FreeBSD IPv6 Neighbor Discovery Protocol Spoofing Bug Lets Remote Users Modify Routing Data in Certain Cases
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SecurityTracker Alert ID: 1020968 |
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SecurityTracker URL: http://securitytracker.com/id/1020968
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CVE Reference:
CVE-2008-2476
(Links to External Site)
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Date: Oct 2 2008
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Impact:
Disclosure of system information, Disclosure of user information, Modification of system information
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Fix Available: Yes Vendor Confirmed: Yes
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Version(s): 6.3, 6.4, 7.0, 7.1
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Description:
A vulnerability was reported in the FreeBSD IPv6 Neighbor Discovery Protocol. A remote user can modify routing data for a target router in certain cases.
A remote user on a physical network of an IPv6 router can spoof Neighbor Discovery messages to update routing information for a target router on a different physical network adjacent to the IPv6 router. The remote user can exploit this to deny service or access network traffic from the target router.
David Miles reported this vulnerability.
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Impact:
A remote user can modify routing data for a target router in certain cases to deny service or redirect and access network traffic.
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Solution:
The vendor has issued a fix and provided the following solution instructions [quoted].
Perform one of the following:
1) Upgrade your vulnerable system to 6-STABLE, or 7-STABLE, or to the
RELENG_7_0, or RELENG_6_3 security branch dated after the correction
date.
2) To patch your present system:
The following patches have been verified to apply to FreeBSD 6.3 and
7.0 systems.
a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.
[FreeBSD 6.3]
# fetch http://security.FreeBSD.org/patches/SA-08:10/nd6-6.patch
# fetch http://security.FreeBSD.org/patches/SA-08:10/nd6-6.patch.asc
[FreeBSD 7.0]
# fetch http://security.FreeBSD.org/patches/SA-08:10/nd6-7.patch
# fetch http://security.FreeBSD.org/patches/SA-08:10/nd6-7.patch.asc
b) Apply the patch.
# cd /usr/src
# patch < /path/to/patch
c) Recompile your kernel as described in
<URL:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
system.
The vendor's advisory is available at:
http://security.FreeBSD.org/advisories/FreeBSD-SA-08:10.nd6.asc
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Vendor URL: security.FreeBSD.org/advisories/FreeBSD-SA-08:10.nd6.asc (Links to External Site)
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Cause:
Authentication error
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Underlying OS:
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Message History:
This archive entry has one or more follow-up message(s) listed below.
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Source Message Contents
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Date: Thu, 2 Oct 2008 00:39:20 GMT
Subject: FreeBSD Security Advisory FreeBSD-SA-08:10.nd6
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-----BEGIN PGP SIGNED MESSAGE-----
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=============================================================================
FreeBSD-SA-08:10.nd6 Security Advisory
The FreeBSD Project
Topic: IPv6 Neighbor Discovery Protocol routing vulnerability
Category: core
Module: sys_netinet6
Announced: 2008-10-01
Credits: David Miles
Affects: All supported versions of FreeBSD.
Corrected: 2008-10-01 00:32:59 UTC (RELENG_7, 7.1-PRERELEASE)
2008-10-01 00:32:59 UTC (RELENG_7_0, 7.0-RELEASE-p5)
2008-10-01 00:32:59 UTC (RELENG_6, 6.4-PRERELEASE)
2008-10-01 00:32:59 UTC (RELENG_6_3, 6.3-RELEASE-p5)
CVE Name: CVE-2008-2476
For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:http://security.FreeBSD.org/>.
I. Background
IPv6 nodes use the Neighbor Discovery protocol to determine the link-layer
address of other nodes, find routers, and maintain reachability information.
The Neighbor Discovery protocol uses Neighbor Solicitation (ICMPv6 type 135)
to query target nodes for their link-layer addresses.
II. Problem Description
IPv6 routers may allow "on-link" IPv6 nodes to create and update the
router's neighbor cache and forwarding information. A malicious IPv6 node
sharing a common router but on a different physical segment from another
node may be able to spoof Neighbor Discovery messages, allowing it to update
router information for the victim node.
III. Impact
An attacker on a different physical network connected to the same IPv6
router as another node could redirect IPv6 traffic intended for that node.
This could lead to denial of service or improper access to private network
traffic.
IV. Workaround
Firewall packet filters can be used to filter incoming Neighbor
Solicitation messages but may interfere with normal IPv6 operation if not
configured carefully.
Reverse path forwarding checks could be used to make gateways, such as
routers or firewalls, drop Neighbor Solicitation messages from
nodes with unexpected source addresses on a particular interface.
IPv6 router administrators are encouraged to read RFC 3756 for further
discussion of Neighbor Discovery security implications.
V. Solution
NOTE WELL: The solution described below causes IPv6 Neighbor Discovery
Neighbor Solicitation messages from non-neighbors to be ignored.
This can be re-enabled if required by setting the newly added
net.inet6.icmp6.nd6_onlink_ns_rfc4861 sysctl to a non-zero value.
Perform one of the following:
1) Upgrade your vulnerable system to 6-STABLE, or 7-STABLE, or to the
RELENG_7_0, or RELENG_6_3 security branch dated after the correction
date.
2) To patch your present system:
The following patches have been verified to apply to FreeBSD 6.3 and
7.0 systems.
a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.
[FreeBSD 6.3]
# fetch http://security.FreeBSD.org/patches/SA-08:10/nd6-6.patch
# fetch http://security.FreeBSD.org/patches/SA-08:10/nd6-6.patch.asc
[FreeBSD 7.0]
# fetch http://security.FreeBSD.org/patches/SA-08:10/nd6-7.patch
# fetch http://security.FreeBSD.org/patches/SA-08:10/nd6-7.patch.asc
b) Apply the patch.
# cd /usr/src
# patch < /path/to/patch
c) Recompile your kernel as described in
<URL:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
system.
VI. Correction details
The following list contains the revision numbers of each file that was
corrected in FreeBSD.
Branch Revision
Path
- -------------------------------------------------------------------------
RELENG_6
src/sys/netinet6/in6.h 1.36.2.10
src/sys/netinet6/in6_proto.c 1.32.2.10
src/sys/netinet6/nd6.h 1.19.2.4
src/sys/netinet6/nd6_nbr.c 1.29.2.11
RELENG_6_3
src/UPDATING 1.416.2.37.2.10
src/sys/conf/newvers.sh 1.69.2.15.2.9
src/sys/netinet6/in6.h 1.36.2.8.2.1
src/sys/netinet6/in6_proto.c 1.32.2.8.2.1
src/sys/netinet6/nd6.h 1.19.2.2.6.1
src/sys/netinet6/nd6_nbr.c 1.29.2.9.2.1
RELENG_7
src/sys/netinet6/in6.h 1.51.2.2
src/sys/netinet6/in6_proto.c 1.46.2.3
src/sys/netinet6/nd6.h 1.21.2.2
src/sys/netinet6/nd6_nbr.c 1.47.2.3
RELENG_7_0
src/UPDATING 1.507.2.3.2.9
src/sys/conf/newvers.sh 1.72.2.5.2.9
src/sys/netinet6/in6.h 1.51.4.1
src/sys/netinet6/in6_proto.c 1.46.4.1
src/sys/netinet6/nd6.h 1.21.4.1
src/sys/netinet6/nd6_nbr.c 1.47.4.1
- -------------------------------------------------------------------------
VII. References
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-2476
http://www.kb.cert.org/vuls/id/472363
The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-08:10.nd6.asc
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