One document matched: draft-gont-6man-nd-extension-headers-01.txt
Differences from draft-gont-6man-nd-extension-headers-00.txt
IPv6 maintenance Working Group (6man) F. Gont
Internet-Draft UK CPNI
Updates: 4861 (if approved) June 8, 2011
Intended status: Standards Track
Expires: December 10, 2011
Security Implications of the Use of IPv6 Extension Headers with IPv6
Neighbor Discovery
draft-gont-6man-nd-extension-headers-01
Abstract
IPv6 Extension Headers with Neighbor Discovery messages can be
leveraged to circumvent simple local network protections, such as
"Router Advertisement Guard". Since there is no legitimate use for
IPv6 Extension Headers in Neighbor Discovery messages, and such use
greatly complicates network monitoring and simple security
mitigations such as RA-Guard, this document proposes that hosts
silently ignore Neighbor Discovery messages that use IPv6 Extension
Headers.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. This document may not be modified,
and derivative works of it may not be created, and it may not be
published except as an Internet-Draft.
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 10, 2011.
Copyright Notice
Copyright (c) 2011 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
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(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Specification . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1. Normative References . . . . . . . . . . . . . . . . . . . 7
5.2. Informative References . . . . . . . . . . . . . . . . . . 7
Appendix A. Changes from previous versions of the draft (to
be removed by the RFC Editor before publication
of this document as a RFC . . . . . . . . . . . . . . 8
A.1. Changes from draft-gont-6man-nd-extension-headers-00 . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Introduction
IPv6 Router Advertisement Guard (RA-Guard) is a mitigation technique
for attack vectors based on ICMPv6 Router Advertisement messages.
[RFC6104] describes the problem statement of "Rogue IPv6 Router
Advertisements", and [RFC6105] specifies the "IPv6 Router
Advertisement Guard" functionality.
[I-D.gont-v6ops-ra-guard-evasion] describes how IPv6 Extension
Headers can be leveraged to circumvent the RA-Guard protection.
Additionally, the use of Extension Headers (and of the Fragmentation
Header in particularly) greatly increases the difficulty to monitor
Neighbor Discovery traffic (e.g., with tools such as NDPMon
[NDPMon]).
Since there is no current legitimate use for IPv6 Extension Headers
in IPv6 Neighbor Discovery packets, and avoiding their use in such
packets would greatly simplify the monitoring and mitigation of
Neighbor Discovery attacks, this document proposes that hosts
silently ignore Neighbor Discovery messages that employ IPv6
Extension Headers.
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].
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2. Specification
Hosts SHOULD silently ignore Neighbor Discovery messages (Neighbor
Solicitation, Neighbor Advertisement, Router Solcicitation, and
Router Advertisement messages) that employ IPv6 Extension Headers.
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3. Security Considerations
IPv6 Extension Headers can be leveraged to circumvent network
monitoring and mechanisms such as RA-Guard
[I-D.gont-v6ops-ra-guard-evasion]. By updating the relevant
specifications such that IPv6 Extension Headers are not allowed in
Neighbor Discovery messages, protection of local network against
Neighbor Discovery attacks, and monitoring of Neighbor Discovery
traffic is greatly simplified.
[I-D.gont-v6ops-ra-guard-evasion] discusses an improvement to the RA-
Guard mechanism that can mitigate Neighbor Discovery attacks that
employ IPv6 Extension Headers. However, it should be noted that
unless [RFC4861] is updated (as proposed in this document) such that
use of IPv6 extension headers is not allowed with Neighbor Discovery
messages, monitoring of Neighbor Discovery traffic and mitigation of
Neighbor Discovery vulnerabilities will probably imply increased
complexity and/or reduced performance in the corresponding devices
(RA-Guard box, Network Intrusion Detection Systems, etc.).
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4. Acknowledgements
The author would like to thank Arturo Servin for providing valuable
comments on earlier versions of this document.
This document resulted from the project "Security Assessment of the
Internet Protocol version 6 (IPv6)" [CPNI-IPv6], carried out by
Fernando Gont on behalf of the UK Centre for the Protection of
National Infrastructure (CPNI). The author would like to thank the
UK CPNI, for their continued support.
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5. References
5.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.
5.2. Informative References
[RFC6104] Chown, T. and S. Venaas, "Rogue IPv6 Router Advertisement
Problem Statement", RFC 6104, February 2011.
[RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J.
Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105,
February 2011.
[NDPMon] "NDPMon - IPv6 Neighbor Discovery Protocol Monitor",
<http://ndpmon.sourceforge.net/>.
[I-D.gont-v6ops-ra-guard-evasion]
Gont, F. and U. CPNI, "IPv6 Router Advertisement Guard
(RA-Guard) Evasion", draft-gont-v6ops-ra-guard-evasion-00
(work in progress), May 2011.
[CPNI-IPv6]
Gont, F., "Security Assessment of the Internet Protocol
version 6 (IPv6)", UK Centre for the Protection of
National Infrastructure, (to be published).
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Appendix A. Changes from previous versions of the draft (to be removed
by the RFC Editor before publication of this document as a
RFC
A.1. Changes from draft-gont-6man-nd-extension-headers-00
o The Security Considerations section now notes that unless IPv6
extension headers are not allowed with Neighbor Discovery
messages, monitoring ND traffic and/or mitigating ND
vulnerabilities might result in increased complexity and/or
reduced performance.
o Minor editorial changes
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Author's Address
Fernando Gont
Centre for the Protection of National Infrastructure
Email: fernando@gont.com.ar
URI: http://www.gont.com.ar
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