--- 1/draft-ietf-ipv6-deprecate-rh0-00.txt 2007-06-28 22:12:08.000000000 +0200 +++ 2/draft-ietf-ipv6-deprecate-rh0-01.txt 2007-06-28 22:12:08.000000000 +0200 @@ -1,21 +1,21 @@ Network Working Group J. Abley Internet-Draft Afilias -Updates: 2460 (if approved) P. Savola -Intended status: Standards Track CSC/FUNET -Expires: November 17, 2007 G. Neville-Neil - Neville-Neil Consulting - May 16, 2007 +Updates: 2460, 4294 P. Savola +(if approved) CSC/FUNET +Intended status: Standards Track G. Neville-Neil +Expires: December 28, 2007 Neville-Neil Consulting + June 26, 2007 Deprecation of Type 0 Routing Headers in IPv6 - draft-ietf-ipv6-deprecate-rh0-00 + draft-ietf-ipv6-deprecate-rh0-01 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that @@ -26,171 +26,201 @@ 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. - This Internet-Draft will expire on November 17, 2007. + This Internet-Draft will expire on December 28, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract The functionality provided by IPv6's Type 0 Routing Header can be - exploited in order to perform remote network discovery, to bypass - firewalls and to achieve packet amplification for the purposes of - generating denial-of-service traffic. This document updates the IPv6 - specification to deprecate the use of IPv6 Type 0 Routing Headers, in - the light of these security concerns. - - This document updates RFC 2460. + exploited in order to achieve traffic amplification over a remote + path for the purposes of generating denial-of-service traffic. This + document updates the IPv6 specification to deprecate the use of IPv6 + Type 0 Routing Headers, in light of this security concern. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 3. Deprecation of RH0 . . . . . . . . . . . . . . . . . . . . . . 3 - 3.1. Origination . . . . . . . . . . . . . . . . . . . . . . . . 3 - 3.2. Processing . . . . . . . . . . . . . . . . . . . . . . . . 3 - 4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 4.1. Ingress Filtering . . . . . . . . . . . . . . . . . . . . . 3 - 4.2. Packet Filtering . . . . . . . . . . . . . . . . . . . . . 4 - 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 - 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 - 7. Acknowlegements . . . . . . . . . . . . . . . . . . . . . . . . 4 + 2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 3. Deprecation of RH0 . . . . . . . . . . . . . . . . . . . . . . 4 + 4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 4.1. Ingress Filtering . . . . . . . . . . . . . . . . . . . . . 4 + 4.2. Firewall Policy . . . . . . . . . . . . . . . . . . . . . . 4 + 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 + 7. Acknowlegements . . . . . . . . . . . . . . . . . . . . . . . . 5 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 8.1. Normative References . . . . . . . . . . . . . . . . . . . 5 - 8.2. Informative References . . . . . . . . . . . . . . . . . . 5 + 8.2. Informative References . . . . . . . . . . . . . . . . . . 6 Appendix A. Change History . . . . . . . . . . . . . . . . . . . . 6 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 - Intellectual Property and Copyright Statements . . . . . . . . . . 7 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 + Intellectual Property and Copyright Statements . . . . . . . . . . 9 1. Introduction [RFC2460] defines an IPv6 extension header called "Routing Header", identified by a Next Header value of 43 in the immediately preceding header. A particular Routing Header subtype denoted as "Type 0" is also defined. Type 0 Routing Headers are referred to as "RH0" in this document. - Use of RH0 has been shown to have unpleasant security implications, - some of which are summarised in Section 5. This document deprecates - the use of RH0. + A single RH0 may contain multiple intermediate node addresses, and + the same address may be included more than once in the same RH0. + This allows a packet to be constructed such that it will oscillate + between two RH0-processing hosts or routers many times. This allows + a stream of packets from an attacker to be amplified along the path + between two remote routers, which could be used to cause congestion + along arbitrary remote paths and hence act as a denial-of-service + mechanism. 88-fold amplification has been demonstrated using this + technique [CanSecWest07]. - This document updates [RFC2460]. + This attack is particularly serious in that it affects the entire + path between the two exploited nodes, not only the nodes themselves + or their local networks. Analogous functionality may be found in the + IPv4 source route option, but the opportunities for abuse are greater + with RH0 due to the ability to specify many more intermediate node + addresses in each packet. + + The severity of this threat is considered to be sufficient to warrant + deprecation of RH0 entirely. A side-effect is that this also + eliminates benign RH0 use-cases; however, such applications may be + facilitated by future Routing Header specifications. + + Potential problems with RH0 were identified in 2001 + [I-D.savola-ipv6-rh-ha-security]. In 2002 a proposal was made to + restrict Routing Header processing in hosts + [I-D.savola-ipv6-rh-hosts]. These efforts resulted in the + modification of the Mobile IPv6 specification to use the type 2 + Routing Header instead of RH0 [RFC3775]. Vishwas Manral identified + various risks associated with RH0 in 2006 including the amplification + attack; several of these vulnerabilities (together with other issues) + were later documented in [I-D.ietf-v6ops-security-overview]. + + A treatment of the operational security implications of RH0 was + presented by Philippe Biondi and Arnaud Ebalard at the CanSecWest + conference in Vancouver, 2007 [CanSecWest07]. This presentation + resulted in widespread publicity for the risks associated with RH0. + + This document updates [RFC2460] and [RFC4294]. 2. Definitions RH0 in this document denotes the IPv6 Extension Header type 43 ("Routing Header") variant 0 ("Type 0 Routing Header"), as defined in [RFC2460]. 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. Deprecation of RH0 -3.1. Origination + IPv6 nodes MUST NOT process RH0 in packets whose destination address + in the IPv6 header is an address assigned to them. Such packets MUST + be processed according to the behaviour specified in Section 4.4 of + [RFC2460] for a datagram which includes an unrecognised Routing Type + value, namely: - IPv6 nodes MUST NOT originate IPv6 packets containing RH0. + If Segments Left is zero, the node must ignore the Routing header + and proceed to process the next header in the packet, whose type + is identified by the Next Header field in the Routing header. -3.2. Processing + If Segments Left is non-zero, the node must discard the packet and + send an ICMP Parameter Problem, Code 0, message to the packet's + Source Address, pointing to the unrecognised Routing Type. - IPv6 nodes MUST NOT process RH0 in packets addressed to them. Such - packets MUST be processed according to the behaviour specified in - Section 4.4 of [RFC2460] for a datagram which includes an - unrecognised Routing Type value. + IPv6 implementations are no longer required to implement RH0 in any + way. 4. Operations 4.1. Ingress Filtering It is to be expected that it will take some time before all IPv6 nodes are updated to remove support for RH0. Some of the uses of RH0 described in [CanSecWest07] can be mitigated using ingress filtering, as recommended in [RFC2827] and [RFC3704]. -4.2. Packet Filtering + A site security policy intended to protect against attacks using RH0 + SHOULD include the implementation of ingress filtering at the site + border. - Firewall policy intended to protect against packets containing RH0 - should be constructed such that routing headers of other types (which - may well have legitimate and benign applications) are handled on - their own merits. For example, discarding all packets with any type - of routing header simply as a reaction to the problems with RH0 is - inappropriate, and may hamper future functionality designed using - non-type 0 routing headers. For example, Mobile IPv6 uses the type 2 - Routing Header [RFC3775]. +4.2. Firewall Policy - Where filtering capabilities do not facilitate matching specific - types of Routing Headers, filtering based on the presence of any - Routing Headers on IPv6 routers, regardless of type, is strongly - discouraged. + Blocking all IPv6 packets which carry Routing Headers (rather than + specifically blocking type 0, and permitting other types) has very + serious implications for the future development of IPv6. If even a + small percentage of deployed firewalls block other types of routing + headers by default, it will become impossible in practice to extend + IPv6 routing headers. For example, Mobile IPv6 [RFC3775] relies upon + a type-2 RH; wide-scale, indescriminate blocking of Routing Headers + will make Mobile IPv6 undeployable. + + Firewall policy intended to protect against packets containing RH0 + MUST NOT simply filter all traffic with a routing header; it must be + possible to disable forwarding of type 0 traffic without blocking + other types of routing headers. In addition, the default + configuration MUST permit forwarding of traffic using a RH other than + 0. 5. Security Considerations The purpose of this document is to deprecate a feature of IPv6 which - has been shown to have serious security implications. - - Specific examples of vulnerabilities which are facilitated by the - availability of RH0 can be found in [CanSecWest07]. + has been shown to have undesirable security implications. Specific + examples of vulnerabilities which are facilitated by the availability + of RH0 can be found in [CanSecWest07]. In particular, RH0 provides a + mechanism for traffic amplification, which might be used as a denial- + of-service attack. A description of this functionality can be found + in Section 1. 6. IANA Considerations The IANA registry "Internet Protocol Version 6 (IPv6) Parameters" should be updated to reflect that variant 0 of IPv6 header-type 43 ("Routing Header") is deprecated. 7. Acknowlegements - Potential problems with Routing Headers were identified in 2001 - [I-D.savola-ipv6-rh-ha-security]. In 2002 a proposal was made to - restrict Routing Header processing in hosts - [I-D.savola-ipv6-rh-hosts]. These efforts did not gain sufficient - momentum to change the IPv6 specification, but resulted in the - modification of the Mobile IPv6 specification to use the type 2 - Routing Header instead of RH0 [RFC3775]. Routing Header issues were - later documented in [I-D.ietf-v6ops-security-overview]. - - An eloquent and useful description of the operational security - implications of RH0 was presented by Philippe Biondi and Arnaud - Ebalard at the CanSecWest conference in Vancouver, 2007 - [CanSecWest07]. This presentation resulted in widespread publicity - for the risks associated with RH0. - - This document also benefits from the contributions of IPv6 and V6OPS - orking group participants, including Jari Arkko, Arbaud Ebalard, Tim - Enos, Brian Haberman, Jun-ichiro itojun HAGINO, Bob Hinden, JINMEI - Tatuya, David Malone, Jeroen Massar, Dave Thaler and Guillaume - Valadon. + This document benefits from the contributions of many IPV6 and V6OPS + working group participants, including Jari Arkko, Arnaud Ebalard, Tim + Enos, Brian Haberman, Jun-ichiro itojun HAGINO, Bob Hinden, Thomas + Narten, JINMEI Tatuya, David Malone, Jeroen Massar, Dave Thaler and + Guillaume Valadon. 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. + [RFC4294] Loughney, J., "IPv6 Node Requirements", RFC 4294, + April 2006. + 8.2. Informative References [CanSecWest07] BIONDI, P. and A. EBALARD, "IPv6 Routing Header Security", - April 2007. + CanSecWest Security Conference 2007, April 2007. http://www.secdev.org/conf/IPv6_RH_security-csw07.pdf [I-D.ietf-v6ops-security-overview] Davies, E., "IPv6 Transition/Co-existence Security Considerations", draft-ietf-v6ops-security-overview-06 (work in progress), October 2006. [I-D.savola-ipv6-rh-ha-security] Savola, P., "Security of IPv6 Routing Header and Home @@ -219,20 +249,39 @@ 00 Strawman, draft-jabley-ipv6-rh0-is-evil, circulated to provoke discussion. 01 Clarified Section 3; presented more options in Section 4; added Pekka and George as authors. This document version was not widely circulated. 00 Renamed, draft-ietf-ipv6-deprecate-rh0, a candidate working group document. + 01-candidate-00 Incorporated text summarising some of the unwelcome + uses of RH0; added some clariying text describing deprecation; + modified some ambiguous text in Section 4.2; added "Updates: + 4294". + + 01-candidate-01 Incorporated contributions from working group: + substantially reduced Section 5; clarified wording in Section 3. + + 01-candidate-02 Moved description of traffic amplification to + Section 1, and inserted a corresponding cross-reference in + Section 5. Strengthened the language in Section 4.2 along the + lines suggested by Thomas Narten. Small typos corrected. Added a + further sentence in Section 4.1 intended to act as further + encouragement for operators to implement [RFC3704]. + + 01 Minor wordsmithing; removed some subjective language; adopted + "intermediate node" nomenclature instead of "waypoint"; shifted + some history from Section 7 to Section 1. + Authors' Addresses Joe Abley Afilias Canada Corp. Suite 204, 4141 Yonge Street Toronto, ON M2P 2A8 Canada Phone: +1 416 673 4176 Email: jabley@ca.afilias.info