Internet DRAFT - draft-ietf-sacm-requirements
draft-ietf-sacm-requirements
SACM N. Cam-Winget
Internet-Draft Cisco Systems
Intended status: Informational L. Lorenzin
Expires: February 2, 2018 Pulse Secure
August 1, 2017
Security Automation and Continuous Monitoring (SACM) Requirements
draft-ietf-sacm-requirements-18
Abstract
This document defines the scope and set of requirements for the
Secure Automation and Continuous Monitoring (SACM) architecture, data
model and transfer protocols. The requirements and scope are based
on the agreed upon use cases ([RFC7632]).
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 2, 2018.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirements for SACM . . . . . . . . . . . . . . . . . . 4
2.2. Requirements for the Architecture . . . . . . . . . . . . 7
2.3. Requirements for the Information Model . . . . . . . . . 9
2.4. Requirements for the Data Model . . . . . . . . . . . . . 10
2.5. Requirements for Data Model Operations . . . . . . . . . 12
2.6. Requirements for SACM Transfer Protocols . . . . . . . . 14
3. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
5. Security Considerations . . . . . . . . . . . . . . . . . . . 15
5.1. Trust between Provider and Requestor . . . . . . . . . . 16
5.2. Privacy Considerations . . . . . . . . . . . . . . . . . 17
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.1. Normative References . . . . . . . . . . . . . . . . . . 18
6.2. Informative References . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction
Today's environment of rapidly-evolving security threats highlights
the need to automate the sharing of security information (such as
posture information) while protecting user information and the
systems that store, process, and transmit this information. Security
threats can be detected in a number of ways. The Secure Automation
and Continuous Monitoring (SACM) charter focuses on how to collect
and share this information based on use cases that involve posture
assessment of endpoints.
Scalable and sustainable collection, expression, and evaluation of
endpoint information is foundational to SACM's objectives. To secure
and defend a 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 document focuses on describing the requirements for facilitating
the exchange of posture assessment information in the enterprise, in
particular, for the use cases as exemplified in [RFC7632]. As
proposals are evaluated for SACM standardization, their drafts are
expected to include a section that describe how they address each of
the enumerated requirements.
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Also, this document uses terminology defined in
[I-D.ietf-sacm-terminology].
1.1. Requirements Language
Use of each capitalized word within a sentence or phrase carries the
following meaning during the SACM WG's protocol selection process:
MUST - indicates an absolute requirement
MUST NOT - indicates something absolutely prohibited
SHOULD - indicates a strong recommendation of a desired result
SHOULD NOT - indicates a strong recommendation against a result
MAY - indicates a willingness to allow an optional outcome
When the words appear in lower case, their natural language meaning
is used.
2. Requirements
This document defines requirements based on the SACM use cases
described in [RFC7632]. This section describes the requirements used
by SACM to assess and compare candidate data models, interfaces, and
protocols. These requirements express characteristics or features
that a candidate protocol, information model, or data model must be
capable of offering to ensure security and interoperability.
Multiple data models, protocols, and transfers may be employed in a
SACM environment. A SACM transfer protocol is one that runs on top
of transport layer protocols such as TCP/IP or internet layer
protocols such as HTTP, carries operations (requests / responses),
and moves data.
SACM will define an architecture and information model focused on
addressing the needs for determining, sharing, and using posture
information via Posture Information Providers and Posture Information
Consumers securely. With the information model defining assets and
attributes to facilitate the guidance, collection, and assessment of
posture, tasks that should be considered include:
1. Asset Classification: Map the target endpoint and/or the assets
on the target endpoints to asset classes. This enables
identification of the attributes needed to exchange information
pertaining to the target endpoint.
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2. Attribute Definition: Define the attributes desired to be
collected from each target endpoint. For instance, organizations
will want to know what software is installed and its critical
security attributes such as patch level.
3. Policy Definition: This is where an organization can express its
policy for acceptable or problematic values of an endpoint
attribute. The expected values of an endpoint attribute are
determined for later comparison against the actual endpoint
attribute values during the evaluation process. Expected values
may include both those values which are good as well as those
values which represent problems, such as vulnerabilities. The
organization can also specify the endpoint attributes that are to
be present for a given target endpoint.
4. Information Collection: Collect information (attribute values)
from the target endpoint to populate the endpoint data.
5. Endpoint Assessment: Evaluate the actual values of the endpoint
attributes against those expressed in the policy. (An evaluation
result may become additional endpoint data).
6. Result Reporting: Report the results of the evaluation for use by
other components. Examples of use of a report would be
additional evaluation, network enforcement, vulnerability
detection, and license management.
2.1. Requirements for SACM
Many deployment scenarios can be instantiated to address the above
tasks and use cases defined in [RFC7632]. To ensure
interoperability, scalability, and flexibility in any of these
deployments, the following requirements are defined for proposed SACM
standards:
G-001 Solution Extensibility: The information model, data models,
protocols, and transfers defined by SACM MUST be designed to allow
support for future (SACM) extensions. SACM MUST allow for both
standardized and proprietary extensions.
1. The information model and programmatic interfaces (see G-012 for
one example) MUST support the ability to add new operations
while maintaining backwards compatibility. SACM-defined
transfer protocols MUST have extensibility to allow them to
transfer operations that are defined in the future.
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2. The query language MUST allow for general inquiries, as well as
expression of specific attributes or relationships between
attributes; the retrieval of specific information based on an
event, or on a continuous basis; and the ability to retrieve
specific pieces of information, specific types or classes of
information, or the entirety of available information.
3. The information model MUST accommodate the interoperable
addition of new data types and/or schemas.
G-002 Interoperability: The data models, protocols, and transpors
MUST be specified with enough details to ensure interoperability.
G-003 Scalability: SACM needs to support a broad set of deployment
scenarios. The data models, protocols, and transports has to be
scalable unless they are specifically defined to apply to a special-
purpose scenario, such as constrained devices. A SACM transfer
protocol standard SHOULD include a section on scalability
considerations that addresses the number of endpoints and amount of
information to which it can reasonably be expected to scale.
Scalability must be addressed to support:
* Large message: It is possible that the size of posture assessment
information can vary from a single assessment that is small in
size to a very large message or a very large set of assessments
(up to multiple gigabytes in size).
* Large number of messages per second: A deployment may involve
many rapid or simultaneous events that require processing,
generating many messages per second.
* Large number of providers and consumers: A deployment may consist
of a very large number of endpoints requesting and/or producing
posture assessment information.
* Large number of target endpoints: A deployment may be managing
information of a very large number of target endpoints.
G-004 Versatility: The data model, protocols, and transports must be
suitably specified to enable implementations to fit into different
deployment models and scenarios, including considerations for
implementations of data models and transports operating in
constrained environments. Separate solutions may be necessary to
meet the needs of specific deployment models and scenarios.
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G-005 Information Extensibility: Non-standard (implementation-
specific) attributes MUST be supported. A method SHOULD be defined
for preventing collisions from occurring in the naming of all
attributes independent of their source. For interoperability and
scope boundary, the information model MUST define the mandatory set
of attributes.
G-006 Data Protection: To protect the information being shared, SACM
components MUST protect the integrity and confidentiality of data in
transit (end to end) and data at rest (as information is stored in
repositories). Mechanisms for this protection are unspecified but
should include industry best practices. These mechanisms are
required to be available (i.e. all data-handling components must
support them), but are not required to be used in all cases.
G-007 Data Partitioning: A method for partitioning data MUST be
supported to accommodate considerations such as geographic,
regulatory, operational requirements, overlay boundaries, and
federation (where the data may be collected in multiple locations
and either centralized or kept in the local region). Where
replication of data is supported, it is required that methods exist
to prevent update loops.
G-008 Versioning and Backward Compatibility: Announcement and
negotiation of versions, inclusive of existing capabilities (such as
transfer protocols, data models, specific attributes within data
models, standard attribute expression sets, etc.) MUST be
supported. Negotiation for both versioning and capabilities is
needed to accommodate future growth and ecosystems with mixed
capabilities.
G-009 Information Discovery: There MUST be mechanisms for components
to discover what information is available across the ecosystem (i.e.
a method for cataloging data available in the ecosystem and
advertising it to consumers), where to go to get a specific piece of
that information (i.e. which provider has the information), and what
schemas are in use for organizing the information. For example,
providing a method by which a node can locate the advertised
information so that consumers are not required to have a priori
knowledge to find available information.
G-010 Target Endpoint Discovery: SACM MUST define the means by which
target endpoints may be discovered. Use Case 2.1.2 describes the
need to discover endpoints and their composition.
G-011 Push and Pull Access: Three methods of data access MUST be
supported: a Pull model, a solicited Push model, and an unsolicited
Push models. All of the methods of data access MUST support the
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ability for the initiator to filter the set of posture assessment
information to be delivered. Additionally, the provider of the
information MUST be able to filter the set of posture assessment
information based on the permissions of the recipient. This
requirement is driven by use cases 2.1.3, 2.1.4 and 2.1.5.
G-012 SACM Component Interface: The interfaces by which SACM
components communicate to share endpoint posture information MUST be
well defined. That is, the interface defines the data model, SACM
transfer protocols, and network transfer protocols to enable SACM
components to communicate.
G-013 Endpoint Location and Network Topology: The SACM architecture
and interfaces MUST allow for the target endpoint (network) location
and network topology to be modeled and understood. Where
appropriate, the data model and the interfaces SHOULD allow for
discovery of the target endpoint location or network topology or
both.
G-014 Target Endpoint Identity: The SACM architecture and interfaces
MUST support the ability of components to provide attributes that
can be used to compose an identity for a target endpoint. These
identities MAY be composed of attributes from one or more SACM
components.
G-015 Data Access Control: Methods of access control must be
supported to accommodate considerations such as geographic,
regulatory, operational and federations. Entities accessing or
publishing data MUST identify themselves and pass access policy.
2.2. Requirements for the Architecture
Following are the requirements for the SACM architecture:
ARCH-001 Component functions: At the simplest abstraction, the SACM
architecture MUST represent the core components and interfaces
needed to perform the production and consumption of posture
assessment information.
ARCH-002 Scalability: The architectural components MUST account for
a range of deployments, from very small sets of endpoints to very
large deployments.
ARCH-003 Flexibility: The architectural components MUST account for
different deployment scenarios where the architectural components
may be implemented, deployed, or used within a single application,
service, or network, or may comprise a federated system.
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ARCH-004 Separation of Data and Management Functions: SACM MUST
define both the configuration and management of the SACM data models
and protocols used to transfer and share posture assessment
information.
ARCH-005 Topology Flexibility: Both centralized and decentralized
(peer-to-peer) information exchange MUST be supported. Centralized
data exchange enables use of a common data format to bridge together
data exchange between diverse systems, and can leverage a virtual
data store that centralizes and offloads all data access, storage,
and maintenance to a dedicated resource. Decentralized data
exchange enables simplicity of sharing data between relatively
uniform systems, and between small numbers of systems, especially
within a single enterprise domain. The fact that a centralized or
decentralized deployment is used SHOULD be invisible to a consumer.
However, there may be cases where the producer chooses to include
that information due to consumer preference
ARCH-006 Capability Negotiation: Announcement and negotiation of
functional capabilities (such as authentication protocols,
authorization schemes, data models, transfer protocols, etc.) MUST
be supported, enabling a SACM component to make inquiries about the
capabilities of other components in the SACM ecosystem.
ARCH-007 Role-based Authorization: The SACM architecture MUST be
capable of effecting role-based authorization. Distinction of
endpoints capable of and authorized to provide or consume
information is required to address appropriate access controls.
ARCH-008 Context-based Authorization: The SACM architecture MUST be
capable of effecting context-based authorization. Different
policies (e.g. business, regulatory, etc.) might specify what data
may be exposed to, or shared by, consumers based on one or more
attributes of the consumer. The policy might specify that consumers
are required to share specific information either back to the system
or to administrators.
ARCH-009 Time Synchronization: Actions or decisions based on time-
sensitive data (such as user logon/logoff, endpoint connection/
disconnection, endpoint behavior events, etc.) are all predicated on
a synchronized understanding of time. The SACM architecture MUST
provide a mechanism for all components to synchronize time. A
mechanism for detecting and reporting time discrepancies SHOULD be
provided by the architecture and reflected in the information model.
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2.3. Requirements for the Information Model
The SACM information model represents the abstracted representation
for Posture Assessment information to be communicated. SACM data
models must adhere to and comply with the SACM information model.
The requirements for the SACM information model include:
IM-001 Extensible Attribute Vocabulary: The information model MUST
define a minimum set of attributes for communicating Posture
Information, to ensure interoperability between data models.
(Individual data models may define attributes beyond the mandatory-
to-implement minimum set.) The attributes should be defined with a
clear mechanism for extensibility to enable data models to adhere to
SACM's required attributes as well as allow for their own
extensions. The attribute vocabulary should be defined with a clear
mechanism for extensibility to enable future versions of the
information model to be interoperably expanded with new attributes.
IM-002 Posture Data Publication: The information model MUST allow
for the data to be provided by a SACM component either solicited or
unsolicited. No aspect of the information model should be dependent
upon or assume a push or pull model of publication.
IM-003 Data Model Negotiation: SACM's information model MUST allow
support for different data models, data model versions, and
different versions of the operations on the data models and transfer
protocols. The SACM information model MUST include the ability to
discover and negotiate the use of a particular data model or any
data model.
IM-004 Data Model Identification: The information model MUST provide
a means to uniquely identify each data model. The identifier MUST
contain both an identifier of the data model and a version indicator
for the data model. The identifiers SHOULD be decomposable so that
a customer can query for any version of a specific data model and
compare returned values for older or newer than a desired version.
IM-005 Data Lifetime Management: The information model MUST provide
a means to allow data models to include data lifetime management.
The information model must identify attributes that can allow data
models to, at minimum, identify the data's origination time and
expected time of next update or data longevity (how long should the
data be assumed to still be valid).
IM-006 Singularity and Modularity: The SACM information model MUST
be singular (i.e. there is only one information model, not multiple
alternative information models from which to choose) and MAY be
modular (a conjunction of several sub-components) for ease of
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maintenance and extension. For example, endpoint identification
could be an independent sub-component of the information model, to
simplify updating of endpoint identification attributes.
2.4. Requirements for the Data Model
The SACM information model represents an abstraction for "what"
information can be communicated and "how" it is to be represented and
shared. It is expected that as applications may produce posture
assessment information, they may share it using a specific data
model. Similarly, applications consuming or requesting posture
assessment information, may require it be based on a specific data
model. Thus, while there may exist different data models and
schemas, they should adhere to the SACM information model and meet
the requirements defined in this section.
The specific requirements for candidate data models include:
DM-001 Element Association: A SACM Information Model consists of a
set of SACM Information Model elements. A SACM Data Model MUST be
derived from the SACM Information Model. A SACM Data Model consists
of a set of SACM Data Model elements. In this derivation, a SACM
Data Model element MAY map to one or more SACM Information Model
elements. In addition, a SACM Data Model MAY include additional
Data Model elements that are not associated with any SACM
Information Model elements.
DM-002 Data Model Structure: The data model can be structured either
as one single module or separated into modules and sub-modules that
allow for references between them. The data model structure MAY
reflect structure in the information model, but does not need to.
For example, the data model might use one module to define
endpoints, and that module might reference other modules that
describe the various assets associated with the endpoint.
Constraints and interfaces might further be defined to resolve or
tolerate ambiguity in the references (e.g. same IP address used in
two separate networks).
DM-003 Search Flexibility: The search interfaces and actions MUST
include the ability to start a search anywhere within a data model
structure, and the ability to search based on patterns ("wildcard
searches") as well as specific data elements.
DM-004 Full vs. Partial Updates: The data model SHOULD include the
ability to allow providers of data to provide the data as a whole,
or when updates occur. For example, a consumer can request a full
update on initial engagement, then request to receive deltas
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(updates containing only the changes since the last update) on an
ongoing basis as new data is generated.
DM-005 Loose Coupling: The data model SHOULD allow for a loose
coupling between the provider and the consumer, such that the
consumer can request information without being required to request
it from a specific provider, and a provider can publish information
without having a specific consumer targeted to receive it.
DM-006 Data Cardinality: The data model MUST describe their
constraints (e.g. cardinality). As posture information and the
tasks for collection, aggregation, or evaluation, could comprise one
or more attributes, interfaces and actions MUST allow and account
for such cardinality as well as whether the attributes are
conditional, optional, or mandatory.
DM-007 Data Model Negotiation: The interfaces and actions in the
data model MUST include capability negotiation to enable discovery
of supported and available data types and schemas.
DM-008 Data Origin: The data model MUST include the ability for
consumers to identify the data origin (provider that collected the
data).
DM-009 Origination Time: The data model SHOULD allow the provider to
include the information's origination time.
DM-010 Data Generation: The data model MUST allow the provider to
include attributes defining how the data was generated (e.g. self-
reported, reported by aggregator, scan result, etc.).
DM-011 Data Source: The data model MUST allow the provider to
include attributes identifying the data source (target endpoint from
which the data was collected) - e.g. hostname, domain (DNS) name or
application name.
DM-012 Data Updates: The data model SHOULD allow the provider to
include attributes defining whether the information provided is a
delta, partial, or full set of information.
DM-013 Multiple Collectors: The data model MUST support the
collection of attributes by a variety of collectors, including
internal collectors, external collectors with an authenticated
relationship with the endpoint, and external collectors based on
network and other observers.
DM-014 Attribute Extensibility: Use Cases in the whole of Section 2
describe the need for an attribute dictionary. With SACM's scope
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focused on posture assessment, the data model attribute collection
and aggregation MUST have a well-understood set of attributes
inclusive of their meaning or usage intent. The data model MUST
include all attributes defined in the information model and MAY
include additional attributes beyond those found in the information
model. Additional attributes MUST be defined in accordance with the
extensibility framework provided in the information model (see IM-
001).
DM-015 Solicited vs. Unsolicited Updates: The data model MUST enable
a provider to publish data either solicited (in response to a
request from a consumer) or unsolicited (as new data is generated,
without a request required). For example, an external collector can
publish data in response to a request by a consumer for information
about an endpoint, or can publish data as it observes new
information about an endpoint, without any specific consumer request
triggering the publication; a compliance-server provider may publish
endpoint posture information in response to a request from a
consumer (solicited), or it may publish posture information driven
by a change in the posture of the endpoint (unsolicited).
DM-016 tTransfer Agnostic: The data model MUST be transfer agnostic,
to allow for the data operations to leverage the most appropriate
SACM transfer protocol.
2.5. Requirements for Data Model Operations
Posture information data adhering to a data model must also provide
interfaces that include operations for access and production of the
data. Operations requirements are distinct from transfer
requirements in that operations requirements are requirements on the
application performing requests and responses, whereas transfer
requirements are requirements on the transfer protocol carrying the
requests / responses. The specific requirements for such operations
include:
OP-001 Time Synchronization: Request and response operations MUST be
timestamped, and published information SHOULD capture time of
publication. Actions or decisions based on time-sensitive data
(such as user logon/logoff, endpoint connection/disconnection,
endpoint behavior events, etc.) are all predicated on a synchronized
understanding of time. A method for detecting and reporting time
discrepancies SHOULD be provided.
OP-002 Collection Abstraction: Collection is the act of a SACM
component gathering data from a target endpoint. The request for a
data item MUST include enough information to properly identify the
item to collect, but the request shall not be a command to directly
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execute nor directly be applied as arguments to a command. The
purpose of this requirement is primarily to reduce the potential
attack vectors, but has the additional benefit of abstracting the
request for collection from the collection method, thereby allowing
more flexibility in how collection is implemented.
OP-003 Collection Composition: A collection request MAY be composed
of multiple collection requests (which yield collected values). The
desire for multiple values MUST be expressed as part of the
collection request, so that the aggregation can be resolved at the
point of collection without having to interact with the requestor.
This requirement should not be interpreted as preventing a collector
from providing attributes which were not part of the original
request.
OP-004 Attribute-based Query: A query operation is the act of
requesting data from a provider. Query operations SHOULD be based
on a set of attributes. Query operations MUST support both a query
for specific attributes and a query for all attributes. Use Case
2.1.2 describes the need for the data model to support a query
operation based on a set of attributes to facilitate collection of
information such as posture assessment, inventory (of endpoints or
endpoint components), and configuration checklist.
OP-005 Information-based Query with Filtering: The query operation
MUST support filtering. Use Case 2.1.3 describes the need for the
data model to support the means for the information to be collected
through a query mechanism. Furthermore, the query operation
requires filtering capabilities to allow for only a subset of
information to be retrieved. The query operation MAY be a
synchronous request or asynchronous request.
OP-006 Operation Scalability: The operation resulting from a query
operation MUST be able to handle the return and receipt of large
amounts of data. Use Cases 2.1.4 and 2.1.5 describe the need for
the data model to support scalability. For example, the query
operation may result in a very large set of attributes, as well as a
large set of targets.
OP-007 Data Abstraction: The data model MUST allow a SACM component
to communicate what data was used to construct the target endpoint's
identity, so other SACM components can determine whether they are
constructing an equivalent target endpoint (and its identity) and
whether they have confidence in that identity. SACM components
SHOULD have interfaces defined to transmit this data directly or to
refer to where the information can be retrieved.
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OP-008 Provider Restriction: Request operations MUST include the
ability to restrict the data to be provided by a specific provider
or a provider with specific characteristics. Response operations
MUST include the ability to identify the provider that supplied the
response. For example, a SACM Consumer should be able to request
that all of the data come from a specific provider by identity (e.g.
Provider A) or from a Provider that is in a specific location (e.g.
in the Boston office).
2.6. Requirements for SACM Transfer Protocols
The term SACM transfer protocol is intended to be distinguished from
underlying transport and internet layer protocols such as TCP/IP or
operating at an equivalent level as the HTTP. The SACM transfer
protocol is focused on moving data and performing necessary access
control operations; it is agnostic to the data model operations.
The requirements for SACM transfer protocols include:
T-001 Multiple transfer Protocol Support: SACM transfer protocols
will vary depending on the deployment model that relies on different
transfer layer requirements, different device capabilities, and
system configurations dealing with connectivity. For example, where
posture attributes may be collected directly from an endpoint using
NEA's model [RFC5209], different transports may be defined to
collect them using PT-EAP [RFC7171] or PT-TLS [RFC6876] depending on
the deployment scenario.
T-002 Data Integrity: SACM transfer protocols MUST be able to ensure
data integrity for data in transit.
T-003 Data Confidentiality: SACM transfer protocols MUST be able to
support data confidentiality. SACM transfer protocols MUST ensure
data protection for data in transit (e.g. by encryption) to provide
confidentiality, integrity, and robustness against protocol-based
attacks. Note that while the transfer MUST be able to support data
confidentiality, implementations MAY provide a configuration option
that enables and disables confidentiality in deployments.
Protection for data at rest is not in scope for transfer protocols.
Data protection MAY be used for both privacy and non-privacy
scenarios.
T-004 Transfer Protection: SACM transfer protocols MUST be capable
of supporting mutual authentication and replay protection.
T-005 Transfer Reliability: SACM transfer protocols MUST provide
reliable delivery of data. This includes the ability to perform
fragmentation and reassembly, and to detect replays. The SACM
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transfer may take advantage of reliability features in the network
transport; however, the network transport may be unreliable (e.g.
UDP), in which case the SACM transfer running over the unreliable
network transport is responsible for ensuring reliability (i.e. by
provisions such as confirmations and re-transmits).
T-006 Transfer Layer Requirements: Each SACM transfer protocol MUST
clearly specify the transport layer requirements it needs to operate
correctly. Examples of items that may need to be specified include
connectivity requirements, replay requirements, data link encryption
requirements, and/or channel binding requirements. These
requirements are needed in order for deployments to be done
correctly.
T-007 Transfer Protocol adoption: SACM SHOULD where reasonably
possible, leverage and use existing IETF transfer protocols versus
defining new ones.
3. Acknowledgments
The authors would like to thank Barbara Fraser, Jim Bieda, and Adam
Montville for reviewing and contributing to this draft. In addition,
we recognize valuable comments and suggestions made by Jim Schaad and
Chris Inacio.
4. IANA Considerations
This memo includes no request to IANA.
5. Security Considerations
This document defines the requirements for SACM. As such, it is
expected that several data models, protocols, and transfer protocols
may be defined or reused from already existing standards.
To address security and privacy considerations, the data model,
protocols, and transports must consider authorization based on
consumer function and privileges, to only allow authorized consumers
and providers to access specific information being requested or
published.
To enable federation across multiple entities (such as across
organizational or geographic boundaries) authorization must also
extend to infrastructure elements themselves, such as central
controllers / brokers / data repositories.
In addition, authorization needs to extend to specific information or
resources available in the environment. In other words,
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authorization is based on the subject (the information requestor),
the provider (the information responder), the object (the endpoint
the information is being requested on), and the attribute (what piece
of data is being requested). The method by which this authorization
is applied is unspecified.
SACM's charter focuses on the workflow orchestration and the sharing
of posture information for improving efficacy of security
applications such as compliance, configuration, assurance and other
threat and vulnerability reporting and remediation systems. While
the goal is to facilitate the flow of information securely, it is
important to note that participating endpoints may not be cooperative
or trustworthy.
5.1. Trust between Provider and Requestor
The information given from the provider to a requestor may come with
different levels of trustworthiness given the different potential
deployment scenarios and compromise either at the provider, the
requesting consumer, or devices that are involved in the transfer
between the provider and requestor. This section will describe the
different considerations that may reduce the level of trustworthiness
of the information provided.
In the information transfer flow, it is possible that some of the
devices may serve as proxies or brokers and as such, may be able to
observe the communications flowing between an information provider
and requestor. Without appropriate protections, it is possible for
these proxies and brokers to inject and affect man-in-the-middle
attacks.
It is common to, in general, distrust the network service provider,
unless the full hop by hop communications process flow is well
understood. As such, the posture information provider should protect
the posture information data it provides as well as the transfer it
uses. Similarly, while there may be providers whose goal is to
openly share its information, there may also be providers whose
policy is to grant access to certain posture information based on its
business or regulatory policy. In those situations, a provider may
require full authentication and authorization of the requestor (or
set of requestors) and share only the authorized information to the
authenticated and authorized requestors.
A requestor beyond distrusting the network service provider, must
also account that the information received from the provider may have
been communicated through an undetermined network communications
system. That is, the posture information may have traversed through
many devices before reaching the requestor. SACM specifications
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should provide the means for verifying data origin and data integrity
and at minimum, provide endpoint authentication and transfer
integrity.
A requestor may require data freshness indications, both knowledge of
data origination as well as time of publication so that it can make
more informed decisions about the relevance of the data based on its
currency and/or age.
It is also important to note that endpoint assessment reports,
especially as they may be provided by the target endpoint may pose
untrustworthy information. The considerations for this are described
in Section 8 of [RFC5209].
The trustworthiness of the posture information given by the provider
to one or many requestors is dependent on several considerations.
Some of these include the requestor requiring:
o Full disclosure of the network topology path to the provider(s).
o Direct (peer to peer) communication with the provider.
o Authentication and authorization of the provider.
o Either or both confidentiality and integrity at the transfer
layer.
o Either or both confidentiality and integrity at the data layer.
5.2. Privacy Considerations
SACM information may contain sensitive information about the target
endpoint as well as revealing identity information of the producer or
consumer of such information. Similarly, as part of the SACM
discovery mechanism, the advertised capabilities (and roles, e.g.
SACM components enabled) by the endpoint may be construed as private
information.
In addition to identity and SACM capabilities information disclosure,
the use of time stamps (or other attributes that can be used as
identifiers) could be further used to determine a target endpoint or
user's behavioral patterns. Such attributes may also be deemed
sensitive and may required further protection or obfuscation to meet
privacy concerns. That is, there may be applications as well as
business and regulatory practices that require that aspects of such
information be hidden from any parties that do not need to know it.
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Data confidentiality can provide some level of privacy but may fall
short where unnecessary data is still transmitted. In those cases,
filtering requirements at the data model such as OP-005 must be
applied to ensure that such data is not disclosed. [RFC6973]
provides guidelines for which SACM protocols and information and data
models should follow.
6. References
6.1. Normative References
[RFC7632] Waltermire, D. and D. Harrington, "Endpoint Security
Posture Assessment: Enterprise Use Cases", RFC 7632,
DOI 10.17487/RFC7632, September 2015,
<http://www.rfc-editor.org/info/rfc7632>.
6.2. Informative References
[I-D.ietf-sacm-terminology]
Birkholz, H., Lu, J., Strassner, J., and N. Cam-Winget,
"Security Automation and Continuous Monitoring (SACM)
Terminology", draft-ietf-sacm-terminology-13 (work in
progress), July 2017.
[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,
<http://www.rfc-editor.org/info/rfc5209>.
[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,
<http://www.rfc-editor.org/info/rfc6876>.
[RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
Morris, J., Hansen, M., and R. Smith, "Privacy
Considerations for Internet Protocols", RFC 6973,
DOI 10.17487/RFC6973, July 2013,
<http://www.rfc-editor.org/info/rfc6973>.
[RFC7171] Cam-Winget, N. and P. Sangster, "PT-EAP: Posture Transport
(PT) Protocol for Extensible Authentication Protocol (EAP)
Tunnel Methods", RFC 7171, DOI 10.17487/RFC7171, May 2014,
<http://www.rfc-editor.org/info/rfc7171>.
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Authors' Addresses
Nancy Cam-Winget
Cisco Systems
3550 Cisco Way
San Jose, CA 95134
US
Email: ncamwing@cisco.com
Lisa Lorenzin
Pulse Secure
2700 Zanker Rd., Suite 200
San Jose, CA 95134
US
Email: llorenzin@pulsesecure.net
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