MILE Working Group J. Field
Internet-Draft Pivotal
Intended status: Informational S. Banghart
Expires: May 4, 2017 D. Waltermire
NIST
October 31, 2016
Resource-Oriented Lightweight Information Exchange
draft-ietf-mile-rolie-05
Abstract
This document defines a resource-oriented approach for security
automation information publication, discovery, and sharing. Using
this approach, producers may publish, share, and exchange
representations of security incidents, attack indicators, software
vulnerabilities, configuration checklists, and other security
automation information as Web-addressable resources. Furthermore,
consumers and other stakeholders may access and search this security
information as needed, establishing a rapid and on-demand information
exchange network for restricted internal use or public access
repositories. This specification extends the Atom Publishing
Protocol and Atom Syndication Format to transport and share security
automation resource representations.
Contributing to this document
The source for this draft is being maintained on GitHub. Suggested
changes should be submitted as pull requests at
<https://github.com/CISecurity/ROLIE>. Instructions are on that page
as well. Editorial changes can be managed in GitHub, but any
substantial issues need to be discussed on the MILE mailing list.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
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."
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This Internet-Draft will expire on May 4, 2017.
Copyright Notice
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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. XML-related Conventions . . . . . . . . . . . . . . . . . . . 4
3.1. XML Namespaces . . . . . . . . . . . . . . . . . . . . . 4
3.2. RELAX NG Compact Schema . . . . . . . . . . . . . . . . . 5
4. Background and Motivation . . . . . . . . . . . . . . . . . . 5
4.1. Proactive Sharing . . . . . . . . . . . . . . . . . . . . 5
4.2. Knowledge Aggregation . . . . . . . . . . . . . . . . . . 6
4.3. Resource-oriented Architecture . . . . . . . . . . . . . 6
5. ROLIE Requirements for the Atom Publishing Protocol . . . . . 7
5.1. AtomPub Service Documents . . . . . . . . . . . . . . . . 7
5.1.1. Use of the "app:workspace" Element . . . . . . . . . 8
5.1.2. Use of the "app:collection" Element . . . . . . . . . 8
5.1.3. Service Discovery . . . . . . . . . . . . . . . . . . 9
5.2. AtomPub Category Documents . . . . . . . . . . . . . . . 10
5.3. Transport Layer Security . . . . . . . . . . . . . . . . 10
5.4. User Authentication and Authorization . . . . . . . . . . 11
5.5. / (forward slash) Resource URL . . . . . . . . . . . . . 11
5.6. HTTP methods . . . . . . . . . . . . . . . . . . . . . . 12
6. ROLIE Requirements for the Atom Syndication Format . . . . . 12
6.1. Use of the "atom:feed" element . . . . . . . . . . . . . 12
6.1.1. Use of the "atom:category" Element . . . . . . . . . 13
6.1.2. Use of the "atom:link" Element . . . . . . . . . . . 14
6.1.3. Use of the "atom:updated" Element . . . . . . . . . . 15
6.2. Use of the "atom:entry" Element . . . . . . . . . . . . 15
6.2.1. Use of the "atom:content" Element . . . . . . . . . . 16
6.2.2. Use of the "atom:link" Element . . . . . . . . . . . 16
6.2.3. Use of the "rolie:format" Element . . . . . . . . . . 17
6.2.4. Requirements for a Standalone Entry . . . . . . . . . 18
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7. Available Extension Points Provided by ROLIE . . . . . . . . 18
7.1. The Category Extension Point . . . . . . . . . . . . . . 18
7.1.1. General Use of the "atom:category" Element . . . . . 19
7.1.2. Identification of Security Automation Information
Types . . . . . . . . . . . . . . . . . . . . . . . . 19
7.2. The "rolie:format" Extension Point . . . . . . . . . . . 21
7.3. The Link Relation Extension Point . . . . . . . . . . . . 21
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
8.1. XML Namespaces and Schema URNs . . . . . . . . . . . . . 21
8.2. ROLIE URN Sub-namespace . . . . . . . . . . . . . . . . . 22
8.3. ROLIE URN Parameters . . . . . . . . . . . . . . . . . . 22
8.4. ROLIE Security Resource Information Type Sub-Registry . . 23
9. Security Considerations . . . . . . . . . . . . . . . . . . . 24
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 26
11.1. Normative References . . . . . . . . . . . . . . . . . . 26
11.2. Informative References . . . . . . . . . . . . . . . . . 28
11.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Appendix A. Relax NG Compact Schema for ROLIE . . . . . . . . . 29
Appendix B. Examples of Use . . . . . . . . . . . . . . . . . . 30
B.1. Service Discovery . . . . . . . . . . . . . . . . . . . . 30
B.2. Feed Retrieval . . . . . . . . . . . . . . . . . . . . . 33
B.3. Entry Retrieval . . . . . . . . . . . . . . . . . . . . . 35
Appendix C. Change History . . . . . . . . . . . . . . . . . . . 36
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 37
1. Introduction
This document defines a resource-oriented approach to security
automation information sharing that follows the REST (Architectural S
tyles and the Design of Network-based Software Architectures)
architectural style. In this approach, computer security resources
are maintained in web-accessible repositories structured as Atom
Syndication Format [RFC4287] Feeds. Representations of specific
types of security automation information are categorized and
organized into indexed Collections which may be requested by the
consumer. As the set of resource Collections are forward facing, the
consumer may search all available content for which they are
authorized to view, and request the information resources which are
desired. Through use of granular authentication and access controls,
only authorized consumers may be permitted the ability to read or
write to a given Feed. This approach is in contrast to, and meant to
improve on, the traditional point-to-point messaging system, in which
consumers must request individual pieces of information from a server
following a triggering event. The point-to-point approach creates a
closed system of information sharing that encourages duplication of
effort and hinders automated security systems.
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The goal of this document is to define a RESTful approach to security
information communication with two primary intents: 1) increasing
communication and sharing of incident reports, vulnerability
assessments, configuration checklists, and other security automation
information between providers and consumers; and 2) establishing a
standardized communication system to support automated computer
security systems.
In order to deal with the great variety in security automation
information types and associated resource representations, this
specification defines extension points that can be used to add
support for new information types and associated resource
representations by means of additional supplementary specification
documents. This primary document is resource representation
agnostic, and defines the core requirements of all implementations.
An overview of the extension system is provided in Section 7.Those
seeking to provide support for specific security automation
information types should refer to the specification for that domain
described by the IANA registry found in section 8.4.
2. Terminology
The key words "MUST," "MUST NOT," "REQUIRED," "SHALL," "SHALL NOT,"
"SHOULD," "SHOULD NOT," "RECOMMENDED," "MAY," and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
Definitions for some of the common computer security-related
terminology used in this document can be found in Section 2 of
[RFC5070].
The following terms are unqiue to this specification:
Information Type A class of security automation information, having
an associated data model, that is the subject of a security
process that can be automated. See section 7.1.2 for more
information.
Do we need other terms to be defined?
3. XML-related Conventions
3.1. XML Namespaces
This specification uses XML Namespaces [W3C.REC-xml-names-20091208]
to uniquely identify XML element names. It uses the following
namespace prefix mappings for the indicated namespace URI:
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"app" is used for the "http://www.w3.org/2007/app" namespace
defined in [RFC5023].
"atom" is used for the "http://www.w3.org/2005/Atom" namespace
defined in [RFC4287].
"rolie" is used for the "urn:ietf:params:xml:ns:rolie:1.0"
namespace defined in section 8.1 of this specification.
3.2. RELAX NG Compact Schema
Some sections of this specification are illustrated with fragments of
a non-normative RELAX NG Compact schema [relax-NG]. However, the
text of this specification provides the definition of conformance.
Schema for the "http://www.w3.org/2007/app" and
"http://www.w3.org/2005/Atom" namespaces appear in RFC5023 appendix B
[RFC5023] and RFC4287 appendix B [RFC4287] respectively.
4. Background and Motivation
Information sharing is one of the core components of automating
security processes. Vulnerabilities, configurations, software
identification, security incidents, and patching data are just a few
of the classes of information that are shared today to enable
effective security on a wide scale. However, as the scale of defense
broadens to sometimes global networks, and the inherent scaling
issues of human-in-the-loop sharing become apparent, the need for
automation and machine-to-machine communication becomes apparent.
4.1. Proactive Sharing
Existing approaches to computer security information sharing often
use message exchange patterns that are point-to-point. Sometimes,
information that may be useful to share with multiple peers is only
made available to peers after they have specifically requested it.
Unfortunately, a sharing peer may not know, a priori, what
information to request from another peer. Some existing systems
provide a mechanism for unsolicited information requests, however,
these reports are again sent point-to-point, and must be reviewed for
relevance and then prioritized for action by the recipient,
introducing additional latency.
In order to adequately combat evolving threats, computer security
information resource providers should be able to share selected
information proactively. Proactive sharing greatly aids knowledge
dissemination, and improves response times and usability by allowing
the consumer to choose which information is relevant to its needs.
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For example, a security analyst can benefit by having the ability to
search a comprehensive collection of attack indicators that have been
published by a government agency, or by another member of a sharing
consortium. The representation of each indicator may include links
to the related resources, enabling an appropriately authenticated and
authorized analyst to freely navigate the information space of
indicators, incidents, vulnerabilities, and other computer security
domain concepts as needed. In this way, an analyst can more
effectively utilize the super set of information made publicly
available.
4.2. Knowledge Aggregation
Additionally, there is value in maintaining a repository of knowledge
that can be queried by a new consumer, allowing this consumer to
identify and retrieve any information that is relevant to its needs.
In this way, the consumer can gain access to meaningful current and
historic information, catching up to the knowledge level of its
peers.
Consider the case of an automated endpoint management system
attempting to proactively prevent software flaws and mis-configured
software from compromising the security of the affected systems.
During its full network sweep, the endpoint monitoring system would
check each endpoint for outdated, vulnerable, and mis-configured
software. This system would benefit from having access to not only
the software vendor's list of vulnerabilities and configuration
baselines, but also similar information discovered by other security
researchers. An advanced system could even give back to this sharing
consortium by sharing any relevant information discovered.
These capabilities support a federated collection of information
repositories that can be queried and contributed to by an
organization, further supporting automated security solutions.
4.3. Resource-oriented Architecture
Applying the REST architectural style to the problem domain of
security information sharing involves exposing information of any
relevant type as simple Web-addressable resources. Each provider
maintains their own repository of data, with public and private
sections as needed. Any producer or consumer can then discover these
repositories, search for relevant Feeds, and pull information from
them. By using this approach, an organization can more quickly and
easily share relevant data representations with a much larger and
potentially more diverse constituency. A consumer may leverage
virtually any available HTTP user agent in order to make requests of
the service provider. This improved ease of use enables more rapid
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adoption and broader participation, thereby improving security for
everyone.
A key aspect of any RESTful Web service is the ability to provide
multiple resource representations. For example, clients may request
that a given resource representation be returned as XML, JSON, or in
some other format. In order to enable backwards-compatibility and
interoperability with existing implementations, the RESTful approach
allows the provider to make differing formats available proactively,
allowing the consumer to simply select the version that best suits
them.
Finally, an important principle of the REST architectural style is
the focus on hypermedia as the engine of application state (HATEOAS).
Rather than the server maintaining conversational state for each
client, the server will instead include a suitable set of hyperlinks
in the resource representation that is returned to the client. The
included hyperlinks provide the client with a specific set of
permitted state transitions. Using these links the client may
perform an operation, such as updating or deleting the resource
representation. The client may also be provided with hypertext links
that can be used to navigate to any related resource. For example,
the resource representation for an object may contain links to the
related resource(s). In this way, the server remains stateless with
respect to a series of client requests.
5. ROLIE Requirements for the Atom Publishing Protocol
This section describes a number of restrictions of and extensions to
the Atom Publishing Protocol (AtomPub) [RFC5023] that define the use
of that protocol in the context of a ROLIE-based solution. The
normative requirements in this section are generally oriented towards
client and server implementations. An understanding of the Atom
Publishing Protocol specification [RFC5023] is helpful to understand
the requirements in this section.
5.1. AtomPub Service Documents
As described in RFC5023 section 8 [RFC5023], a Service Document is an
XML-based document format that allows a client to dynamically
discover the Collections provided by a publisher. A Service Document
consists of one or more app:workspace elements that may each contain
a number of app:collection elements.
The general structure of a service document is as follows (from
RFC5023 section 4.2 [RFC5023]):
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Service
o- Workspace
| |
| o- Collection
| |
| o- IRI, categories, media types
|
o- Workspace
|
o- Collection
|
o- IRI, categories, media types
5.1.1. Use of the "app:workspace" Element
In AtomPub, a Workspace, represented by the "app:workspace" element,
describes a group of one or more Collections. Building on the
AtomPub concept of a Workspace, in ROLIE a Workspace represents an
aggregation of Collections pertaining to security automation
information resources. This specification does not impose any
restrictions on the number of Workspaces that may be in a Service
Document or the specific Collections to be provided within a given
Workspace.
The following restrictions are imposed on the use of the
app:workspace element in ROLIE:
o A ROLIE repository can host Collections containing both public and
private information entries. It is RECOMMENDED that public and
private Collections be segregated into different Workspaces. By
doing this, Workspaces that contain private information can be
ignored by clients or can be omitted from the Service Document
provided to a client that lacks the appropriate privilege to
access the set of Collections associated with the Workspace.
o Appropriate descriptions and naming conventions SHOULD be used to
indicate the intended audience of each workspace. This helps to
facilitate the selection of appropriate Workspaces by users.
5.1.2. Use of the "app:collection" Element
In AtomPub, a Collection in a Service Document, represented by the
"app:collection" element, provides metadata that can be used to point
to a specific Atom Feed that contains information Entries that may be
of interest to a client. The association between a Collection and a
Feed is provided by the "href" attribute of the app:collection
element. Building on the AtomPub concept of a Collection, in ROLIE a
Collection represents a pointer to a group of security automation
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information resources pertaining to a given type of security
automation information. Collections are represented as Atom Feeds as
per RFC 5023. Atom Feed specific requirements are defined in section
6.1.
The following restrictions are imposed on the use of the
app:collection element for ROLIE:
o The atom:category elements contained in the app:categories element
MUST be the same set of atom:categories used in the Atom Feed
resource indicated by the app:collection "href" attribute value.
This ensures that the category metadata associated with the
Collection is discoverable in both the Feed and the corresponding
Collection in the Service Document.
o An app:collection pertaining to a security automation information
resource Feed MUST contain an app:categories element that
minimally contains a single atom:category element with the
"scheme" attribute value of
"urn:ietf:params:rolie:category:information-type". This category
MUST have an appropriate "term" attribute value as defined in
section 7.1.1. This ensures that a given Collection corresponds
to a specific type of security automation information.
o Any app:collection element that does not contain a descendant
atom:category element with the "scheme" attribute value of
"urn:ietf:params:rolie:category:information-type" MUST be
considered a non-ROLIE Collection. This allows Collections
pertaining to security automation information to co-exist
alongside Collections of other non-ROLIE information within the
same AtomPub instance.
o The app:categories element in an app:collection MAY include
additional atom:category elements using a scheme other than
"urn:ietf:params:rolie:category:information-type". This allows
other category metadata to be included.
5.1.3. Service Discovery
This specification requires that an implementation MUST publish an
Atom Service Document that describes the set of security information
sharing Collections that are provided by the repository.
The Service Document SHOULD be discoverable via the organization's
Web home page or another well-known public resource. An example of
this can be found in appendix B.1.
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The Service Document SHOULD be located at the standardized location
"https://{host:port}/rolie/servicedocument", where {host:port} is the
authority portion of the URI. Dereferencing this URI MAY result in a
redirect based on a HTTP 3xx status code to direct the client to the
actual Service Document. This allows clients to have a well-known
location to find a ROLIE service document, while giving
implementations flexibility over how the service is deployed.
When deploying a Service Document for use by a closed consortium, the
service document MAY also be digitally signed and/or encrypted. For
example, consider XML Signature Syntax and Processing [xmldsig] and
XML Encryption Syntax and Processing. [xmlenc]
5.2. AtomPub Category Documents
As described in RFC5023 section 7 [RFC5023], a Category Document is
an XML-based document format that allows a client to dynamically
discover the Categories used within AtomPub Service Documents, and
Atom Syndication Feed and Entry documents provided by a publisher. A
Category Document consists of one or more app:categories elements
that may each contain a number of app:collection elements.
A ROLIE implementation MUST publish an Category Document that
describes the set of atom:category elements and associated terms used
within the implemented repository.
5.3. Transport Layer Security
ROLIE is intended to be handled with TLS. The following requirements
have been derived from [RFC7589].
The most recent published version of TLS MUST be supported, and any
mandatory-to-implement (MTI) cipher suites in that version MUST be
supported as well.
The server MUST support certificate-based client authentication. The
implementation MAY use any TLS cipher suite that supports mutual
authentication.
During the TLS negotiation, the client MUST carefully examine the
certificate presented by the server to determine if it meets the
client's expectations. Particularly, the client MUST check its
understanding of the server hostname against the server's identity as
presented in the server Certificate message, in order to prevent man-
in-the-middle attacks. Matching is performed according to the rules
laid out in the Security Considerations section of [RFC4642].
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If the match fails, the client MUST either ask for explicit user
confirmation or terminate the connection and indicate the server's
identity is suspect. Additionally, clients MUST verify the binding
between the identity of the servers to which they connect and the
public keys presented by those servers. Clients SHOULD implement the
algorithm in Section 6 of [RFC5280] for general certificate
validation, but MAY supplement that algorithm with other validation
methods that achieve equivalent levels of verification (such as
comparing the server certificate against a local store of already-
verified certificates and identity bindings). If the client has
external information as to the expected identity of the server, the
hostname check MAY be omitted.
The server MUST be capable of verifying the identity of the client
with certificate-based authentication according to local policy to
ensure that the incoming client request is legitimate before any
configuration or state data is sent to or received from the client.
5.4. User Authentication and Authorization
Implementations MUST support user authentication. User
authentication MAY be enabled for specific Feeds.
Servers participating in an information sharing consortium and
supporting interactive user logins by members of the consortium
SHOULD support client authentication via a federated identity scheme
(e.g., SAML 2.0).
This document does not mandate the use of any specific user
authorization mechanisms. However, service implementers SHOULD
provide appropriate authorization checking for all resource accesses,
including individual Atom Entries, Atom Feeds, and Atom Service
Documents.
5.5. / (forward slash) Resource URL
The "/" resource MAY be provided for compatibility with existing
deployments that are using Transport of Real-time Inter-network
Defense (RID) Messages over HTTP/TLS [RFC6546]. If the "/" resource
is supported the following behavior MUST be also supported:
o Consistent with RFC6546 errata, a client requesting a GET on "/"
SHOULD receive an HTTP status code 405 Method Not Allowed.
o An implementation MAY provide full support for [RFC6546] such that
a POST to "/" containing a recognized RID message is handled
correctly as a RID request. Alternatively, a client requesting a
POST to "/" MAY receive an HTTP status code 307 Temporary
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Redirect. In this case, the location header in the HTTP response
will provide the URL of the appropriate RID endpoint, and the
client may repeat the POST method at the indicated location.
If the "/" resource is unsupported, then a request for this resource
MUST provide a 404 HTTP status code.
5.6. HTTP methods
Clients MUST be capable of recognizing and processing any standard
HTTP status code, as defined in [RFC5023] Section 5.
6. ROLIE Requirements for the Atom Syndication Format
This section describes a number of restrictions of and extensions to
the Atom Syndication Format [RFC4287] that define the use of that
format in the context of a ROLIE-based solution. The normative
requirements in this section are generally oriented towards content
to be published to a ROLIE repository. An understanding of the Atom
Syndication Format specification [RFC4287] is helpful to understand
the requirements in this section.
6.1. Use of the "atom:feed" element
As described in RFC4287 section 4.1.1 [RFC4287], an Atom Feed is an
XML-based document format that describes a list of related
information items, also known as a Collection. Each Feed document,
represented using the atom:feed element, contains a collection of
zero or more related information items individually called a "Member
Entry" or "Entry".
When applied to the problem domain of security automation information
sharing, an Atom Feed may be used to represent any meaningful
collection of security automation information resources. Each Entry
in an atom:feed represents an individual resource (e.g., a specific
checklist , a software vulnerability record). Additional Feeds can
be used to represent other collections of security automation
resources.
The following Atom Feed definition represents a stricter definition
of the atom:feed element defined in RFC 4287 for use in a ROLIE Any
element not specified here inherits its definition and requirements
from [RFC4287].
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atomFeed =
element atom:feed {
atomCommonAttributes,
(atomAuthor*
& atomCategory+
& atomContributor*
& atomGenerator?
& atomIcon?
& atomId
& atomLink+
& atomLogo?
& atomRights?
& atomSubtitle?
& atomTitle
& atomUpdated
& extensionElement*),
atomEntry*
}
6.1.1. Use of the "atom:category" Element
An atom:feed can be categorized and can contain information from zero
or more categories. In Atom the naming scheme and the semantic
meaning of the terms used to identify an Atom category are
application-defined.
The following restrictions are imposed on the use of the
atom:category element when used in an atom:feed:
o An atom:feed element MUST minimally contain a single atom:category
element with the "scheme" attribute value of
"urn:ietf:params:rolie:category:information-type". This category
MUST have an appropriate "term" attribute value as defined in
section 7.1.1. This ensures that a given Feed corresponds to a
specific type of security automation information. All member
Entries in the Feed MUST represent security automation information
records of this information type.
o Any atom:feed element that does not contain a child atom:category
element with the "scheme" attribute value of
"urn:ietf:params:rolie:category:information-type" MUST NOT be
considered a ROLIE Collection. This allows Feeds pertaining to
security automation information to co-exist alongside Feeds of
other non-ROLIE information within the same AtomPub instance.
o An atom:feed may include additional atom:category elements using a
scheme other than "urn:ietf:params:rolie:category:information-
type". This allows other category metadata to be included.
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6.1.2. Use of the "atom:link" Element
Link relations defined by the atom:link element are used to represent
state transitions using a stateless approach. In Atom a type of link
relationship can be defined using the "rel" attribute.
A ROLIE atom:feed MUST contain one or more atom:link elements with
rel="service" and href attribute whose value is a IRI that points to
an Atom Service Document associated with the atom:feed. When a
client is presented with a Feed as its initial view into a
repository, a link with the service relationship provides a means to
discover additional security automation information. The "service"
link relationship is defined in the IANA Link Relations Registry [1].
An atom:feed can contain an arbitrary number of Entries. In some
cases, a complete Feed may consist of a large number of Entries.
Additionally, as new and updated Entries are ordered at the beginning
of a Feed, a client may only be interested in retrieving the first N
entries in a Feed to process only the Entries that have changed since
the last retrieval of the Feed. As a practical matter, a large set
of Entries will likely need to be divided into more manageable
portions. Based on RFC5005 section 3 [RFC5005], link elements SHOULD
be included in all Feeds to support paging using the following link
relation types:
o "first" - Indicates that the href attribute value of the link
identifies a resource IRI for the furthest preceding page of the
Feed.
o "last" - Indicates that the href attribute value of the link
identifies a resource IRI for the furthest following page of the
Feed.
o "previous" - Indicates that the href attribute value of the link
identifies a resource IRI for the immediately preceding page of
the Feed.
o "next" - Indicates that the href attribute value of the link
identifies a resource IRI for the immediately following page of
the Feed.
For example:
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<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
<id>b7f65304-b63b-4246-88e2-c104049c5fd7</id>
<title>Paged Feed</title>
<link rel="self" href="http://example.org/feedA?page=5"/>
<link rel="first" href="http://example.org/feedA?page=1"/>
<link rel="prev" href="http://example.org/feedA?page=4"/>
<link rel="next" href="http://example.org/feedA?page=6"/>
<link rel="last" href="http://example.org/feedA?page=10"/>
<updated>2012-05-04T18:13:51.0Z</updated>
<!-- remainder of feed elements -->
</feed>
Example Paged Feed
A reference to a historical Feed may need to be stable, and/or a Feed
may need to be divided into a series of defined epochs.
Implementations SHOULD support the mechanisms described in RFC5005
section 4 [RFC5005] to provide link-based state transitions for
maintaining archiving of Feeds.
An atom:feed MAY include additional link relationships not specified
in this document. If a client encounters an unknown link
relationship type, the client MUST ignore the unrecognized link and
continue processing as if the unrecognized link element did not
appear. The definition of new Link relations that provide additional
state transition extensions is discussed in section 7.3.
6.1.3. Use of the "atom:updated" Element
The atom:updated element MUST be populated with the current time at
the instant the Feed representation was last updated by adding,
updating, or deleting an Entry; or changing any metadata for the
Feed.
6.2. Use of the "atom:entry" Element
Each Entry in an Atom Feed, represented by the atom:entry element,
describes a single information record, format, and type combination.
The following atom:entry schema definition represents a stricter
representation of the atom:entry element defined in [RFC4287] for use
in a ROLIE-based Atom Feed.
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atomEntry =
element atom:entry {
atomCommonAttributes,
(atomAuthor*
& atomCategory*
& atomContent
& atomContributor*
& atomId
& atomLink*
& atomPublished?
& atomRights?
& atomSource?
& atomSummary?
& atomTitle
& atomUpdated
& rolieFormat
& extensionElement*)
}
6.2.1. Use of the "atom:content" Element
There MUST be exactly one atomContent element in the Entry. The
content element MUST adhere to this definition, which is a stricter
representation of the atom:content element defined in [RFC4287]:
atomContent =
element atom:content {
atomCommonAttributes,
attribute type { atomMediaType },
attribute src { atomUri },
empty
}
The type attribute MUST identify the serialization type of the
content, for example, application/xml or application/json. A
prefixed media type MAY be used to reflect a specific model used with
a given serialization approach (e.g., application/rdf+xml). The src
attribute MUST be an IRI that can be dereferenced to retrieve the
related content data.
6.2.2. Use of the "atom:link" Element
Link relations can be included in an atom:entry to represent state
transitions for the Entry.
If there is a need to provide the same information in different data
models and/or serialization formats, separate Entry instances can be
included in the same or a different Feed. Such an alternate content
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representation can be indicated using an atom:link having a rel
attribute with the value "alternate".
An atom:feed MAY include additional link relationships not specified
in this document. If a client encounters an unknown link
relationship type, the client MUST ignore the unrecognized link and
continue processing as if the unrecognized link element did not
appear. The definition of new Link relations that provide additional
state transition extensions is discussed in section 7.3.
6.2.3. Use of the "rolie:format" Element
As mentioned earlier, a key goal of this specification is to allow a
consumer to review a set of published security automation information
resources, and then identify and retrieve any resources of interest.
The format of the data is a key criteria to consider when deciding
what information to retrieve. For a given type of security
automation information, it is expected that a number of different
formats may be used to represent this information. To support this
use case, both the serialization format and the specific data model
expressed in that format must be known by the consumer.
The rolie:format element is used to describe the data model used to
express the information referenced in the atom:content element of an
atom:entry. It also allows a schema to be identified that can be
used when parsing the content to verify or better understand the
structure of the content.
There MUST be exactly one rolie:format element in an atom:entry. The
element MUST adhere to this definition:
rolieFormat =
element rolie:format {
atomCommonAttributes,
attribute ns { atomURI },
attribute version { text } ?,
attribute schema-location { atomURI } ?,
attribute schema-type { atomMediaType } ?,
empty
}
The rolie:format element MUST provide a "ns" attribute that
identifies the data model of the resource referenced by the
atom:content element. For example, the namespace used may be an XML
namespace URI, or an identifier that represents a serialized JSON
model. The URI used for the "ns" attribute value MUST be an absolute
or opaque URI. The resource identified by the URI need not be
resolvable.
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The rolie:format element MAY provide a "version" attribute that
identifies the version of the format used for the related
atom:content.
The rolie:format element MAY provide a "schema-location" element that
is a URI that identifies a schema resource that can be used to
validate the related atom:content.
The rolie:format element MAY provide a "schema-type" element, which
is a mime type identifying the format of the schema resource
identified by the "schema-location" attribute.
6.2.4. Requirements for a Standalone Entry
If an Entry is ever shared as a standalone resource, separate from
its containing Feed, then the following additional requirements
apply:
o The Entry MUST have a atom:link element with rel="collection" and
href="[IRI of the containing Collection]". This allows the Feed
or Feeds for which the Entry is a member to be discovered, along
with the related information the Feed may contain. In the case of
the Entry have multiple containing Feeds, the Entry MUST have one
atom:link for each related Feed.
o The Entry MUST declare the information type of the content
resource referenced by the Entry (see Section 7.1.2).
7. Available Extension Points Provided by ROLIE
This specification does not require particular information types or
data formats; rather, ROLIE is intended to be extended by additional
specifications that define the use of new categories and link
relations. The primary point of extension is through the definition
of new information type category terms. Additional specifications
can register new information type category terms with IANA that serve
as the main characterizing feature of a ROLIE Collection/Feed or
Resource/Entry. These additional specifications defining new
information type terms, can describe additional requirements for
including specific categories, link relations, as well as, use of
specific data formats supporting a given information type term.
7.1. The Category Extension Point
The atom:category element, defined in RFC 4287 section 4.2.2
[RFC4287], provides a mechanism to provide additional categorization
information for a content resource in ROLIE. The ability to define
new categories is one of the core extension points provided by Atom.
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A Category Document, defined in RFC 5023 section 7 [RFC5023],
provides a mechanism for an Atom repository to make discoverable the
atom:category terms and allowed values used by a given repository.
ROLIE further defines the use of the existing Atom extension category
mechanism by allowing ROLIE specific category extensions to be
registered with IANA, and additionally has assigned the
"urn:ietf:params:rolie:category:information-type" category scheme
that has special meaning for implementations of ROLIE. This allows
category scheme namespaces to be managed in a more consistent way,
allowing for greater interoperability between content producers and
consumers.
Use of the "atom:category" element is discussed in the following
subsections.
7.1.1. General Use of the "atom:category" Element
The atom:category element can be used for characterizing a ROLIE
Resource. As discussed earlier in this document, an atom:category
element has a "term" attribute that indicates the assigned category
value, and a "scheme" attribute that provides an identifier for the
category type. The "scheme" provides a means to describe how a set
of category terms should be used and provides a namespace that can be
used to differentiate terms provided by multiple organizations with
different semantic meaning.
To further differentiate category types used in ROLIE, an IANA sub-
registry has been established for ROLIE protocol parameters to
support the registration of new category "scheme" attribute values by
ROLIE extension specifications. Use of this extension point is
discussed in section 8.3.
7.1.2. Identification of Security Automation Information Types
A ROLIE specific extension point is provided through the
atom:category "scheme" value
"urn:ietf:params:rolie:category:information-type". This value is a
Uniform Resource Name (URN) [RFC2141] that is registered with IANA as
described in section 8.3. When used as the "scheme" attribute in
this way, the "term" attribute is expected to be a registered value
as defined in section Section 8.4. Through this mechanism a given
security automation information type can be used to:
1. identify that an "app:collection" element in a Service Document
points to an Atom Feed that contains Entries pertaining to a
specific type of security automation information (see section
5.1.2), or
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2. identify that an "atom:feed" element in an Atom Feed contains
Entries pertaining to a specific type of security automation
information (see section 6.1.1).
3. identify the information type of a standalone Resource (see
section 6.2.4).
For example, the notional security automation information type
"incident" would be identified as follows:
<atom:category
scheme="urn:ietf:params:rolie:category:information-type"
term="incident"/>
A security automation information type represents a class of
information that represents the same or similar information model
[RFC3444]. Notional examples of information types include:
indicator: Computing device- or network-related "observable features
and phenomenon that aid in the forensic or proactive detection of
malicious activity; and associated meta-data" (from
[I-D.ietf-mile-rfc5070-bis]).
incident: Information pertaining to and "derived analysis from
security incidents" (from [I-D.ietf-mile-rfc5070-bis]).
vulnerability reports: Information identifying and describing a
vulnerability in hardware or software.
configuration checklists: Content that can be used to assess the
configuration settings related to installed software.
software tags: Metadata used to identify and characterize
installable software.
This is a short list to inspire new engineering of information type
extensions that support the automation of security processes.
This document does not specific any information types. Instead,
information types in ROLIE are expected to be registered in extension
documents that describe one or more new information types. This
allows the information types used by ROLIE implementations to grow
over time to support new security automation use cases. These
extension documents may also enhance ROLIE Service, Category, Feed,
and Entry documents by defining link relations, other categories, and
Format data model extensions to address the representational needs of
these specific information types. New information types are added to
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ROLIE through registrations to the IANA ROLIE Security Resource
Information Type registry defined in section 8.4.
7.2. The "rolie:format" Extension Point
Security automation data pertaining to a given information type may
be expressed using a number of supported formats. As described in
section 6.2.3, the rolie:format element is used to describe the
specific data model used to represent the resource referenced by a
given "atom:entry". The structure provided by the rolie:format
element, provides a mechanism for extension within the atom:entry
model. ROLIE extensions MAY further restrict which data models are
allowed to be used for a given information type.
By declaring the data model used for a given Resource, a consumer can
choose to download or ignore the Resource, or look for alternate
formats. This saves the consumer from downloading and parsing
resources that the consumer is not interested in or resources
expressed in formats that are not supported by the consumer.
7.3. The Link Relation Extension Point
This document uses several link relations defined in the IANA Link
Relation Types registry [2]. Additional link relations can be
registered in this registry to allow new relationships to be
represented in ROLIE according to RFC 4287 section 4.2.7.2 [RFC4287].
Based on the preceding reference, if the link relation is too
specific or limited in the intended use, an absolute IRI can be used
in lieu of registering a new simple name with IANA.
8. IANA Considerations
This document has a number of IANA considerations described in the
following subsections.
8.1. XML Namespaces and Schema URNs
This document uses URNs to describe XML namespaces and XML schemas
conforming to a registry mechanism described in [RFC3688].
ROLIE XML Namespace The ROLIE namespace (rolie-1.0) has been
registered in the "ns" registry.
URI: urn:ietf:params:xml:ns:rolie-1.0
Registrant Contact: IESG
XML: None. Namespace URIs do not represent an XML specification.
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ROLIE XML Schema The ROLIE schema (rolie-1.0) has been registered in
the "schema" registry.
URI: urn:ietf:params:xml:schema:rolie-1.0
Registrant Contact: IESG
XML: See section A of this document.
8.2. ROLIE URN Sub-namespace
IANA has added an entry to the "IETF URN Sub-namespace for Registered
Protocol Parameter Identifiers" registry located at
<http://www.iana.org/assignments/params/params.xml#params-1> as per
RFC3553 [RFC3553].
The entry is as follows:
Registry name: rolie
Specification: This document
Repository: ROLIE URN Parameters. See Section 8.3 [TO BE REMOVED:
This registration should take place at the following location:
https://www.iana.org/assignments/rolie]
Index value: See Section 8.3
8.3. ROLIE URN Parameters
A new top-level registry has been created, entitled "Resource
Oriented Lightweight Information Exchange (ROLIE) Parameters". [TO
BE REMOVED: This registration should take place at the following
location: https://www.iana.org/assignments/rolie]
In this top-level registry, a sub-registry entitled "ROLIE URN
Parameters" has been created. Registration in this repository is via
the Specification Required policy [RFC5226]. Designated Expert
reviews should be routed through the MILE WG mailing list. Failing
this, the Designated Expert will be assigned by the IESG.
Each entry in this sub-registry must record the following fields:
Name: A URN segment that adheres to the pattern {type}:{label}.
The keywords are defined as follows:
{type}: The parameter type. The allowed value is "category".
"category" denotes a category extension as discussed in
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Section 7.1. While a single value is used in this
specification, future revisions or extensions of this
specification may define additional {type} values.
{label}: A required US-ASCII string that conforms to the URN
syntax requirements (see [RFC2141]). This string must be
unique within the namespace defined by the {type} keyword.
Extension IRI: The identifier to use within ROLIE, which is the
full URN using the form: urn:ietf:params:rolie:{name}, where
{name} is the "name" field of this registration.
Reference: A static link to the specification and section that the
definition of the parameter can be found.
Sub-registry: An optional field that links to an IANA sub-registry
for this parameter. If the {type} is "category", the sub-registry
must contain a "name" field whose registered values MUST be US-
ASCII. The list of names are the allowed values of the "term"
attribute in the atom:category element. (See Section 7.1.2).
This repository has the following initial values:
+-----------+--------------------+------+---------------------------+
| Name | Extension IRI | Refe | Sub-Registry |
| | | renc | |
| | | e | |
+-----------+--------------------+------+---------------------------+
| category: | urn:ietf:params:ro | This | [TO BE REMOVED: This |
| informati | lie:category | docu | registration should take |
| on-type | :information-type | ment | place at the following |
| | | , Se | location: https://www.ian |
| | | ctio | a.org/assignments/rolie/c |
| | | n | ategory/information-type] |
| | | 9.4 | |
+-----------+--------------------+------+---------------------------+
8.4. ROLIE Security Resource Information Type Sub-Registry
A new sub-registry has been created to store ROLIE information type
values.
Name of Registry: "ROLIE Information Types"
Location of Registry:
https://www.iana.org/assignments/rolie/category/information-type
Fields to record in the registry:
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name: The full name of the security resource information type
as a string from the printable ASCII character set [RFC0020]
with individual embedded spaces allowed. The ABNF [RFC5234]
syntax for this field is:
1*VCHAR *(SP 1*VCHAR)
index: This is an IANA-assigned positive integer that
identifies the registration. The first entry added to this
registry uses the value 1, and this value is incremented for
each subsequent entry added to the registry.
reference: A list of one or more URIs [RFC3986] from which the
registered specification can be obtained. The registered
specification MUST be readily and publicly available from that
URI. The URI SHOULD be a stable reference.
Allocation Policy: Specification required as per [RFC5226]
9. Security Considerations
This document defines a resource-oriented approach for lightweight
information exchange using HTTP over TLS, the Atom Syndication
Format, and the Atom Publishing Protocol. As such, implementers must
understand the security considerations described in those
specifications. All that follows is guidance, more specific
instruction is out of scope for this document and will be located in
a dedicated informational document.
All security measures SHOULD be enforced at the source, that is, a
provider SHOULD NOT return any Feed content or member Entry content
for which the client identity has not been specifically
authenticated, authorized, and audited.
The approach described herein is based upon all policy enforcements
being implemented at the point when a resource representation is
created. As such, producers sharing cyber security information using
this specification must take care to authenticate their HTTP clients
using a suitably strong user authentication mechanism. Sharing
communities that are exchanging information on well-known indicators
and incidents for purposes of public education may choose to rely
upon HTTP Authentication or similar. However, sharing communities
that are engaged in sensitive collaborative analysis and/or
operational response for indicators and incidents targeting high
value information systems should adopt a suitably stronger user
authentication solution, such as a risk-based or multi-factor
approach. In general, trust in the sharing consortium will depend
upon the members maintaining adequate user authentication mechanisms.
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Collaborating consortiums may benefit from the adoption of a
federated identity solution, such as those based upon SAML-core
[SAML-core], SAML-bind [SAML-bind], and SAML-prof [SAML-prof] for
Web-based authentication and cross-organizational single sign-on.
Dependency on a trusted third party identity provider implies that
appropriate care must be exercised to sufficiently secure the
Identity provider. Any attacks on the federated identity system
would present a risk to the CSIRT, as a relying party. Potential
mitigations include deployment of a federation-aware identity
provider that is under the control of the information sharing
consortium, with suitably stringent technical and management
controls.
Authorization of resource representations is the responsibility of
the source system, i.e. based on the authenticated user identity
associated with an HTTP(S) request. The required authorization
policies that are to be enforced must therefore be managed by the
security administrators of the source system. Various authorization
architectures would be suitable for this purpose, such as RBAC [3]
and/or ABAC, as embodied in XACML [XACML]. In particular,
implementers adopting XACML may benefit from the capability to
represent their authorization policies in a standardized,
interoperable format. Note that implementers are free to choose any
suitable authorization mechanism that is capable of fulfilling the
policy enforcement requirements relevant to their consortium and/or
organization.
Additional security requirements such as enforcing message-level
security at the destination system could supplement the security
enforcements performed at the source system, however these
destination-provided policy enforcements are out of scope for this
specification. Implementers requiring this capability should
consider leveraging, e.g. the <RIDPolicy> element in the RID schema.
Refer to RFC6545 section 9 for more information.
When security policies relevant to the source system are to be
enforced at both the source and destination systems, implementers
must take care to avoid unintended interactions of the separately
enforced policies. Potential risks will include unintended denial of
service and/or unintended information leakage. These problems may be
mitigated by avoiding any dependence upon enforcements performed at
the destination system. When distributed enforcement is unavoidable,
the usage of a standard language (e.g. XACML) for the expression of
authorization policies will enable the source and destination systems
to better coordinate and align their respective policy expressions.
Adoption of the information sharing approach described in this
document will enable users to more easily perform correlations across
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separate, and potentially unrelated, cyber security information
providers. A client may succeed in assembling a data set that would
not have been permitted within the context of the authorization
policies of either provider when considered individually. Thus,
providers may face a risk of an attacker obtaining an access that
constitutes an undetected separation of duties (SOD) violation. It
is important to note that this risk is not unique to this
specification, and a similar potential for abuse exists with any
other cyber security information sharing protocol. However, the wide
availability of tools for HTTP clients and Atom Feed handling implies
that the resources and technical skills required for a successful
exploit may be less than it was previously. This risk can be best
mitigated through appropriate vetting of the client at account
provisioning time. In addition, any increase in the risk of this
type of abuse should be offset by the corresponding increase in
effectiveness that this specification affords to the defenders.
10. Acknowledgements
The authors gratefully acknowledge the valuable contributions of Tom
Maguire, Kathleen Moriarty, and Vijayanand Bharadwaj. These
individuals provided detailed review comments on earlier drafts, and
made many suggestions that have helped to improve this document.
11. References
11.1. Normative References
[RFC0020] Cerf, V., "ASCII format for network interchange", STD 80,
RFC 20, DOI 10.17487/RFC0020, October 1969,
<http://www.rfc-editor.org/info/rfc20>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<http://www.rfc-editor.org/info/rfc3688>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>.
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[RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom
Syndication Format", RFC 4287, DOI 10.17487/RFC4287,
December 2005, <http://www.rfc-editor.org/info/rfc4287>.
[RFC5005] Nottingham, M., "Feed Paging and Archiving", RFC 5005,
DOI 10.17487/RFC5005, September 2007,
<http://www.rfc-editor.org/info/rfc5005>.
[RFC5023] Gregorio, J., Ed. and B. de hOra, Ed., "The Atom
Publishing Protocol", RFC 5023, DOI 10.17487/RFC5023,
October 2007, <http://www.rfc-editor.org/info/rfc5023>.
[RFC5070] Danyliw, R., Meijer, J., and Y. Demchenko, "The Incident
Object Description Exchange Format", RFC 5070,
DOI 10.17487/RFC5070, December 2007,
<http://www.rfc-editor.org/info/rfc5070>.
[RFC6546] Trammell, B., "Transport of Real-time Inter-network
Defense (RID) Messages over HTTP/TLS", RFC 6546,
DOI 10.17487/RFC6546, April 2012,
<http://www.rfc-editor.org/info/rfc6546>.
[RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An
IETF URN Sub-namespace for Registered Protocol
Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June
2003, <http://www.rfc-editor.org/info/rfc3553>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[W3C.REC-xml-names-20091208]
Bray, T., Hollander, D., Layman, A., Tobin, R., and H.
Thompson, "Namespaces in XML 1.0 (Third Edition)", World
Wide Web Consortium Recommendation REC-xml-names-20091208,
December 2009,
<http://www.w3.org/TR/2009/REC-xml-names-20091208>.
[RFC7589] Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the
NETCONF Protocol over Transport Layer Security (TLS) with
Mutual X.509 Authentication", RFC 7589,
DOI 10.17487/RFC7589, June 2015,
<http://www.rfc-editor.org/info/rfc7589>.
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[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,
<http://www.rfc-editor.org/info/rfc5280>.
[RFC4642] Murchison, K., Vinocur, J., and C. Newman, "Using
Transport Layer Security (TLS) with Network News Transfer
Protocol (NNTP)", RFC 4642, DOI 10.17487/RFC4642, October
2006, <http://www.rfc-editor.org/info/rfc4642>.
[relax-NG]
Clark, J., Ed., "RELAX NG Compact Syntax", 11 2002,
<https://www.oasis-open.org/committees/relax-ng/compact-
20021121.html>.
[SAML-core]
Cantor, S., Kemp, J., Philpott, R., and E. Maler,
"Assertions and Protocol for the OASIS Security Assertion
Markup Language (SAML) V2.0", OASIS Standard saml-core-
2.0-os, March 2005, <http://docs.oasis-
open.org/security/saml/v2.0/saml-core-2.0-os.pdf>.
[SAML-prof]
Hughes, J., Cantor, S., Hodges, J., Hirsch, F., Mishra,
P., Philpott, R., and E. Maler, "Profiles for the OASIS
Security Assertion Markup Language (SAML) V2.0", OASIS
Standard OASIS.saml-profiles-2.0-os, March 2005,
<http://docs.oasis-open.org/security/saml/v2.0/
saml-profiles-2.0-os.pdf>.
[SAML-bind]
Cantor, S., Hirsch, F., Kemp, J., Philpott, R., and E.
Maler, "Bindings for the OASIS Security Assertion Markup
Language (SAML) V2.0", OASIS Standard saml-bindings-
2.0-os, March 2005, <http://docs.oasis-
open.org/security/saml/v2.0/saml-bindings-2.0-os.pdf>.
11.2. Informative References
[RFC2141] Moats, R., "URN Syntax", RFC 2141, DOI 10.17487/RFC2141,
May 1997, <http://www.rfc-editor.org/info/rfc2141>.
[RFC3444] Pras, A. and J. Schoenwaelder, "On the Difference between
Information Models and Data Models", RFC 3444,
DOI 10.17487/RFC3444, January 2003,
<http://www.rfc-editor.org/info/rfc3444>.
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[I-D.ietf-mile-rfc5070-bis]
Danyliw, R., "The Incident Object Description Exchange
Format v2", draft-ietf-mile-rfc5070-bis-26 (work in
progress), October 2016.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<http://www.rfc-editor.org/info/rfc5234>.
[xmldsig] Bartel, M., Boyer, J., Fox, B., LaMacchia, B., and E.
Simon, "XML Signature Syntax and Processing (Second
Edition)", June 2008, <https://www.w3.org/TR/xmldsig-
core/>.
[xmlenc] Imamura, T., Dillaway, B., and E. Simon, "XML Encryption
Syntax and Processing", December 2002,
<https://www.w3.org/TR/xmlenc-core/>.
[XACML] Rissanen, E., "eXtensible Access Control Markup Language
(XACML) Version 3.0", August 2010, <http://docs.oasis-
open.org/xacml/3.0/xacml-3.0-core-spec-cs-01-en.pdf>.
[REST] Fielding, R., "Architectural Styles and the Design of
Network-based Software Architectures", 2000,
<http://www.ics.uci.edu/~fielding/pubs/dissertation/
top.htm>.
11.3. URIs
[1] https://www.iana.org/assignments/link-relations/link-
relations.xhtml
[2] https://www.iana.org/assignments/link-relations/link-
relations.xhtml
[3] http://csrc.nist.gov/groups/SNS/rbac/
Appendix A. Relax NG Compact Schema for ROLIE
This appendix is informative.
The Relax NG schema below defines the rolie:format element.
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# -*- rnc -*-
# RELAX NG Compact Syntax Grammar for the rolie:format element
namespace rolie = "urn:ietf:params:xml:ns:rolie-1.0"
namespace atom = "http://www.w3.org/2005/Atom"
# rolie:format
rolieFormat =
element rolie:format {
atom:atomCommonAttributes,
attribute ns { atom:atomURI },
attribute version { text } ?,
attribute schema-location { atom:atomURI } ?,
attribute schema-type { atom:atomMediaType } ?,
empty
}
Appendix B. Examples of Use
B.1. Service Discovery
This section provides a non-normative example of a client doing
service discovery.
An Atom service document enables a client to dynamically discover
what Feeds a particular publisher makes available. Thus, a provider
uses an Atom service document to enable clients or other authorized
parties to determine what specific information the provider makes
available to the community. While the service document is at a
required location, the service document could also be made available
at any well known location, such as via a link from the producer's
home page.
A client may format an HTTP GET request to retrieve the service
document from the specified location:
GET /rolie/servicedocument
Host: www.example.org
Accept: application/atomsvc+xml
Notice the use of the HTTP Accept: request header, indicating the
MIME type for Atom service discovery. The response to this GET
request will be an XML document that contains information on the
specific Feed Collections that are provided by the provider.
Example HTTP GET response:
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HTTP/1.1 200 OK
Date: Fri, 24 Aug 2012 17:09:11 GMT
Content-Length: 570
Content-Type: application/atomsvc+xml;charset="utf-8"
<?xml version="1.0" encoding="UTF-8"?>
<service xmlns="http://www.w3.org/2007/app"
xmlns:atom="http://www.w3.org/2005/Atom">
<workspace>
<atom:title type="text">Vulnerabilities</atom:title>
<collection href="http://example.org/provider/vulns">
<atom:title type="text">Vulnerabilities Feed</atom:title>
<categories fixed="yes">
<atom:category
scheme="urn:ietf:params:rolie:category:information-type"
term="vulnerability"/>
</categories>
</collection>
</workspace>
</service>
This simple Service Document example shows that this server provides
one workspace, named "Vunerabilities". Within that workspace, the
producer makes one Feed Collection available.
A server may also offer a number of different Feeds, each containing
different types of security automation information. In the following
example, the Feeds have been categorized. This categorization will
help the clients to decide which Feeds will meet their needs.
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HTTP/1.1 200 OK
Date: Fri, 24 Aug 2012 17:10:11 GMT
Content-Length: 1912
Content-Type: application/atomsvc+xml;charset="utf-8"
<?xml version="1.0" encoding='utf-8'?>
<service xmlns="http://www.w3.org/2007/app"
xmlns:atom="http://www.w3.org/2005/Atom">
<workspace>
<atom:title>Public Security Information Sharing</atom:title>
<collection
href="http://example.org/provider/public/vulns">
<atom:title>Public Vulnerabilities</atom:title>
<link rel="service"
href="www.example.com/rolie/servicedocument">
<categories fixed="yes">
<atom:category
scheme="urn:ietf:params:rolie:category:information-type"
term="vulnerability"/>
</categories>
</collection>
</workspace>
<workspace>
<atom:title>Private Consortium Sharing</atom:title>
<collection
href="http://example.org/provider/private/vulns">
<atom:title>Incidents</atom:title>
<link rel="service"
href="www.example.com/rolie/servicedocument">
<categories fixed="yes">
<atom:category
scheme="urn:ietf:params:rolie:category:information-type"
term="incidents"/>
</categories>
</collection>
</workspace>
</service>
In this example, the provider is making available a total of two Feed
Collections, organized into two different workspaces. The first
workspace contains a Feed consisting of publicly available software
vulnerabilities. The second workspace provides one additional
vulnerability Feed, for use by a private sharing consortium. An
appropriately authenticated and authorized client may then proceed to
make GET requests for one or more of these Feeds. The publicly
provided incident information may be accessible with or without
authentication. However, users accessing the Feed targeted to the
private sharing consortium would be expected to authenticate, and
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appropriate authorization policies would subsequently be enforced by
the Feed provider.
B.2. Feed Retrieval
This section provides a non-normative example of a client retrieving
an incident Feed.
Having discovered the available security information sharing Feeds, a
client who is a member of the general public may be interested in
receiving the Feed of public vulnerabilities. The client may
retrieve this Feed by performing an HTTP GET operation on the
indicated URL.
Example HTTP GET request for a Feed:
GET /provider/vulns
Host: www.example.org
Accept: application/atom+xml
The corresponding HTTP response would be an XML document containing
the incidents Feed:
Example HTTP GET response for a Feed:
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HTTP/1.1 200 OK
Date: Fri, 24 Aug 2012 17:20:11 GMT
Content-Length: 2882
Content-Type: application/atom+xml;type=feed;charset="utf-8"
<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom"
xml:lang="en-US">
<id>http://www.example.org/provider/vulns</id>
<title type="text">
Atom formatted representation of
a feed of XML incident documents
</title>
<atom:category
scheme="urn:ietf:params:rolie:category:information-type"
term="vulnerability"/>
<updated>2012-05-04T18:13:51.0Z</updated>
<link rel="self" href="http://example.org/provider/vulns" />
<link rel="service"
href="http://example.org/rolie/servicedocument"/>
<entry>
<rolie:format ns="urn:ietf:params:xml:ns:exampleformat"/>
<id>
http://www.example.org/provider/vulns/123456
</id>
<title>Sample Incident</title>
<published>2014-08-04T18:13:51.0Z</published>
<updated>2014-08-05T18:13:51.0Z</updated>
<summary>A short description of this resource</summary>
<content type="application/xml"
src="http://www.example.org/provider/vulns/123456/data"
</entry>
<entry>
<!-- ...another entry... -->
</entry>
</feed>
This Feed document has two atom entries, one of which has been
elided. The completed Entry illustrates an Atom <entry> element that
provides a summary of essential details about one particular
incident. Based upon this summary information and the provided
category information, a client may choose to do an HTTP GET operation
to retrieve the full details of the incident. This example
exemplifies the benefits a RESTful alternative has to traditional
point-to-point messaging systems.
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B.3. Entry Retrieval
This section provides a non-normative example of a client retrieving
an incident as an Atom Entry.
Having retrieved the Feed of interest, the client may then decide
based on the description and/or category information that one of the
entries in the Feed is of further interest. The client may retrieve
this incident Entry by performing an HTTP GET operation on the
indicated URL.
Example HTTP GET request for an Entry:
GET /provider/vulns/123456
Host: www.example.org
Accept: application/atom+xml
The corresponding HTTP response would be an XML document containing
the incident:
Example HTTP GET response for an Entry:
HTTP/1.1 200 OK
Date: Fri, 24 Aug 2012 17:30:11 GMT
Content-Length: 4965
Content-Type: application/atom+xml;type=entry;charset="utf-8"
<?xml version="1.0" encoding="UTF-8"?>
<entry>
<id>http://www.example.org/provider/vulns/123456</id>
<title>Sample Incident</title>
<published>2012-08-04T18:13:51.0Z</published>
<updated>2012-08-05T18:13:51.0Z</updated>
<atom:category
scheme="urn:ietf:params:rolie:category:information-type"
term="incident"/>
<summary>A short description of this incident resource</summary>
<rolie:format ns="urn:ietf:params:xml:ns:exampleformat"/>
<content type="application/xml"
src="http://www.example.org/provider/vulns/123456/data">
</content>
</entry>
As can be seen in the example response, above, an XML document is
linked to in the attributes of the Atom <content> element. The
client may now process the XML document as needed.
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Note also that, as described previously, the content of the Atom
<category> element is application-defined. The Atom categories have
been assigned based on the IANA table content model.
Finally, it should be noted that in order to optimize the client
experience, and avoid an additional round trip, a Feed provider may
choose to include certain Entry elements inline, as part of the Feed
document. That is, an Atom <entry> element within a Feed document
may contain arbitrary non-required Atom elements as children. In
this case, the client will receive the more explicit information on
entries from within the Feed. The decision of whether to include
extra Entry elements inline or to include it as a link is a design
choice left to the Feed provider (e.g. based upon local environmental
factors such as the number of entries contained in a Feed, the
available network bandwidth, the available server compute cycles, the
expected client usage patterns, etc.).
Appendix C. Change History
Changes in draft-ietf-mile-rolie-04 since draft-ietf-mile-rolie-04
version, July 8, 2016 to October 31, 2016
o Further specification and clarification of requirements
o IANA Considerations and extension system fleshed out and
described.
o Examples and References updated.
o Schema created.
o Fixed both internal section and external document referencing.
o Removed XACML Guidance Appendix. This will be added to a future
draft on ROLIE Authentication and Access Control.
Changes made in draft-ietf-mile-rolie-03 since draft-ietf-mile-
rolie-02 version, May 27, 2016 to July 8, 2015
o Atom Syndication and Atom Pub requirements split and greatly
expanded for increased justification and technical specification.
o Reintroduction and reformatting of some use case examples in order
to provide some guidance on use.
o Established rough version of IANA table extension system along
with explanations of said system.
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o Re-organized document to put non-vital information in appendices.
Changes made in draft-ietf-mile-rolie-02 since draft-field-mile-
rolie-01 version, December, 2015 to May 27, 2016:
o All CSIRT and IODEF/RID material moved to companion CSIRT document
TODO: add reference
o Recast document into a more general use perspective. The
implication of CSIRTs as the defacto end-user has been removed
where ever possible. All of the original CSIRT based use cases
remain completely supported by this document, it has been opened
up to support many other use cases.
o Changed the content model to broaden support of representation
o Edited and rewrote much of sections 1,2 and 3 in order to
accomplish a broader scope and greater readability
o Removed any requirements from the Background section and, if not
already stated, placed them in the requirements section
o Re-formatted the requirements section to make it clearer that it
contains the lions-share of the requirements of the specification
Changes made in draft-ietf-mile-rolie-01 since draft-field-mile-
rolie-02 version, August 15, 2013 to December 2, 2015:
o Added section specifying the use of RFC5005 for Archive and Paging
of Feeds.
o Added section describing use of atom categories that correspond to
IODEF expectation class and impact classes. See: normative-
expectation-impact
o Dropped references to adoption of a MILE-specific HTTP media type
parameter.
o Updated IANA Considerations section to clarify that no IANA
actions are required.
Authors' Addresses
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John P. Field
Pivotal Software, Inc.
625 Avenue of the Americas
New York, New York
USA
Phone: (646)792-5770
Email: jfield@pivotal.io
Stephen A. Banghart
National Institute of Standards and Technology
100 Bureau Drive
Gaithersburg, Maryland
USA
Phone: (301)975-4288
Email: sab3@nist.gov
David Waltermire
National Institute of Standards and Technology
100 Bureau Drive
Gaithersburg, Maryland 20877
USA
Email: david.waltermire@nist.gov
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