Secure Automation and Continuous Monitoring (SACM) Requirements
draft-ietf-sacm-requirements-04

SACM                                                       N. Cam-Winget
Internet-Draft                                             Cisco Systems
Intended status: Informational                               L. Lorenzin
Expires: September 9, 2015                                  Pulse Secure
                                                           March 8, 2015

    Secure Automation and Continuous Monitoring (SACM) Requirements
                    draft-ietf-sacm-requirements-04

Abstract

   This document defines the scope and set of requirements for the
   Secure Automation and Continuous Monitoring (SACM) architecture, data
   model and protocols.  The requirements and scope are based on the
   agreed upon use cases.

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   This Internet-Draft will expire on September 9, 2015.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Requirements for SACM . . . . . . . . . . . . . . . . . .   3
     2.2.  Requirements for the Architecture . . . . . . . . . . . .   6
     2.3.  Requirements for the Information Model  . . . . . . . . .   7
     2.4.  Requirements for the Data Model . . . . . . . . . . . . .   7
     2.5.  Requirements for Data Model Operations  . . . . . . . . .   9
     2.6.  Requirements for Transport Protocols  . . . . . . . . . .  10
   3.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  11
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
     5.1.  Trust between Provider and Requestor  . . . . . . . . . .  12
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   Today's environment of rapidly-evolving security threats highlights
   the need to automate the sharing of such information while protecting
   user information as well as the systems that store, process, and
   transmit this information.  Security threats can be detected in a
   number of ways.  SACM's 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 particular, for
   the use cases as exemplified in [I-D.ietf-sacm-use-cases].  Also,
   this document uses terminology defined in
   [I-D.ietf-sacm-terminology].

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2.  Requirements

   This document defines requirements based on the SACM use cases
   defined in [I-D.ietf-sacm-use-cases].  This section describes the
   requirements used by SACM to assess and compare candidate data
   models, interfaces, and protocols, to suit the SACM architecture.
   These requirements express characteristics or features that a
   candidate protocol or data model must be capable of offering to
   ensure security and interoperability.

   In order to address the needs for determining, sharing, and using
   posture information, the following tasks should be considered:

   1.  Define the assets.  This is what we want to know about an asset.
       For instance, organizations will want to know what software is
       installed and its many critical security attributes such as patch
       level.

   2.  Resolve what assets actually compose an endpoint.  This requires
       populating the data elements and attributes needed to exchange
       information pertaining to the assets composing an endpoint.

   3.  Determine the expected values for the data elements and
       attributes that need to be evaluated against the actual collected
       instances of asset data.  This is how an organization can express
       its policy for an acceptable data element or attribute value.  A
       system administrator can also identify specific data elements and
       attributes that represent problems, such as vulnerabilities, that
       need to be detected on an endpoint.

   4.  Evaluate the collected instances of the asset data against those
       expressed in the policy.

   5.  Report the results of the evaluation.

2.1.  Requirements for SACM

   Many deployment scenarios can be instantiated to address the above
   tasks and use cases defined in [I-D.ietf-sacm-use-cases].  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 data models, protocols, and
    transports defined by SACM MUST be extensible to allow support for
    non-standard and future extensions.

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    1.  The transport protocol MUST support the ability to add new
        operations while maintaining backwards compatibility.

    2.  The query language MUST allow for general inquiries, as well as
        expression of specific paths to follow; the retrieval of
        specific information based on an event, as well as on a
        continuous basis and the ability to retrieve specific pieces of
        information, specific types or classes of information, and/or
        the entirety of available information.

    3.  The information model MUST accommodate the addition of new data
        types and/or schemas in a backwards compatible fashion.

   G-002  Interoperability: The data models, protocols, and transports
    must be specified with enough details to ensure interoperability.
    [EDITOR Note: Can we remove this requirement?]

   G-003  Scalability: The data models, protocols, and transports MUST
    be scalable.  SACM must support a broad set of deployment scenarios.
    Scalability must be addressed to support:

    *  Large datagrams: It is possible that the size of posture
       assessment information can vary from a single assessment that is
       small in (record or datagram) size to a very large datagram or a
       very large set of assessments.

    *  Large number of providers and consumers: A deployment may consist
       of a very large number of endpoints requiring or producing (or
       both) posture assessment information.

    *  Large number of target endpoints: A deployment may be managing
       information of a very large number of target endpoints.

   G-004  Agility: The data model, protocols, and transports MUST be
    suitably specified to enable implementations to fit into the
    different deployment models and scenarios, including considerations
    for lightweight implementations of data models and transports.

   G-005  Information Extensibility: A method for expressing both
    standard and non-standard (implementation-specific) data attributes
    while avoiding collisions SHOULD be defined.  For interoperability
    and scope boundary, an explicit set of data attributes MUST be
    defined as mandatory to implement.

   G-006  Data Integrity: A method for ensuring data integrity MUST be
    provided.  This method is required to be available (i.e. all data-

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    handling components must support it), but is not required to be used
    in all cases.

   G-007  Data Isolation: A method for partitioning data MUST be
    supported to accommodate considerations such as geographic,
    regulatory, overlay boundaries, and federation, where an
    organization may want to differentiate between information that can
    be shared outside its own domain and information that cannot.  As
    with the requirement for data integrity, this method is required to
    be available (i.e. all data-handling components must support it),
    but is not required to be used in all cases.

   G-008  Versioning and Backward Compatibility: Announcement and
    negotiation of versions, inclusive of existing capabilities (such as
    transport protocols, data models, specific attributes within data
    models, standard attribute expression sets, etc.)  MUST be
    supported.  Negotiation for both versioning and capability is needed
    to accommodate future growth and ecosystems with mixed capabilities.

   G-009  Discovery: There MUST be a mechanism 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), and where to go to get a specific
    piece of that 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  Endpoint Discovery: SACM MUST define the means by which
    endpoints may be discovered.  Use Case 2.1.2 describes the need to
    discover endpoints and their composition.

   G-011  Unsolicited publication, updates, or change modifications with
    filtering MUST be defined: Use Cases 2.1.3, 2.1.4 and 2.1.5 describe
    the need for the data model to support the means for the information
    to be published unsolicited.  Similarly, the data model must support
    the means for a requestor to obtain updates or change modifications
    without constant querying (or polling).  Like the query operation,
    these update notifications must be able to be set up with a filter
    to allow for only a subset of posture assessment information to be
    obtained.

   G-012  Device Interface: the interfaces by which endpoint communicate
    to share endpoint posture information MUST be well defined.

   G-013  Device location and network topology: the SACM architecture
    and interfaces MUST allow for the endpoint (network) location and
    network topology to be modeled and understood.  Where appropriate,

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    the data model and the interfaces SHOULD allow for discovery of
    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.

2.2.  Requirements for the Architecture

   At the simplest abstraction, the SACM architecture represents the
   core components and interfaces needed to perform the production and
   consumption of posture assessment information.  Requirements relating
   to the SACM's architecture include:

   ARCH-001  Scalability: The architectural components MUST account for
    a range of deployments, from very small sets of endpoints to very
    large deployments.

   ARCH-002  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.

   ARCH-003  Separation of Data and Management functions: SACM MUST
    define both the configuration and management of the SACM data models
    and protocols used to transport and share posture assessment
    information.

   ARCH-004  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.

   ARCH-005  Modularity: Announcement and negotiation of functional
    capabilities (such as authentication protocols, authorization
    schemes, data models, transport protocols, etc.) must be supported,
    enabling a SACM component to make inquiries about the capabilities
    of other components in the SACM ecosystem.

   ARCH-006  Role-based Authorization: The SACM architecture MUST be
    capable of effecting role based authorization.  Distinction of

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    endpoints capable and authorized to provide or consume information
    is required to address appropriate access controls.

   ARCH-007  Context-based Authorization: The SACM architecture MUST be
    capable of effecting context based authorization.  Different
    policies (e.g. business, regulatory, etc.) may specify what data may
    be exposed or shared by particular consumers, as well as how
    consumers may be required to share the information.  The context
    defines the composite set of guidelines provided by policy for
    affecting what posture data is allowed to be communicated from
    providers to consumers.

2.3.  Requirements for the Information Model

   The SACM information represents the abstracted representation for the
   Posture Assessment information to be communicated.  SACM data models
   must adhere and comply to the SACM Information Model.  The
   requirements for the SACM information model include:

   IM-001  Extensible Attribute Dictionary: the Information Model MUST
    define the minimum set of attributes for communicating Posture
    Information.  The attributes should be defined within an extensible
    attribute dictionary to enable data models to adhere to SACM's
    required attributes as well as allow for their own extensions.

   IM-002  Ephemerality: The Information Model SHOULD account for the
    Posture information's ephemerality as the data may be provided by a
    requestor either solicited or unsolicited.

   IM-003  Data model negotiation: SACM's Information Model MUST allow
    support for different data models and data model versions.  The SACM
    Information Model MUST include the ability to discover and negotiate
    the use of a particular or any data model.

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 meets the requirements
   defined in this section.

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   The specific requirements for candidate data models include:

   DM-001  The data model MUST define the data attributes as objects
    that MUST be uniquely referenced (e.g. endpoint, IP address, asset).

   DM-002  The data model MAY be structured into modules and submodules
    to allow for data references within a module.  For example, an
    endpoint may be defined as a module that references one or more
    submodules that further describe the one or more assets.
    Constraints and interfaces may further be defined to resolve or
    tolerate ambiguity in the references (e.g. same IP address used in
    two separate networks).

   DM-003  The interfaces and actions in the data model MUST include
    support for rootless searches and wildcard searches.

   DM-004  The search interfaces and actions MUST include the ability to
    start a search anywhere within a data model structure.

   DM-005  The data model SHOULD include management of the data,
    including data lifetime management (longevity or expiration of data)
    and persistence considerations.

   DM-006  Ephemerality: The data model SHOULD include the ability to
    allow providers of data to provide the data as a whole or when
    updates occur.  The data may be provided by a requestor either
    solicited or unsolicited.

   DM-007  The data model SHOULD allow for a loose coupling between the
    provider and the requestor.

   DM-008  The interfaces and actions in the data model MUST include the
    ability to identify data from a specific provider.

   DM-009  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-010  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-011  Provenance: The data model MUST include the ability for
    providers to identify the data origin and provide a method for
    provenance information to be captured and communicated.

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   DM-012  Attribute Dictionary: Use Cases in the whole of Section 2
    describe the need for an attribute dictionary.  With SACM's scope
    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.

   DM-013  Transport Agnostic: the data model SHOULD be transport
    agnostic, to allow for the data operations to leverage the most
    appropriate transport Internet layer (e.g.  Link Layer, TCP, UDP,
    etc.).  [Editor's Note: Per Dan Romanascu's comment, should this
    requirement be removed?  Or perhaps moved to the Data Model
    Operations, whereby the operations should be defined in a transport
    agnostic encapsulation?]

   DM-014  The data model SHOULD allow the provider to include the
    information's origination time.

   DM-015  The data model SHOULD allow the provider to include
    attributes defining how the data was generated (e.g. self-reported,
    reported by aggregator, scan result, etc.).

   DM-016  The data model SHOULD allow the provider to include
    attributes defining the location of the data source.

   DM-017  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-018  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 observations.

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.  The specific requirements for such operations include:

   OP-001  Synchronization: Request and response operations SHOULD 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.

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   OP-002  Collection separation: 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 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 requester.

   OP-004  Attribute-based query: A query operation SHOULD be based on a
    set of 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  Data model scalability: The data model MUST be scalable.  Use
    Cases 2.1.4 and 2.1.5 describes 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  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 enpoint (and their 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.

2.6.  Requirements for Transport Protocols

   The requirements for transport protocols include:

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   T-001  Transport variability: Different transports MUST be supported
    to address different deployment and time constraints.  Supporting
    transports MAY be at the data link layer, network, transport, or
    application layers.

   T-002  Data Integrity: Transport protocols MUST be able to ensure
    data integrity.

   T-003  Data Confidentiality: Transport protocols MUST be able to
    support data confidentiality.  Transport protocols SHOULD ensure
    data protection for data in transit by encryption to provide
    confidentiality, integrity, and robustness against protocol-based
    attacks.  Note that while the transport MUST be able to support data
    confidentiality, implementations MAY choose to make confidentiality
    optional.  Protection for data at rest is not in scope for SACM.
    Data protection MAY be used for both privacy and non-privacy
    scenarios.

   T-004  Transport protection: Transport protocols MUST be capable of
    supporting mutual authentication and replay protection.

   T-005  Transport reliability: Transport protocols MUST provide
    reliable delivery of data.  This includes the ability to perform
    fragmentation and reassembly, and to detect replays.

3.  Acknowledgements

   The authors would like to thank Barbara Fraser, Jim Bieda, and Adam
   Montville for reviewing and contributing to this draft.

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 transports may be
   defined or reused from already existing standards.  This section will
   highlight security considerations that may apply to SACM based on the
   architecture and standards applied in SACM.  In particular,
   highlights to security considerations that may apply to the SACM
   reference architecture and standard data models and transports will
   be discussed

   To address security and privacy considerations, the data model,
   protocols and transport must consider authorization based on consumer
   function and privileges, to only allow authorized consumers and

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   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,
   authorization should be based on both subject (the information
   requestor) and object (the information requested).  The method by
   which this authorization is applied is unspecified.

   With SACM's charter focus on 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
   requestor or devices that are involved in the transport 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 transport 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 requester.  Without appropriate protections

   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 transport 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.

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   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.  As such, providing non-
   repudiation in SACM is out of scope.  However, SACM specifications
   should provide the means for allowing non-repudiation possible and at
   minimum, provide endpoint authentication and transport 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 is 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 transport
      layer.

   o  Either or both confidentiality and integrity at the data layer.

6.  References

6.1.  Normative References

   [I-D.ietf-sacm-terminology]
              Waltermire, D., Montville, A., Harrington, D., Cam-Winget,
              N., Lu, J., Ford, B., and M. Kaeo, "Terminology for
              Security Assessment", draft-ietf-sacm-terminology-06 (work
              in progress), February 2015.

   [I-D.ietf-sacm-use-cases]
              Waltermire, D. and D. Harrington, "Endpoint Security
              Posture Assessment - Enterprise Use Cases", draft-ietf-
              sacm-use-cases-08 (work in progress), February 2015.

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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5209]  Sangster, P., Khosravi, H., Mani, M., Narayan, K., and J.
              Tardo, "Network Endpoint Assessment (NEA): Overview and
              Requirements", RFC 5209, June 2008.

6.2.  Informative References

   [RFC3444]  Pras, A. and J. Schoenwaelder, "On the Difference between
              Information Models and Data Models", RFC 3444, January
              2003.

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

Cam-Winget & Lorenzin   Expires September 9, 2015              [Page 14]