| SACM | D. Waltermire, Ed. |
| Internet-Draft | NIST |
| Intended status: Standards Track | K. Watson |
| Expires: January 9, 2017 | DHS |
| C. Kahn | |
| L. Lorenzin | |
| Pulse Secure, LLC | |
| M. Cokus | |
| D. Haynes | |
| The MITRE Corporation | |
| July 8, 2016 |
SACM Information Model
draft-ietf-sacm-information-model-06
This document defines the Information Elements that are transported between SACM components and their interconnected relationships. The primary purpose of the Secure Automation and Continuous Monitoring (SACM) Information Model is to ensure the interoperability of corresponding SACM data models and addresses the use cases defined by SACM. The Information Elements and corresponding types are maintained as the IANA "SACM Information Elements" registry.
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-Drafts is at http://datatracker.ietf.org/drafts/current/.
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 January 9, 2017.
Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
The SACM Information Model (IM) serves multiple purposes:
A complete set of requirements imposed on the IM can be found in [I-D.ietf-sacm-requirements]. The SACM IM is intended to be used for standardized data exchange between SACM components (data in motion). Nevertheless, the Information Elements (IE) and their relationships defined in this document can be leveraged to create and align corresponding data models for data at rest.
The information model expresses, for example, target endpoint (TE) attributes, guidance, and evaluation results. The corresponding Information Elements are consumed and produced by SACM components as they carry out tasks.
The primary tasks that this information model supports (on data, control, and management plane) are:
These tasks are defined in [I-D.ietf-sacm-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 RFC 2119 [RFC2119].
The notation used to define the SACM Information Elements (IEs) is based on a customized version of the IPFIX information model syntax [RFC7012] which is described in Figure 2. However, there are several examples presented throughout the document that use a simplified pseudo-code to illustrate the basic structure. It should be noted that while they include actual names of subjects and attributes as well as values, they are not intended to influence how corresponding SACM IEs should be defined in Section 7. The examples are provided for demonstration purposes only.
The IEs defined in this document comprise the building blocks by which all SACM content is composed. They are consumed and provided by SACM components on the data plane. Every Information Element has a unique label: its name. Every type of IE defined by the SACM IM is registered as a type at the IANA registry. The Integer Index of the IANA SMI number tables can be used by SACM data models.
The IEs in this information model represent information related to assets in the following areas (based on the use cases described in [RFC7632]):
A SACM data model based on this information model MAY include additional information elements that are not defined here. The labels of additional Information Elements included in different SACM data models MUST NOT conflict with the labels of the Information Elements defined by this information model, and the names of additional Information Elements MUST NOT conflict with each other or across multiple data models. In order to avoid naming conflicts, the labels of additional IEs SHOULD be prefixed to avoid collisions across extensions. The prefix MUST include an organizational identifier and therefore, for example, MAY be an IANA enterprise number, a (partial) name space URI, or an organization name abbreviation.
There are two basic types of IEs:
hostname = "arbutus"
coordinates = (
latitude = N27.99619,
longitude = E86.92761
)
Figure 1: Example instance of an attribute and subject.
In general, every piece of information that enables security posture assessment or further enriches the quality of the assessment process can be associated with metadata. In the SACM IM, metadata is represented by specific subjects and is bundled with other attributes or subjects to provide additional information about them. The IM explicitly defines two kinds of metadata:
Metadata can also include relationships that refer to other associated IEs (or SACM content in general) by using referencing labels that have to be included in the metadata of the associated IE.
Subjects can be nested and the SACM IM allows for circular or recursive nesting. The association of IEs via nesting results in a tree-like structure wherein subjects compose the root and intermediary nodes and attributes the leaves of the tree. This semantic structure does not impose a specific structure on SACM data models regarding data in motion or data repository schemata for data at rest.
The SACM IM provides two conceptual top-level subjects that are used to ensure a homogeneous structure for SACM content and its associated metadata: SACM statements and SACM content-elements. Every set of IEs that is provided by a SACM component must provide the information contained in these two subjects although it is up to the implementer whether or not the subjects are explicitly defined in a data model.
The notation the SACM IM is defined in is based on a modified version of the IP Information Flow Export (IPFIX) Information Model syntax described in Section 2.1 of [RFC7012]. The customized syntax used by the SACM IM is defined below in Figure 2.
elementId (required): The numeric identifier of the
Information Element. It is used
for the compact identification
of an Information Element. If
this identifier is used without
an enterpriseID, then the
elementId must be unique, and
the description of allowed values
is administrated by IANA. The
value "TBD" may be used during
development of the information
model until an elementId is
assigned by IANA and filled
in at publication time.
enterpriseId (optional): Enterprises may wish to define
Information Elements without
registering them with IANA, for
example, for enterprise-internal
purposes. For such Information
Elements, the elementId is
not sufficient when used
outside the enterprise. If
specifications of enterprise-
specific Information Elements
are made public and/or if
enterprise-specific identifiers
are used by SACM components
outside the enterprise, then the
enterprise-specific identifier
MUST be made globally unique by
combining it with an enterprise
identifier. Valid values for the
enterpriseId are defined by IANA
as Structure of Management
Information (SMI) network management
private enterprise numbers.
name (required): A unique and meaningful name for
the Information Element.
dataType (required): There are two kinds of datatypes:
simple and structured. Attributes are
defined using simple datatypes
and subjects are defined using
structured datatypes. The contents of
the datatype field will be either
a reference to one of the simple
datatypes listed in Section
5.1, or the specification of
structured datatype as defined in
Section 5.2.
status (required): The status of the specification
of the Information Element.
Allowed values are "current" and
"deprecated". All newly defined
Information Elements have "current"
status. The process for moving
Information Elements to the
"deprecated" status is TBD.
description (required): Describes the meaning of the
Information Element, how it is
derived, conditions for its use,
etc.
For Information Elements that
represent flags, please include
a table that lists each flag value
(hexadecimal) and description. The
following is a template for that
table.
+-------+-----------------------+
| Value | Description |
+-------+-----------------------+
| | |
+-------+-----------------------+
references (optional): Identifies other RFCs or documents
outside the IETF which provide
additional information or context
about the Information Element.
Figure 2: Information Element Specification Template
Every piece of information that is provided by a SACM component is always associated with a set of metadata, for example, the timestamp at which this set of information was produced (e.g. by a collection task) or what target endpoint this set of information is about (e.g. the data-source or a target endpoint identifier, respectively). The subject that associates content IE with content-metadata IE is called a content-element. Content metadata can also include relationships that express associations with other content-elements.
content-element = (
content-metadata = (
collection-timestamp = 146193322,
data-source = fb02e551-7101-4e68-8dec-1fde6bd10981
),
hostname = "arbutus",
coordinates = (
latitude = N27.99619,
longitude = E86.92761
)
)
Figure 3: Example set of IEs associated with a timestamp and a target endpoint label.
One or more SACM content elements are bundled in a SACM statement. In contrast to content-metadata, statement-metatdata focuses on the providing SACM component instead of the target endpoint that the content is about. The only content-specific metadata included in the SACM statement is the content-type IE. Therefore, multiple content-elements that share the same statement metadata and are of the same content-type can be included in a single SACM statement. A SACM statement functions similar to an envelope or a header. Its purpose is to enable the tracking of the origin of data inside a SACM domain and more importantly to enable the mitigation of conflicting information that my originate from different SACM components. How a consuming SACM component actually deals with conflicting information is out-of-scope of the SACM IM. Semantically, the term statement implies that the SACM content provided by a SACM component might not be correct in every context, but rather is the result of an best-effort to produce correct information.
sacm-statement = (
statement-metadata = (
publish-timestamp = 1461934031,
data-origin = 24e67957-3d31-4878-8892-da2b35e121c2,
content-type = observation
),
content-element = (
content-metadata = (
collection-timestamp = 146193322,
data-source = fb02e551-7101-4e68-8dec-1fde6bd10981
),
hostname = "arbutus"
)
)
Figure 4: Example of a simple SACM statement including a single content-element.
sacm-statement = (
statement-metadata = (
publish-timestamp = 1461934031,
data-origin = 24e67957-3d31-4878-8892-da2b35e121c2
content-type = observation
),
content-element = (
content-metadata = (
collection-timestamp = 146193322,
data-source = fb02e551-7101-4e68-8dec-1fde6bd10981
),
coordinates = (
latitude = N27.99619,
longitude = E86.92761
)
)
)
sacm-statement = (
statement-metadata = (
publish-timestamp = 1461934744,
data-origin = e42885a1-0270-44e9-bb5c-865cf6bd4800,
content-type = observation
),
content-element = (
content-metadata = (
collection-timestamp = 146193821,
te-label = fb02e551-7101-4e68-8dec-1fde6bd10981
),
coordinates = (
latitude = N16.67622,
longitude = E141.55321
)
)
)
Figure 5: Example of conflicting information originating from different SACM components.
An IE can be associated with another IE, e.g. a user-name attribute can be associated with a content-authorization subject. These references are expressed via the relationships subject, which can be included in a corresponding content-metadata subject. The relationships subject includes a list of one or more references. The SACM IM does not enforce a SACM domain to use unique identifiers as references. Therefore, there are at least two ways to reference another content-element:
It is recommended to provide unique identifiers in a SACM domain and the SACM IM provides a corresponding naming-convention as a reference in section FIXME. The alternative highlighted above summarizes a valid approach that does not require unique identifiers and is similar to the approach of referencing target endpoints via identifying attributes included in a characterization record (FIXME REF arch).
content-element = (
content-metadata = (
collection-timestamp = 1461934031,
te-label =
fb02e551-7101-4e68-8dec-1fde6bd10981
relationships = (
associated-with-user-account =
f3d70ef4-7e18-42af-a894-8955ba87c95d
)
),
hostname = "arbutus"
)
content-element = (
content-metadata = (
content-label = f3d70ef4-7e18-42af-a894-8955ba87c95d
),
user-account = (
username = romeo
authentication = local
)
)
Figure 6: Example instance of a content-element subject associated with another subject via its content metadata.
Event subjects provide a structure to represent the change of IE values that was detected by a collection task at a specific point of time. It is mandatory to include the new values and the collection timestamp in an event subject and it is recommended to include the past values and a collection timestamp that were replaced by the new IE values. Every event can also be associated with a subject-specific event-timestamp and a lastseen-timestamp that might differ from the corresponding collection-timestamps. If these are omitted the collection-timestamp that is included in the content-metadata subject is used instead.
sacm-statement = (
statement-metadata = (
publish-timestamp = 1461934031,
data-origin = 24e67957-3d31-4878-8892-da2b35e121c2,
content-type = event
),
event = (
event-attributes = (
event-name = "host-name change",
content-element = (
content-metadata = (
collection-timestamp = 146193322,
data-source =
fb02e551-7101-4e68-8dec-1fde6bd10981,
event-component = past-state
),
hostname = "arbutus"
),
content-element = (
content-metadata = (
collection-timestamp = 146195723,
data-source =
fb02e551-7101-4e68-8dec-1fde6bd10981,
event-component = current-state
),
hostname = "lilac"
)
)
)
Figure 7: Example of a SACM statement containing an event.
Categories are special IEs that enable to refer to multiple types of IE via just one name. Therefore, they are similar to a type-choice. A prominent example of a category is network-address. Network-address is a category that every kind of network address is associated with, e.g. mac-address, ipv4-address, ipv6-address, or typed-network-address. If a subject includes network-address as one of its components, any of the category members are valid to be used in its place.
Another prominent example is EndpointIdentifier. Some IEs can be used to identify (and over time re-recognize) target endpoints - those are associated with the category endpoint-identifier.
TODO: In the IETF, there are privacy concerns with respect to endpoint identity and monitoring. As a result, the Endpoint ID Design Team proposes that "endpoint identity" be changed to "endpoint designation". Designation attributes can be used to correlate endpoints, information about endpoints, events, etc. NOTE: Designation attributes are just those that are mandatory-to-implement. In practice, organizations may need to select additional attributes beyond the mandatory-to-implement attributes to successfully identify an endpoint on their network. Operational and privacy concerns will be covered in Operational Considerations and Privacy Considerations sections respectively. A proposal outlining various options for representing designation attributes/objects in the IPFIX syntax is being discussed on the mailing list. See IM issue #39 at https://github.com/sacmwg/draft-ietf-sacm-information-model/issues/39 for more information. Also, consider inserting table that discusses the various properties of designation attributes and include it in this section to help others determine whether or not a new Information Element should be considered a designation attribute. Lastly, explain how designation attributes can be used. For example, letting a consumer identify an endpoint, for two purposes:
TODO: In the IETF, there are privacy concerns with respect to endpoint identity and monitoring. As a result, it was proposed that a privacy property be included to denote when a Information Element represents a privacy concern. A proposal outlining various options for representing privacy attributes/objects in the IPFIX syntax is being discussed on the mailing list. See IM issue #39 at https://github.com/sacmwg/draft-ietf-sacm-information-model/issues/39 for more information.
This section describes the set of valid abstract data types that can be used for the specification of the SACM Information Elements in Section 7. SACM currently supports two classes of datatypes that can be used to define Information Elements.
Note that further abstract data types may be specified by future extensions of the SACM information model.
To facilitate the use of existing work, SACM supports the following abstract data types defined in Section 3 of [RFC7012].
The type "ciscoTrainSoftwareVersion" represents a software version that conforms to the Cisco IOS Train string format.
The type "rpmSoftwareVersion" represents a software version that conforms to the EPOCH:VERSION-RELEASE format.
The type "simpleSoftwareVersion" represents a software version that is a hierarchical list of non-negative integers separated by a single character delimiter.
SACM defines the following abstract list data types that are used to represent the structured data associated with subjects.
The notation for defining a SACM structured datatype is based on regular expressions, which are composed of the keywords "list" or "orderedList" and an Information Element expression. IE expressions use some of the regular expression syntax and operators, but the terms in the expression are the names of defined Information Elements instead of character classes. The syntax for defining list and orderedList datatypes is described below, using BNF:
<list-def> -> ("list"|"orderedList") "(" <ie-expression> ")"
<ie-expression> -> <ie-name> <cardinality>?
( ("," | "|") <ie-name> <cardinality>?)*
<cardinality> -> "*" | "+" | "?" |
( "(" <non-neg-int> ("," <non-neg-int>)? ")" )
Figure 8: Syntax for Defining List Datatypes
As seen above, multiple occurences of an Information Element may be present in a structured datatype. The cardinality of an Information Element within a structured Information Element definition is defined by the following operators:
* - zero or more occurrences
+ - one or more occurrences
? - zero or one occurrence
(m,n) - between m and n occurrences
Figure 9: Specifying Cardinality for Structured Datatypes
The absence of a cardinality operator implies one mandatory occurrence of the Information Element.
Below is an example of a structured Information Element definition.
personInfo = list(firstName, middleNames?, lastName)
firstName = string
middleNames = orderedList(middleName+)
middleName = string
lastName = string
As an example, consider the name "John Ronald Reuel Tolkien".
Below are instances of this name, structured according to the
personInfo definition.
personInfo = (firstName="John", middleNames(middleName="Ronald",
middleName="Reuel"), lastName="Tolkien")
personInfo = (middleNames(middleName="Ronald", middleName=" Reuel"),
lastName="Tolkien", firstName="John")
The instance below is not legal with respect to the definition
of personInfo because the order in middleNames is not preserved.
personInfo = (firstName="John", middleNames(middleName=" Reuel",
middleName="Ronald"), lastName="Tolkien")
Figure 10: Example of Defining a Structured Datatype
In order to represent the Information Elements related to the areas listed in Section 3.1, the information model defines the information needs (or metadata about those information needs) related to following types of assets which arse defined in [I-D.ietf-sacm-terminology] (and included below for convenience) which are of interest to SACM. Specifically:
The following figure shows the make up of an Endpoint asset which contains zero or more hardware components and zero or more software components each of which may have zero or more instances running an endpoint at any given time as well as zero or more identities that act on behalf of the endpoint when interfacing with other endpoints, tools, or services. An endpoint may also contain other endpoints in the case of a virtualized environment.
+---------+*______in>_______*+-----+
|Hardware | |! !|
|Component| +---------+ |! !|
+---------+ |Software |in> |! !|
|Component|____|! !|
+---------+* *|! !|
1| |! !|
*| | | +----------+
+---------+ |End- |*_____*| Identity |
|Software |in> |point| acts +----------+
|Instance |____| | for>
+---------+* 1|! !|
|! !|
|! !|
|! !|
|! !|____
|! !|0..1|
+-----+ |
|* |
|_______|
in>
Figure 11: Model of an Endpoint
As defined in [RFC4949], an asset is a system resource that is (a) required to be protected by an information system's security policy, (b) intended to be protected by a countermeasure, or (c) required for a system's mission.
In the scope of SACM, an asset can be composed of other assets. Examples of Assets include: Endpoints, Software, Guidance, or Identity. Furthermore, an asset is not necessarily owned by an organization.
From [RFC5209], an endpoint is any computing device that can be connected to a network. Such devices normally are associated with a particular link layer address before joining the network and potentially an IP address once on the network. This includes: laptops, desktops, servers, cell phones, or any device that may have an IP address.
To further clarify, an endpoint is any physical or virtual device that may have a network address. Note that, network infrastructure devices (e.g. switches, routers, firewalls), which fit the definition, are also considered to be endpoints within this document.
Physical endpoints are always composites that are composed of hardware components and software components. Virtual endpoints are composed entirely of software components and rely on software components that provide functions equivalent to hardware components.
The SACM architecture differentiates two essential categories of endpoints: Endpoints whose security posture is intended to be assessed (target endpoints) and endpoints that are specifically excluded from endpoint posture assessment (excluded endpoints).
Hardware components are the distinguishable physical components that compose an endpoint. The composition of an endpoint can be changed over time by adding or removing hardware components. In essence, every physical endpoint is potentially a composite of multiple hardware components, typically resulting in a hierarchical composition of hardware components. The composition of hardware components is based on interconnects provided by specific hardware types (e.g. mainboard is a hardware type that provides local busses as an interconnect). In general, a hardware component can be distinguished by its serial number.
Examples of a hardware components include: motherboards, network interfaces, graphics cards, hard drives, etc.
A software package installed on an endpoint (including the operating system) as well as a unique serial number if present (e.g. a text editor associated with a unique license key).
It should be noted that this includes both benign and harmful software packages. Examples of benign software components include: applications, patches, operating system kernel, boot loader, firmware, code embedded on a webpage, etc. Examples of malicious software components include: malware, trojans, viruses, etc.
A running instance of the software component (e.g. on a multi-user system, one logged-in user has one instance of a text editor running and another logged-in user has another instance of the same text editor running, or on a single-user system, a user could have multiple independent instances of the same text editor running).
TODO: Define an Asset Identity asset. NOTE: Make sure it is clear that this is not identity in the sense of what we have been saying endpoint identity (now designation).
Examples of an identity include: username, user and device certificates, etc.
TODO: Need to resolve the forms of Guidance in the terminology and those listed as sub-sections below.
Guidance is input instructions to processes and tasks, such as collection or evaluation. Guidance influences the behavior of a SACM component and is considered content of the management plane. Guidance can be manually or automatically generated or provided. Typically, the tasks that provide guidance to SACM components have a low-frequency and tend to be be sporadic. A prominent example of guidance are target endpoint profiles, but guidance can have many forms, including:
An internal collector may need guidance to govern what it collects and when.
An external collector may need guidance to govern what it collects and when.
An evaluator typically needs Evaluation Guidance to govern what it considers to be a good or bad security posture.
A SACM deployment may retain posture attributes, events, or evaluation results for some time. Retention supports ad hoc reporting and other use cases.
If information is retained, retention guidance controls what is retained and for how long.
If two or more pieces of retention guidance apply to a piece of information, the guidance calling for the longest retention should take precedence.
Evaluation results are the resulting values from having evaluated a set of posture attributes.
An example is: a NEA access recommendation [RFC5793].
An evaluator may be able to evaluate better if history is available. This is a use case for retaining Endpoint Attribute Assertions for a time.
An Evaluation Result may be retained longer than the Endpoint Attribute Assertions from which it derives (Figure 11 does not show this). In the limiting case, Endpoint Attribute Assertions are not retained. When an Endpoint Attribute Assertion arrives, an evaluator produces an Evaluation Result. These mechanics are out of the scope of the Information Model.
TODO: Define specific subjects, attributes, and metadata. We may want to consider adding small diagrams showing the relationships between each (see Lisa's notes: https://mailarchive.ietf.org/arch/msg/sacm/kWxlnboHAXD87cned9WavwPZy5w). This may be too much work, but, not sure yet.
elementId: TBD
name: hardwareSerialNumber
dataType: string
status: current
description: A globally unique identifier for a particular
piece of hardware assigned by the vendor.
elementId: TBD
name: interfaceName
dataType: string
status: current
description: A short name uniquely describing an interface,
eg "Eth1/0". See [RFC2863] for the definition
of the ifName object.
elementId: TBD
name: interfaceIndex
dataType: unsigned32
status: current
description: The index of an interface installed on an endpoint.
The value matches the value of managed object
'ifIndex' as defined in [RFC2863]. Note that ifIndex
values are not assigned statically to an interface
and that the interfaces may be renumbered every time
the device's management system is re-initialized,
as specified in [RFC2863].
elementId: TBD
name: interfaceMacAddress
dataType: macAddress
status: current
description: The IEEE 802 MAC address associated with a network
interface on an endpoint.
elementId: TBD
name: interfaceType
dataType: unsigned32
status: current
description: The type of a network interface. The value matches
the value of managed object 'ifType' as defined in
[IANA registry ianaiftype-mib].
elementId: TBD
name: interfaceFlags
dataType: unsigned16
status: current
description: This information element specifies the flags
associated with a network interface. Possible
values include:
| Value | Description |
|---|---|
| 0x1 | interface is up |
| 0x2 | broadcast address valid |
| 0x4 | turn on debugging |
| 0x8 | is a loopback net |
| 0x10 | interface is point-to-point link |
| 0x20 | avoid use of trailers |
| 0x40 | resources allocated |
| 0x80 | no address resolution protocol |
| 0x100 | receive all packets |
elementId: TBD
name: networkInterface
dataType: orderedList(interfaceName, interfaceIndex, macAddress,
ifType, flags)
status: current
description: Information about a network interface
installed on an endpoint. The
following high-level digram
describes the structure of
networkInterface information
element.
elementId: TBD
name: softwareIdentifier
dataType: string
status: current
description: A globally unique identifier for a particular
software application.
elementId: TBD
name: softwareTitle
dataType: string
status: current
description: The title of the software application.
elementId: TBD
name: softwareCreator
dataType: string
status: current
description: The software developer (e.g., vendor or author).
elementId: TBD
name: simpleSoftwareVersion
dataType: simpleVersion
status: current
description: The version string for a software application that
follows the simple versioning scheme.
elementId: TBD
name: rpmSoftwareVersion
dataType: rpmVersion
status: current
description: The version string for a software application that
follows the RPM versioning scheme.
elementId: TBD
name: ciscoTrainSoftwareVersion
dataType: ciscoTrainVersion
status: current
description: The version string for a software application that
follows the Cisco Train Release versioning scheme.
elementId: TBD
name: softwareVerison
dataType: list(simpleSoftwareVersion | rpmSoftwareVersion |
ciscoTrainSoftwareVersion)
status: current
description: The version of the software application. Software
applications may be versioned using a number of
schemas. The following high-level digram describes
the structure of the softwareVersion information
element.
elementId: TBD
name: lastUpdated
dataType: dateTimeSeconds
status: current
description: The date and time when the software instance
was last updated on the system (e.g., new
version instlalled or patch applied)
elementId: TBD
name: softwareInstance
dataType: orderedList(softwareIdentifier, title, creator,
softwareVersion, lastUpdated)
status: current
description: Information about an instance of software
installed on an endpoint. The following
high-level digram describes the structure of
softwareInstance information element.
elementId: TBD
name: globallyUniqueIdentifier
dataType: unsigned8
status: current
metadata: true
description: TODO.
elementId: TBD
name: dataOrigin
dataType: string
status: current
metadata: true
description: The origin of the data. TODO make a better
description.
elementId: TBD
name: dataSource
dataType: string
status: current
metadata: true
description: The source of the data. TODO make a better
description.
elementId: TBD
name: creationTimestamp
dataType: dateTimeSeconds
status: current
metadata: true
description: The date and time when the posture
information was created by a SACM Component.
elementId: TBD
name: collectionTimestamp
dataType: dateTimeSeconds
status: current
metadata: true
description: The date and time when the posture
information was collected or observed by a SACM
Component.
elementId: TBD
name: publicationTimestamp
dataType: dateTimeSeconds
status: current
metadata: true
description: The date and time when the posture
information was published.
elementId: TBD
name: relayTimestamp
dataType: dateTimeSeconds
status: current
metadata: true
description: The date and time when the posture
information was relayed to another SACM Component.
elementId: TBD
name: storageTimestamp
dataType: dateTimeSeconds
status: current
metadata: true
description: The date and time when the posture
information was stored in a Repository.
elementId: TBD
name: type
dataType: unsigned16
status: current
metadata: true
description: The type of data model use to represent
some set of endpoint information. The following
table lists the set of data models supported by SACM.
+-------+----------------------------------+
| Value | Description |
+-------+----------------------------------+
| 0x00 | Data Model 1 |
+-------+----------------------------------+
| 0x01 | Data Model 2 |
+-------+----------------------------------+
| 0x02 | Data Model 3 |
+-------+----------------------------------+
|... | ... |
+-------+----------------------------------+
elementId: TBD
name: protocolIdentifier
dataType: unsigned8
status: current
description: The value of the protocol number in the IP packet
header. The protocol number identifies the IP packet
payload type. Protocol numbers are defined in the
IANA Protocol Numbers registry.
In Internet Protocol version 4 (IPv4), this is
carried in the Protocol field. In Internet Protocol
version 6 (IPv6), this is carried in the Next Header
field in the last extension header of the packet.
elementId: TBD
name: sourceTransportPort
dataType: unsigned16
status: current
description: The source port identifier in the transport header.
For the transport protocols UDP, TCP, and SCTP, this
is the source port number given in the respective
header. This field MAY also be used for future
transport protocols that have 16-bit source port
identifiers.
elementId: TBD
name: sourceIPv4PrefixLength
dataType: unsigned8
status: current
description: The number of contiguous bits that are relevant in
the sourceIPv4Prefix Information Element.
elementId: TBD
name: ingressInterface
dataType: unsigned32
status: current
description: The index of the IP interface where packets of this
Flow are being received. The value matches the
value of managed object 'ifIndex' as defined in
[RFC2863]. Note that ifIndex values are not assigned
statically to an interface and that the interfaces
may be renumbered every time the device's management
system is re-initialized, as specified in [RFC2863].
elementId: TBD
name: destinationTransportPort
dataType: unsigned16
status: current
description: The destination port identifier in the transport
header. For the transport protocols UDP, TCP, and
SCTP, this is the destination port number given in
the respective header. This field MAY also be used
for future transport protocols that have 16-bit
destination port identifiers.
elementId: TBD
name: sourceIPv6PrefixLength
dataType: unsigned8
status: current
description: The number of contiguous bits that are relevant in
the sourceIPv6Prefix Information Element.
elementId: TBD name: sourceIPv4Prefix dataType: ipv4Address status: current description: IPv4 source address prefix.
elementId: TBD name: destinationIPv4Prefix dataType: ipv4Address status: current description: IPv4 destination address prefix.
elementId: TBD name: sourceMacAddress dataType: macAddress status: current description: The IEEE 802 source MAC address field.
elementId: TBD name: ipVersion dataType: unsigned8 status: current description: The IP version field in the IP packet header.
elementId: TBD
name: interfaceDescription
dataType: string
status: current
description: The description of an interface, eg "FastEthernet
1/0" or "ISP
connection".
elementId: TBD name: applicationDescription dataType: string status: current description: Specifies the description of an application.
elementId: TBD name: applicationId dataType: octetArray status: current description: Specifies an Application ID per [RFC6759].
elementId: TBD name: applicationName dataType: string status: current description: Specifies the name of an application.
elementId: TBD
name: exporterIPv4Address
dataType: ipv4Address
status: current
description: The IPv4 address used by the Exporting Process.
This is used by the Collector to identify the
Exporter in cases where the identity of the Exporter
may have been obscured by the use of a proxy.
elementId: TBD
name: exporterIPv6Address
dataType: ipv6Address
status: current
description: The IPv6 address used by the Exporting Process.
This is used by the Collector to identify the
Exporter in cases where the identity of the
Exporter may have been obscured by the use of a
proxy.
elementId: TBD
name: portId
dataType: unsigned32
status: current
description: An identifier of a line port that is unique per
IPFIX Device hosting an Observation Point.
Typically, this Information Element is used for
limiting the scope of other Information Elements.
elementId: TBD
name: templateId
dataType: unsigned16
status: current
description: An identifier of a Template that is locally unique
within a combination of a Transport session and an
Observation Domain.
Template IDs 0-255 are reserved for Template Sets,
Options Template Sets, and other reserved Sets yet
to be created. Template IDs of Data Sets are
numbered from 256 to 65535.
Typically, this Information Element is used for
limiting the scope of other Information Elements.
Note that after a re-start of the Exporting Process
Template identifiers may be re-assigned.
elementId: TBD
name: collectorIPv4Address
dataType: ipv4Address
status: current
description: An IPv4 address to which the Exporting Process sends
Flow information.
elementId: TBD
name: collectorIPv6Address
dataType: ipv6Address
status: current
description: An IPv6 address to which the Exporting Process sends
Flow information.
elementId: TBD
name: informationElementIndex
dataType: unsigned16
status: current
description: A zero-based index of an Information Element
referenced by informationElementId within a Template
referenced by templateId; used to disambiguate
scope for templates containing multiple identical
Information Elements.
elementId: TBD
name: informationElementId
dataType: unsigned16
status: current
description: This Information Element contains the ID of another
Information Element.
elementId: TBD
name: informationElementDataType
dataType: unsigned8
status: current
description: A description of the abstract data type of an IPFIX
information element.These are taken from the
abstract data types defined in section 3.1 of the
IPFIX Information Model [RFC5102]; see that section
for more information on the types described in the
informationElementDataType sub-registry.
These types are registered in the IANA IPFIX
Information Element Data Type subregistry. This
subregistry is intended to assign numbers for type
names, not to provide a mechanism for adding data
types to the IPFIX Protocol, and as such requires a
Standards Action [RFC5226] to modify.
elementId: TBD
name: informationElementDescription
dataType: string
status: current
description: A UTF-8 [RFC3629] encoded Unicode string containing
a human-readable description of an Information
Element. The content of the
informationElementDescription MAY be annotated with
one or more language tags [RFC4646], encoded
in-line [RFC2482] within the UTF-8 string, in order
to specify the language in which the description is
written. Description text in multiple languages MAY
tag each section with its own language tag; in this
case, the description information in each language
SHOULD have equivalent meaning. In the absence of
any language tag, the "i-default" [RFC2277] language
SHOULD be assumed. See the Security Considerations
section for notes on string handling for Information
Element type records.
elementId: TBD
name: informationElementName
dataType: string
status: current
description: A UTF-8 [RFC3629] encoded Unicode string containing
the name of an Information Element, intended as a
simple identifier. See the Security Considerations
section for notes on string handling for Information
Element type records.
elementId: TBD
name: informationElementRangeBegin
dataType: unsigned64
status: current
description: Contains the inclusive low end of the range of
acceptable values for an Information Element.
elementId: TBD
name: informationElementRangeEnd
dataType: unsigned64
status: current
description: Contains the inclusive high end of the range of
acceptable values for an Information Element.
elementId: TBD
name: informationElementSemantics
dataType: unsigned8
status: current
description: A description of the semantics of an IPFIX
Information Element. These are taken from the data
type semantics defined in section 3.2 of the IPFIX
Information Model [RFC5102]; see that section for
more information on the types defined in the
informationElementSemantics sub-registry. This
field may take the values in Table ; the special
value 0x00 (default) is used to note that no
semantics apply to the field; it cannot be
manipulated by a Collecting Process or File Reader
that does not understand it a priori.
These semantics are registered in the IANA IPFIX
Information Element Semantics subregistry. This
subregistry is intended to assign numbers for
semantics names, not to provide a mechanism for
adding semantics to the IPFIX Protocol, and as such
requires a Standards Action [RFC5226] to modify.
elementId: TBD
name: informationElementUnits
dataType: unsigned16
status: current
description: A description of the units of an IPFIX Information
Element. These correspond to the units implicitly
defined in the Information Element definitions in
section 5 of the IPFIX Information Model [RFC5102];
see that section for more information on the types
described in the informationElementsUnits
sub-registry. This field may take the values in
Table 3 below; the special value 0x00 (none) is
used to note that the field is unitless.
These types are registered in the IANA IPFIX
Information Element Units subregistry; new types
may be added on a First Come First Served [RFC5226]
basis.
elementId: TBD name: userName dataType: string status: current description: User name associated with the flow.
elementId: TBD
name: applicationCategoryName
dataType: string
status: current
description: An attribute that provides a first level
categorization for each Application ID.
elementId: TBD
name: mibObjectValueInteger
dataType: signed64
status: current
description: An IPFIX Information Element which denotes that the
integer value of a MIB object will be exported.
The MIB Object Identifier ("mibObjectIdentifier")
for this field MUST be exported in a MIB Field
Option or via another means. This Information
Element is used for MIB objects with the Base
Syntax of Integer32 and INTEGER with IPFIX Reduced
Size Encoding used as required. The value is
encoded as per the standard IPFIX Abstract Data Type
of signed64.
elementId: TBD
name: mibObjectValueOctetString
dataType: octetArray
status: current
description: An IPFIX Information Element which denotes that an
Octet String or Opaque value of a MIB object will
be exported. The MIB Object Identifier
("mibObjectIdentifier") for this field MUST be
exported in a MIB Field Option or via another means.
This Information Element is used for MIB objects
with the Base Syntax of OCTET STRING and Opaque. The
value is encoded as per the standard IPFIX Abstract
Data Type of octetArray.
elementId: TBD
name: mibObjectValueOID
dataType: octetArray
status: current
description: An IPFIX Information Element which denotes that an
Object Identifier or OID value of a MIB object will
be exported. The MIB Object Identifier
("mibObjectIdentifier") for this field MUST be
exported in a MIB Field Option or via another means.
This Information Element is used for MIB objects
with the Base Syntax of OBJECT IDENTIFIER. Note -
In this case the "mibObjectIdentifier" will define
which MIB object is being exported while the value
contained in this Information Element will be an
OID as a value. The mibObjectValueOID Information
Element is encoded as ASN.1/BER [BER] in an
octetArray.
elementId: TBD
name: mibObjectValueBits
dataType: octetArray
status: current
description: An IPFIX Information Element which denotes that a
set of Enumerated flags or bits from a MIB object
will be exported. The MIB Object Identifier
("mibObjectIdentifier") for this field MUST be
exported in a MIB Field Option or via another means.
This Information Element is used for MIB objects
with the Base Syntax of BITS. The flags or bits are
encoded as per the standard IPFIX Abstract Data Type
of octetArray, with sufficient length to accommodate
the required number of bits. If the number of bits
is not an integer multiple of octets then the most
significant bits at end of the octetArray MUST be
set to zero.
elementId: TBD
name: mibObjectValueIPAddress
dataType: ipv4Address
status: current
description: An IPFIX Information Element which denotes that the
IPv4 Address of a MIB object will be exported. The
MIB Object Identifier ("mibObjectIdentifier") for
this field MUST be exported in a MIB Field Option
or via another means. This Information Element is
used for MIB objects with the Base Syntax of
IPaddress. The value is encoded as per the standard
IPFIX Abstract Data Type of ipv4Address.
elementId: TBD
name: mibObjectValueCounter
dataType: unsigned64
status: current
description: An IPFIX Information Element which denotes that the
counter value of a MIB object will be exported.
The MIB Object Identifier ("mibObjectIdentifier")
for this field MUST be exported in a MIB Field
Option or via another means. This Information
Element is used for MIB objects with the Base
Syntax of Counter32 or Counter64 with IPFIX Reduced
Size Encoding used as required. The value is encoded
as per the standard IPFIX Abstract Data Type
of unsigned64.
elementId: TBD
name: mibObjectValueGauge
dataType: unsigned32
status: current
description: An IPFIX Information Element which denotes that the
Gauge value of a MIB object will be exported. The
MIB Object Identifier ("mibObjectIdentifier") for
this field MUST be exported in a MIB Field Option
or via another means. This Information Element is
used for MIB objects with the Base Syntax of Gauge32.
The value is encoded as per the standard IPFIX
Abstract Data Type of unsigned64. This value will
represent a non-negative integer, which may increase
or decrease, but shall never exceed a maximum
value, nor fall below a minimum value.
elementId: TBD
name: mibObjectValueTimeTicks
dataType: unsigned32
status: current
description: An IPFIX Information Element which denotes that the
TimeTicks value of a MIB object will be exported.
The MIB Object Identifier ("mibObjectIdentifier")
for this field MUST be exported in a MIB Field
Option or via another means. This Information
Element is used for MIB objects with the Base
Syntax of TimeTicks. The value is encoded as per
the standard IPFIX Abstract Data Type of unsigned32.
elementId: TBD
name: mibObjectValueUnsigned
dataType: unsigned64
status: current
description: An IPFIX Information Element which denotes that an
unsigned integer value of a MIB object will be
exported. The MIB Object Identifier
("mibObjectIdentifier") for this field MUST be
exported in a MIB Field Option or via another means.
This Information Element is used for MIB objects
with the Base Syntax of unsigned64 with IPFIX
Reduced Size Encoding used as required. The value is
encoded as per the standard IPFIX Abstract Data Type
of unsigned64.
elementId: TBD
name: mibObjectValueTable
dataType: orderedList
status: current
description: An IPFIX Information Element which denotes that a
complete or partial conceptual table will be
exported. The MIB Object Identifier
("mibObjectIdentifier") for this field MUST be
exported in a MIB Field Option or via another means.
This Information Element is used for MIB objects
with a SYNTAX of SEQUENCE. This is encoded as a
subTemplateList of mibObjectValue Information
Elements. The template specified in the
subTemplateList MUST be an Options Template and
MUST include all the Objects listed in the INDEX
clause as Scope Fields.
elementId: TBD
name: mibObjectValueRow
dataType: orderedList
status: current
description: An IPFIX Information Element which denotes that a
single row of a conceptual table will be exported.
The MIB Object Identifier ("mibObjectIdentifier")
for this field MUST be exported in a MIB Field
Option or via another means. This Information
Element is used for MIB objects with a SYNTAX of
SEQUENCE. This is encoded as a subTemplateList of
mibObjectValue Information Elements. The
subTemplateList exported MUST contain exactly one
row (i.e., one instance of the subtemplate). The
template specified in the subTemplateList MUST be
an Options Template and MUST include all the
Objects listed in the INDEX clause as Scope Fields.
elementId: TBD
name: mibObjectIdentifier
dataType: octetArray
status: current
description: An IPFIX Information Element which denotes that a
MIB Object Identifier (MIB OID) is exported in the
(Options) Template Record. The mibObjectIdentifier
Information Element contains the OID assigned to
the MIB Object Type Definition encoded as
ASN.1/BER [BER].
elementId: TBD
name: mibSubIdentifier
dataType: unsigned32
status: current
description: A non-negative sub-identifier of an Object
Identifier (OID).
elementId: TBD
name: mibIndexIndicator
dataType: unsigned64
status: current
description: This set of bit fields is used for marking the
Information Elements of a Data Record that serve as
INDEX MIB objects for an indexed Columnar MIB
object. Each bit represents an Information Element
in the Data Record with the n-th bit representing
the n-th Information Element. A bit set to value 1
indicates that the corresponding Information Element
is an index of the Columnar Object represented by
the mibFieldValue. A bit set to value 0 indicates
that this is not the case.
If the Data Record contains more than 64
Information Elements, the corresponding Template
SHOULD be designed such that all INDEX
Fields are among the first 64 Information Elements,
because the mibIndexIndicator only contains 64 bits.
If the Data Record contains less than 64
Information Elements, then the extra bits in the
mibIndexIndicator for which no corresponding
Information Element exists MUST have the value 0,
and must be disregarded by the Collector. This
Information Element may be exported with
IPFIX Reduced Size Encoding.
elementId: TBD
name: mibCaptureTimeSemantics
dataType: unsigned8
status: current
description: Indicates when in the lifetime of the flow the MIB
value was retrieved from the MIB for a
mibObjectIdentifier. This is used to indicate if
the value exported was collected from the MIB
closer to flow creation or flow export time and
will refer to the Timestamp fields included in the
same record. This field SHOULD be used when
exporting a mibObjectValue that specifies counters
or statistics.
If the MIB value was sampled by SNMP prior to the
IPFIX Metering Process or Exporting Process
retrieving the value (i.e., the data is already
stale) and it's important to know the exact sampling
time, then an additional observationTime* element
should be paired with the OID using structured data.
Similarly, if different mibCaptureTimeSemantics
apply to different mibObject elements within the
Data Record, then individual mibCaptureTimeSemantics
should be paired with each OID using structured data.
Values:
0. undefined
1. begin - The value for the MIB object is captured
from the MIB when the Flow is first observed
2. end - The value for the MIB object is captured
from the MIB when the Flow ends
3. export - The value for the MIB object is
captured from the MIB at export time
4. average - The value for the MIB object is an
average of multiple captures from the MIB over the
observed life of the Flow
elementId: TBD
name: mibContextEngineID
dataType: octetArray
status: current
description: A mibContextEngineID that specifies the SNMP engine
ID for a MIB field being exported over IPFIX.
Definition as per [RFC3411] section 3.3.
elementId: TBD
name: mibContextName
dataType: string
status: current
description: This Information Element denotes that a MIB Context
Name is specified for a MIB field being exported
over IPFIX. Reference [RFC3411] section 3.3.
elementId: TBD
name: mibObjectName
dataType: string
status: current
description: The name (called a descriptor in [RFC2578]
of an object type definition.
elementId: TBD
name: mibObjectDescription
dataType: string
status: current
description: The value of the DESCRIPTION clause of an MIB object
type definition.
elementId: TBD
name: mibObjectSyntax
dataType: string
status: current
description: The value of the SYNTAX clause of an MIB object type
definition, which may include a Textual Convention
or Subtyping. See [RFC2578].
elementId: TBD
name: mibModuleName
dataType: string
status: current
description: The textual name of the MIB module that defines a MIB
Object.
TODO: this section needs to refer out to wherever the operations / generalized workflow content ends up
TODO: revise to eliminate graph references
This section illustrates the proposed SACM Information Model as applied to SACM Usage Scenario 2.2.3, Detection of Posture Deviations [RFC7632]. The following subsections describe the elements (components and elements), graph model, and operations (sample workflow) required to support the Detection of Posture Deviations scenario.
The Detection of Posture Deviations scenario involves multiple elements interacting to accomplish the goals of the scenario. Figure 11 illustrates those elements along with their major communication paths.
The following subsections contain examples of identifiers and metadata which would enable detection of posture deviation. These lists are by no means exhaustive - many other types of metadata would be enumerated in a data model that fully addressed this usage scenario.
The proposed SACM Information Model contains three components, as defined in the SACM Architecture [I-D.ietf-sacm-architecture]: Posture Attribute Information Provider, Posture Attribute Information Consumer, and Control Plane.
In this example, the components are instantiated as follows:
To represent the elements listed above, the set of identifiers might include (but is not limited to):
To characterize the elements listed above, the set of metadata types might include (but is not limited to):
Interaction between multiple sets of identifiers and metadata lead to some fairly common patterns, or "constellations", of metadata. For example, an authenticated-session metadata constellation might include a central network session with authorizations and location attached, and links to a user identity, an endpoint identity, a MAC address, an IP address, and the identity of the policy server that authorized the session, for the duration of the network session.
These constellations may be independent of each other, or one constellation may be connected to another. For example, an authenticated-session metadata constellation may be created when a user connects an endpoint to the network; separately, an endpoint- posture metadata constellation may be created when an endpoint security system and other collectors gather and publish posture information related to an endpoint. These two constellations are not necessarily connected to each other, but may be joined if the component publishing the authenticated-session metadata constellation is able to link the network session identifier to the identity identifier of the endpoint.
The workflow for exchange of information supporting detection of posture deviation, using a standard publish/subscribe/query transport model such as available with IF-MAP [TNC-IF-MAP-SOAP-Binding] or XMPP-Grid [I-D.salowey-sacm-xmpp-grid], is as follows:
Other components, such as access control policy servers or remediation systems, may also consume the posture deviation information provided by the endpoint security service.
Many of the specifications in this document have been developed in a public-private partnership with vendors and end-users. The hard work of the SCAP community is appreciated in advancing these efforts to their current level of adoption.
Over the course of developing the initial draft, Brant Cheikes, Matt Hansbury, Daniel Haynes, Scott Pope, Charles Schmidt, and Steve Venema have contributed text to many sections of this document.
The RFC guidelines no longer allow RFCs to be published with a large number of authors. Some additional authors contributed to specific sections of this document; their names are listed in the individual section headings as well as alphabetically listed with their affiliations below.
| Name | Affiliation | Contact |
|---|---|---|
| Henk Birkholz | Fraunhofer SIT | henk.birkholz@sit.fraunhofer.de |
This memo includes no request to IANA.
TODO: Need to include various operational considerations here. Proposed sections include timestamp accuracy and which attributes attributes designate an endpoint.
TODO: Need to include various privacy considerations here.
Posture Assessments need to be performed in a safe and secure manner. In that regard, there are multiple aspects of security that apply to the communications between components as well as the capabilities themselves. Due to time constraints, this information model only contains an initial listing of items that need to be considered with respect to security. This list is not exhaustive, and will need to be augmented as the model continues to be developed/refined.
Initial list of security considerations include:
The TNC IF-MAP Binding for SOAP [TNC-IF-MAP-SOAP-Binding] and TNC IF-MAP Metadata for Network Security [TNC-IF-MAP-NETSEC-METADATA] document security considerations for sharing information via security automation. Most, and possibly all, of these considerations also apply to information shared via this proposed information model.
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC5280] | Cooper, D., Santesson, S., Farrell, S., Boeyen, S., Housley, R. and W. Polk, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008. |
Renamed "credential" to "identity", following industry usage. A credential includes proof, such as a key or password. A username or a distinguished name is called an "identity".
Removed Session, because an endpoint's network activity is not SACM's initial focus
Removed Authorization, for the same reason
Added many-to-many relationship between Hardware Component and Endpoint, for clarity
Added many-to-many relationship between Software Component and Endpoint, for clarity
Added "contains" relationship between Network Interface and Network Interface
Removed relationship between Network Interface and Account. The endpoint knows the identity it used to gain network access. The PDP also knows that. But they probably do not know the account.
Added relationship between Network Interface and Identity. The endpoint and the PDP will typically know the identity.
Made identity-to-account a many-to-one relationship.
Added Section Identifying Attributes.
Split the figure into Figure Model of Endpoint and Figure Information Elements.
Added Figure Information Elements Take 2, proposing a triple-store model.
Some editorial cleanup
Moved Appendix A.1, Appendix A.2, and Mapping to SACM Use Cases into the Appendix. Added a reference to it in Section 1
Added the Section 4 section. Provided notes for the type of information we need to add in this section.
Added the Section 6 section. Moved sections on Endpoint, Hardware Component, Software Component, Hardware Instance, and Software Instance there. Provided notes for the type of information we need to add in this section.
Removed the Provenance of Information Section. SACM is not going to solve provenance rather give organizations enough information to figure it out.
Updated references to the Endpoint Security Posture Assessment: Enterprise Use Cases document to reflect that it was published as an RFC.
Fixed the formatting of a few figures.
Included references to [RFC3580] where RADIUS is mentioned.
Integrated the IPFIX [RFC7012] syntax into Section 4.
Converted many of the existing SACM Information Elements to the IPFIX syntax.
Included existing IPFIX Information Elements and datatypes that could likely be reused for SACM in Section 7 and Section 4 respectively.
Removed the sections related to reports as described in https://github.com/sacmwg/draft-ietf-sacm-information-model/issues/30.
Cleaned up other text throughout the document.
Merged proposed changes from the I-D IM into the WG IM (https://github.com/sacmwg/draft-ietf-sacm-information-model/issues/41).
Fixed some formatting warnings.
Removed a duplicate IE and added a few IE datatypes that were missing.
Clarified that the SACM statement and content-element subjects are conceptual and that they do not need to be explicitly defined in a data model as long as the necessary information is provided.
Updated the IPFIX syntax used to define Information Elements. There are still a couple of open issues that need to be resolved.
Updated some of the Information Elements contained in Section 7 to use the revised IPFIX syntax. The rest of the Information Elements will be converted in a later revision.
Performed various clean-up and refactoring in Sections 6 and 7. Still need to go through Section 8.
Removed appendices that were not referenced in the body of the draft. The text from them is still available in previous revisions of this document if needed.