Internet Engineering Task Force (IETF)                       K. Moriarty
Request for Comments: 6046                                           EMC
Category: Informational                                      B. Trammell
ISSN: 2070-1721                                               ETH Zurich
                                                           November 2010


      Transport of Real-time Inter-network Defense (RID) Messages

Abstract

   The Incident Object Description Exchange Format (IODEF) defines a
   common XML format for document exchange, and Real-time Inter-network
   Defense (RID) defines extensions to IODEF intended for the
   cooperative handling of security incidents within consortia of
   network operators and enterprises.  This document specifies a
   transport protocol for RID based upon the passing of RID messages
   over HTTP/TLS (Transport Layer Security).

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6046.

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1.  Introduction

   The Incident Object Description Exchange Format (IODEF) [RFC5070]
   describes an XML document format for the purpose of exchanging data
   between Computer Security Incident Response Teams (CSIRTs) or those
   responsible for security incident handling for network providers
   (NPs).  The defined document format provides an easy way for CSIRTs
   to exchange data in a way that can be easily parsed.

   IODEF defines a message format, not a transport protocol, as the
   sharing of messages is assumed to be out of scope in order to allow
   CSIRTs to exchange and store messages in a way most suited to their
   established incident handling processes.  However, Real-time
   Inter-network Defense (RID) [RFC6045] does require a specification of
   a transport protocol to ensure interoperability among members in a
   RID consortium.  This document specifies the transport of RID
   messages within HTTP [RFC2616] Request and Response messages
   transported over Transport Layer Security (TLS) [RFC5246] (herein,
   HTTP/TLS).  Note that any IODEF message may also be transported using
   this mechanism, by sending it as a RID Report message.

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].

3.  Transmission of RID Messages over HTTP/TLS

   This section specifies the details of the transport of RID messages
   over HTTP/TLS.  In this arrangement, each RID server is both an HTTP/
   TLS server and an HTTP/TLS client.  When a RID message must be sent,
   the sending RID system connects to the receiving RID system and sends

   the message, optionally receiving a message in reply.  All RID
   systems MUST be prepared to accept HTTP/TLS connections from any RID
   peer with which it communicates, in order to support callback for
   delayed replies (see below).

   BCP 56 [RFC3205] contains a number of important considerations when
   using HTTP for application protocols.  These include the size of the
   payload for the application, whether the application will use a web
   browser, whether the protocol should be defined on a port other than
   80, and if the security provided through HTTP/TLS suits the needs of
   the new application.

   It is acknowledged within the scope of these concerns that HTTP/TLS
   is not ideally suited for RID transport, as the former is a client-
   server protocol and the latter a message-exchange protocol; however,
   the ease of implementation of RID systems over HTTP/TLS outweighs
   these concerns.  Consistent with BCP 56, RID systems will listen for
   TCP connections on port 4590.  Every RID system participating in a
   consortium MUST listen for HTTP/TLS connections on the assigned port.

   All RID messages sent in HTTP Requests MUST be sent using the POST
   with a Request-URI of "/"; additional Request-URI paths are reserved
   for future use by RID.

   Table 1 lists the allowable RID message types in an HTTP Response for
   a given RID message type in the Request.  A RID system MUST be
   prepared to handle an HTTP Response of the given type(s) when sending
   the corresponding HTTP Request.  A RID system MUST NOT send an HTTP
   Response containing any RID message other than the one corresponding
   to the one sent in the HTTP Request.

   As the queries and replies in a RID message exchange may be
   significantly separated in time, the receiving RID system MAY return
   202 Accepted, terminate the connection, and at a later time connect
   to the requesting RID system and send the RID reply in an HTTP
   Request.  This mechanism is referred to in this document as "RID
   callback".  When performing RID callback, a responding system MUST
   connect to the network- and transport-layer addresses from which the
   original request was sent; there is no mechanism in RID for
   redirected callback.

   While a RID system SHOULD return the reply in an HTTP Response if it
   is available immediately or within a generally accepted HTTP client
   timeout (about thirty seconds), this is not mandatory, and as such

   RID systems MUST be prepared for a query to be met with a 202
   Accepted, an empty Response body, a connection termination, and a
   callback.  Note that all RID messages require a response from the
   receiving RID system, so a sending RID system can expect either an
   immediate response or a callback.

   RID systems accepting a callback message in an HTTP Request MUST
   return 202 Accepted.

   Table 1 lists the allowable request/response pairs for RID.

    +----------------------+----------+--------+----------------------+
    | Request RID type     | Callback | Result | Response RID type    |
    +----------------------+----------+--------+----------------------+
    | TraceRequest         |          | 200    | RequestAuthorization |
    | TraceRequest         |          | 200    | Result               |
    | TraceRequest         |          | 202    | [empty]              |
    | RequestAuthorization |     X    | 202    | [empty]              |
    | Result               |     X    | 202    | [empty]              |
    | Investigation        |          | 200    | Result               |
    | Investigation        |          | 202    | [empty]              |
    | Report               |     X    | 202    | [empty]              |
    | IncidentQuery        |          | 200    | Report               |
    | IncidentQuery        |          | 202    | [empty]              |
    +----------------------+----------+--------+----------------------+

                                  Table 1

   For security purposes, RID systems SHOULD NOT return 3xx Redirection
   response codes, and MUST NOT follow any 3xx Redirection.  When a RID
   system's address changes, contact point information within the
   consortium must be updated out of band.

   If a RID system receives an improper RID message in an HTTP Request,
   it MUST return an appropriate 4xx Client Error result code to the
   requesting RID system.  If a RID system cannot process a RID message
   received in an HTTP Request due to an error on its own side, it MUST
   return an appropriate 5xx Server Error result code to the requesting
   RID system.

   Note that HTTP provides no mechanism for signaling to a server that a
   response body is not a valid RID message.  If a RID system receives
   an improper RID message in an HTTP Response, or cannot process a RID
   message received in an HTTP Response due to an error on its own side,
   it MUST log the error and present it to the RID system administrator
   for handling; the error logging format is an implementation detail
   and is considered out of scope for this specification.

   RID systems MUST support and SHOULD use HTTP/1.1 persistent
   connections as described in [RFC2616].  RID systems MUST support
   chunked transfer encoding on the HTTP server side to allow the
   implementation of clients that do not need to precalculate message
   sizes before constructing HTTP headers.

   RID systems MUST use TLS for confidentiality, identification, and
   strong mutual authentication as in [RFC2818]; see Section 4 below for
   details.

4.  Security Considerations

   All security considerations of related documents MUST be considered,
   especially the Incident Object Description Exchange Format (IODEF)
   [RFC5070] and Real-time Inter-network Defense (RID) [RFC6045].  The
   transport described herein is built on the foundation of these
   documents; the security considerations contained therein are
   incorporated by reference.

   For transport confidentiality, identification, and authentication,
   TLS with mutual authentication MUST be used to secure the HTTP
   connection as in [RFC2818].  The session MUST use non-NULL
   ciphersuites for authentication, integrity, and confidentiality;
   sessions MAY be renegotiated within these constraints.  Although TLS
   implementations typically support the older Secure Socket Layer (SSL)
   protocol, a RID peer MUST NOT request, offer, or use SSL 2.0, due to
   known security vulnerabilities in this protocol; see Appendix E of
   [RFC5246] for more.

   Each RID consortium SHOULD use a trusted public key infrastructure
   (PKI) to manage identities for RID systems participating in TLS
   connections.  At minimum, each RID system MUST trust a set of X.509
   Issuer identities ("Certificate Authorities") [RFC5280] to directly
   authenticate RID system peers with which it is willing to exchange
   information, and/or a specific white list of X.509 Subject identities
   of RID system peers.

   RID systems MUST provide for the verification of the identity of a
   RID system peer presenting a valid and trusted certificate, by
   verifying the fully qualified domain name or other network-layer
   identifier against that stored in the certificate, if available.
   More information on best practices in peer identity verification is
   available in [TLS-SERVER-ID].

5.  IANA Considerations

   Consistent with BCP 56 [RFC3205], since RID over HTTP/TLS is a
   substantially new service, and should be controlled at the consortium
   member network's border differently than HTTP/TLS, it requires a new
   port number.  IANA has assigned port 4590/tcp to RID with the service
   name RID over HTTP/TLS.

6.  References

6.1.  Normative References

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

   [RFC2616]   Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
               Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
               Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC2818]   Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.

   [RFC5070]   Danyliw, R., Meijer, J., and Y. Demchenko, "The Incident
               Object Description Exchange Format", RFC 5070,
               December 2007.

   [RFC5246]   Dierks, T. and E. Rescorla, "The Transport Layer Security
               (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [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, May 2008.

   [RFC6045]   Moriarty, K., "Real-time Inter-network Defense (RID)",
               RFC 6045, November 2010.

6.2.  Informative References

   [RFC3205]   Moore, K., "On the use of HTTP as a Substrate", BCP 56,
               RFC 3205, February 2002.

   [TLS-SERVER-ID]
               Saint-Andre, P. and J. Hodges, "Representation and
               Verification of Domain-Based Application Service Identity
               within Internet Public Key Infrastructure Using X.509
               (PKIX) Certificates in the Context of Transport Layer
               Security (TLS)", Work in Progress, October 2010.

Authors' Addresses

   Kathleen M. Moriarty
   RSA, The Security Division of EMC
   174 Middlesex Turnpike
   Bedford, MA  01730
   US

   EMail: Moriarty_Kathleen@EMC.com


   Brian H. Trammell
   Swiss Federal Institute of Technology Zurich
   Gloriastrasse 35
   8092 Zurich
   Switzerland

   Phone: +41 44 632 70 13
   EMail: trammell@tik.ee.ethz.ch