the next time an
update is needed (either because policy states that the endpoint must
submit posture assessment results periodically or because an
install/uninstall/update on the endpoint triggers a posture
assessment).
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Endpoint Posture Manager
+---------------+ +---------------+
| | | |
| +-----------+ | | +-----------+ |
| | SWID | | | | SWID |-|-+
| | Posture | | | | Posture | | |
| | Collector | | | | Validator | | |
| +-----------+ | | +-----------+ | |
| | | | | | | Repository
| | IF-IMC | | | IF-IMV | | +--------+
| | | | | | | | |
| +-----------+ | | +-----------+ | | | |
| | PB Client | | | | PB Server | | +---->| |
| +-----------+ | | +-----------+ | | |
| | | | | | +--------+
| | | | | |
| | | | | |
| +-----------+ | | +-----------+ |
| | PT Client | |<------>| | PT Server | |
| +-----------+ | PT-TLS | +-----------+ |
| | | |
+---------------+ +---------------+
Figure 6: Storing SWIDs in the Repository
If the endpoint has fallen out of compliance with a policy, the
posture manager can alert the administrator via the posture manager's
administrative interface. The administrator can then take steps to
address the problem. If the administrator has already established a
policy for automatically addressing this problem, that policy will be
followed.
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(")
__|__
+-->|
Endpoint Posture Manager | / \
+---------------+ +---------------+ |
| | | | |
| +-----------+ | | +-----------+ | |
| | SWID | | | | SWID |-|-+
| | Posture | | | | Posture | |
| | Collector | | | | Validator | |
| +-----------+ | | +-----------+ |
| | | | | | Repository
| | IF-IMC | | | IF-IMV | +--------+
| | | | | | | |
| +-----------+ | | +-----------+ | | |
| | PB Client | | | | PB Server | | | |
| +-----------+ | | +-----------+ | | |
| | | | | | +--------+
| | | | | |
| | | | | |
| +-----------+ | | +-----------+ |
| | PT Client | |<------>| | PT Server | |
| +-----------+ | PT-TLS | +-----------+ |
| | | |
+---------------+ +---------------+
Figure 7: Server Alerts Network Admin
C.2. Administrator Searches for Vulnerable Endpoints
An announcement is made that a particular version of a piece of
software has a vulnerability. The administrator uses the
administrative interface on the server to search the repository for
endpoints that reported the SWID tag for the vulnerable software.
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(")
__|__
+-->|
Endpoint Posture Manager | / \
+---------------+ +---------------+ |
| | | | |
| +-----------+ | | +-----------+ | |
| | SWID | | | | SWID |-|-+
| | Posture | | | | Posture | |
| | Collector | | | | Validator | |
| +-----------+ | | +-----------+ |
| | | | | | Repository
| | IF-IMC | | | IF-IMV | +--------+
| | | | | | | |
| +-----------+ | | +-----------+ | | |
| | PB Client | | | | PB Server | |------>| |
| +-----------+ | | +-----------+ | | |
| | | | | | +--------+
| | | | | |
| | | | | |
| +-----------+ | | +-----------+ |
| | PT Client | |<------>| | PT Server | |
| +-----------+ | PT-TLS | +-----------+ |
| | | |
+---------------+ +---------------+
Figure 8: Admin Searches for Vulnerable Endpoints
The repository returns a list of entries in the matching the
administrator's search. The administrator can then address the
vulnerable endpoints by taking some follow-up action such as removing
it from the network, quarantining it, or updating the vulnerable
software.
Appendix D. Change Log
D.1. -04 to -05
Updated the diagram so the Evaluator and Repository are "current
work".
Clarified how the Posture Collection Engine can push data, respond to
queries, and establish secure transport connectivity for fulfilling
subscriptions.
Expanded on the future work around leveraging NETCONF, RESTCONF, and
YANG Push for network devices.
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Documented the need to reassess MAC addresses as a device identifier.
Made various typographical and editorial changes.
D.2. -03 to -04
Addressed various comments from the SACM WG.
Refactored the document to better focus it on the communications
between endpoints and the posture manager and the best practices for
EPCP implementations.
Made other editorial changes and improved consistency throughout the
document.
D.3. -02 to -03
Addressed various comments from the SACM WG.
Added a reference to TCG ECP 1.0.
Removed text in the "SWID Posture Validator" section that states it
performs evaluation. This was removed because it contradicts the
posture manager not performing any evaluations.
Expanded the "Provisioning" section of the "EPCP Transactions"
section to include examples of endpoint identifiers and the need to
provision endpoints with components and data models.
Combined text for the capabilities of the Administrative Interface
and API.
Removed superfluous and introductory text from the "Security
Considerations" section.
Renamed section "Vulnerability Searches" to Vulnerability
Management".
Changed I-D category to BCP.
Changed references to the NETMOD architecture to the NETCONF
architecture because NETCONF represents the management protocol
whereas NETMOD is focused on the definition of data models.
Addressed various editorial suggestions.
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D.4. -01 to -02
Addressed various comments from the SACM WG.
Added a section for the collection of posture information from
network devices using standards from the NETMOD WG.
Updated EPCP component diagrams so they were not specific to a NEA-
based implementation.
Updated EPCP NEA example diagrams to reflect all the components in
the NEA architecture.
D.5. -00 to -01
There are no textual changes associated with this revision. This
revision simply reflects a resubmission of the document so that it
remains in active status.
D.6. -01 to -02
Added references to the Software Inventory Message and Attributes
(SWIMA) for PA-TNC I-D.
Replaced references to PC-TNC with IF-IMC.
Removed erroneous hyphens from a couple of section titles.
Made a few minor editorial changes.
D.7. -02 to -00
Draft adopted by IETF SACM WG.
D.8. -00 to -01
Significant edits to up-level the draft to describe SACM collection
over multiple different protocols.
Replaced references to SANS with CIS.
Made other minor editorial changes.
Authors' Addresses
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Danny Haynes
The MITRE Corporation
202 Burlington Road
Bedford, MA 01730
USA
Email: dhaynes@mitre.org
Jessica Fitzgerald-McKay
Department of Defense
9800 Savage Road
Ft. Meade, Maryland
USA
Email: jmfitz2@nsa.gov
Lisa Lorenzin
Pulse Secure
2700 Zanker Rd., Suite 200
San Jose, CA 95134
US
Email: llorenzin@pulsesecure.net
