3571e53040
patches for easier mirroring, to eliminate a special copy, to make www.freebsd.org/security a full copy of security.freebsd.org and be eventually be the same. For now files are just sitting there. The symlinks are missing. Discussed on: www (repository location) Discussed with: simon (so)
136 lines
5.3 KiB
Text
136 lines
5.3 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA1
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=============================================================================
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FreeBSD-SA-07:03.ipv6 Security Advisory
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The FreeBSD Project
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Topic: IPv6 Routing Header 0 is dangerous
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Category: core
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Module: ipv6
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Announced: 2007-04-26
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Credits: Philippe Biondi, Arnaud Ebalard, Jun-ichiro itojun Hagino
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Affects: All FreeBSD releases.
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Corrected: 2007-04-24 11:42:42 UTC (RELENG_6, 6.2-STABLE)
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2007-04-26 23:42:23 UTC (RELENG_6_2, 6.2-RELEASE-p4)
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2007-04-26 23:41:59 UTC (RELENG_6_1, 6.1-RELEASE-p16)
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2007-04-24 11:44:23 UTC (RELENG_5, 5.5-STABLE)
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2007-04-26 23:41:27 UTC (RELENG_5_5, 5.5-RELEASE-p12)
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CVE Name: CVE-2007-2242
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I. Background
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IPv6 provides a routing header option which allows a packet sender to
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indicate how the packet should be routed, overriding the routing knowledge
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present in a network. This functionality is roughly equivalent to the
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"source routing" option in IPv4. All nodes in an IPv6 network -- both
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routers and hosts -- are required by RFC 2460 to process such headers.
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II. Problem Description
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There is no mechanism for preventing IPv6 routing headers from being used
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to route packets over the same link(s) many times.
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III. Impact
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An attacker can "amplify" a denial of service attack against a link between
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two vulnerable hosts; that is, by sending a small volume of traffic the
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attacker can consume a much larger amount of bandwidth between the two
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vulnerable hosts.
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An attacker can use vulnerable hosts to "concentrate" a denial of service
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attack against a victim host or network; that is, a set of packets sent
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over a period of 30 seconds or more could be constructed such that they
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all arrive at the victim within a period of 1 second or less.
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Other attacks may also be possible.
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IV. Workaround
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No workaround is available.
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V. Solution
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NOTE WELL: The solution described below causes IPv6 type 0 routing headers
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to be ignored. Support for IPv6 type 0 routing headers can be re-enabled
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if required by setting the newly added net.inet6.ip6.rthdr0_allowed sysctl
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to a non-zero value.
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Perform one of the following:
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1) Upgrade your vulnerable system to 5-STABLE, or 6-STABLE, or to the
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RELENG_6_2, RELENG_6_1, or RELENG_5_5 security branch dated after the
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correction date.
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2) To patch your present system:
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The following patches have been verified to apply to FreeBSD 5.5, 6.1,
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and 6.2 systems.
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a) Download the relevant patch from the location below, and verify the
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detached PGP signature using your PGP utility.
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# fetch http://security.FreeBSD.org/patches/SA-07:03/ipv6.patch
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# fetch http://security.FreeBSD.org/patches/SA-07:03/ipv6.patch.asc
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b) Apply the patch.
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# cd /usr/src
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# patch < /path/to/patch
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c) Recompile your kernel as described in
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<URL:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
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system.
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VI. Correction details
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The following list contains the revision numbers of each file that was
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corrected in FreeBSD.
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Branch Revision
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Path
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- -------------------------------------------------------------------------
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RELENG_5
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src/sys/netinet6/in6.h 1.35.2.5
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src/sys/netinet6/in6_proto.c 1.29.2.5
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src/sys/netinet6/route6.c 1.10.4.2
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RELENG_5_5
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src/UPDATING 1.342.2.35.2.12
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src/sys/conf/newvers.sh 1.62.2.21.2.14
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src/sys/netinet6/in6.h 1.35.2.3.2.1
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src/sys/netinet6/in6_proto.c 1.29.2.4.2.1
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src/sys/netinet6/route6.c 1.10.4.1.4.1
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RELENG_6
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src/sys/netinet6/in6.h 1.36.2.8
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src/sys/netinet6/in6_proto.c 1.32.2.6
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src/sys/netinet6/route6.c 1.11.2.2
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RELENG_6_2
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src/UPDATING 1.416.2.29.2.7
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src/sys/conf/newvers.sh 1.69.2.13.2.7
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src/sys/netinet6/in6.h 1.36.2.7.2.1
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src/sys/netinet6/in6_proto.c 1.32.2.5.2.1
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src/sys/netinet6/route6.c 1.11.2.1.4.1
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RELENG_6_1
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src/UPDATING 1.416.2.22.2.18
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src/sys/conf/newvers.sh 1.69.2.11.2.18
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src/sys/netinet6/in6.h 1.36.2.6.2.1
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src/sys/netinet6/in6_proto.c 1.32.2.4.2.1
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src/sys/netinet6/route6.c 1.11.2.1.2.1
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- -------------------------------------------------------------------------
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VII. References
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http://www.secdev.org/conf/IPv6_RH_security-csw07.pdf
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http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2242
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The latest revision of this advisory is available at
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http://security.FreeBSD.org/advisories/FreeBSD-SA-07:03.ipv6.asc
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-----END PGP SIGNATURE-----
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