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)
145 lines
5.8 KiB
Text
145 lines
5.8 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA1
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=============================================================================
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FreeBSD-SA-08:10.nd6 Security Advisory
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The FreeBSD Project
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Topic: IPv6 Neighbor Discovery Protocol routing vulnerability
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Category: core
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Module: sys_netinet6
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Announced: 2008-10-01
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Credits: David Miles
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Affects: All supported versions of FreeBSD.
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Corrected: 2008-10-01 00:32:59 UTC (RELENG_7, 7.1-PRERELEASE)
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2008-10-01 00:32:59 UTC (RELENG_7_0, 7.0-RELEASE-p5)
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2008-10-01 00:32:59 UTC (RELENG_6, 6.4-PRERELEASE)
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2008-10-01 00:32:59 UTC (RELENG_6_3, 6.3-RELEASE-p5)
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CVE Name: CVE-2008-2476
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For general information regarding FreeBSD Security Advisories,
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including descriptions of the fields above, security branches, and the
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following sections, please visit <URL:http://security.FreeBSD.org/>.
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I. Background
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IPv6 nodes use the Neighbor Discovery protocol to determine the link-layer
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address of other nodes, find routers, and maintain reachability information.
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The Neighbor Discovery protocol uses Neighbor Solicitation (ICMPv6 type 135)
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to query target nodes for their link-layer addresses.
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II. Problem Description
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IPv6 routers may allow "on-link" IPv6 nodes to create and update the
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router's neighbor cache and forwarding information. A malicious IPv6 node
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sharing a common router but on a different physical segment from another
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node may be able to spoof Neighbor Discovery messages, allowing it to update
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router information for the victim node.
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III. Impact
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An attacker on a different physical network connected to the same IPv6
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router as another node could redirect IPv6 traffic intended for that node.
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This could lead to denial of service or improper access to private network
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traffic.
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IV. Workaround
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Firewall packet filters can be used to filter incoming Neighbor
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Solicitation messages but may interfere with normal IPv6 operation if not
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configured carefully.
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Reverse path forwarding checks could be used to make gateways, such as
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routers or firewalls, drop Neighbor Solicitation messages from
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nodes with unexpected source addresses on a particular interface.
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IPv6 router administrators are encouraged to read RFC 3756 for further
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discussion of Neighbor Discovery security implications.
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V. Solution
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NOTE WELL: The solution described below causes IPv6 Neighbor Discovery
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Neighbor Solicitation messages from non-neighbors to be ignored.
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This can be re-enabled if required by setting the newly added
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net.inet6.icmp6.nd6_onlink_ns_rfc4861 sysctl to a non-zero value.
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Perform one of the following:
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1) Upgrade your vulnerable system to 6-STABLE, or 7-STABLE, or to the
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RELENG_7_0, or RELENG_6_3 security branch dated after the correction
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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 6.3 and
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7.0 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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[FreeBSD 6.3]
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# fetch http://security.FreeBSD.org/patches/SA-08:10/nd6-6.patch
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# fetch http://security.FreeBSD.org/patches/SA-08:10/nd6-6.patch.asc
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[FreeBSD 7.0]
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# fetch http://security.FreeBSD.org/patches/SA-08:10/nd6-7.patch
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# fetch http://security.FreeBSD.org/patches/SA-08:10/nd6-7.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_6
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src/sys/netinet6/in6.h 1.36.2.10
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src/sys/netinet6/in6_proto.c 1.32.2.10
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src/sys/netinet6/nd6.h 1.19.2.4
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src/sys/netinet6/nd6_nbr.c 1.29.2.11
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RELENG_6_3
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src/UPDATING 1.416.2.37.2.10
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src/sys/conf/newvers.sh 1.69.2.15.2.9
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src/sys/netinet6/in6.h 1.36.2.8.2.1
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src/sys/netinet6/in6_proto.c 1.32.2.8.2.1
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src/sys/netinet6/nd6.h 1.19.2.2.6.1
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src/sys/netinet6/nd6_nbr.c 1.29.2.9.2.1
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RELENG_7
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src/sys/netinet6/in6.h 1.51.2.2
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src/sys/netinet6/in6_proto.c 1.46.2.3
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src/sys/netinet6/nd6.h 1.21.2.2
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src/sys/netinet6/nd6_nbr.c 1.47.2.3
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RELENG_7_0
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src/UPDATING 1.507.2.3.2.9
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src/sys/conf/newvers.sh 1.72.2.5.2.9
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src/sys/netinet6/in6.h 1.51.4.1
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src/sys/netinet6/in6_proto.c 1.46.4.1
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src/sys/netinet6/nd6.h 1.21.4.1
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src/sys/netinet6/nd6_nbr.c 1.47.4.1
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- -------------------------------------------------------------------------
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VII. References
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http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-2476
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http://www.kb.cert.org/vuls/id/472363
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The latest revision of this advisory is available at
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http://security.FreeBSD.org/advisories/FreeBSD-SA-08:10.nd6.asc
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