NetBSD IPv6 Neighbor Discovery Protocol Spoofing Bug Lets Remote Users Modify Routing Data in Certain Cases
SecurityTracker Alert ID: 1021109|
SecurityTracker URL: http://securitytracker.com/id/1021109
(Links to External Site)
Date: Oct 27 2008
Disclosure of system information, Disclosure of user information, Modification of system information|
Fix Available: Yes Vendor Confirmed: Yes |
Version(s): 3.0, 3.1, 4.0|
A vulnerability was reported in the NetBSD 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.
A remote user can modify routing data for a target router in certain cases to deny service or redirect and access network traffic.|
The vendor has issued a source code fix.|
The vendor's advisory is available at:
Vendor URL: ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2008-013.txt.asc (Links to External Site)
Source Message Contents
Subject: NetBSD Security Advisory 2008-013: IPv6 Neighbor Discovery Protocol|
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NetBSD Security Advisory 2008-013
Topic: IPv6 Neighbor Discovery Protocol
Version: NetBSD-current: affected
NetBSD 4.0.*: not affected
NetBSD 4.0: affected
NetBSD 3.1.*: affected
NetBSD 3.1: affected
NetBSD 3.0.*: affected
NetBSD 3.0: affected
Severity: Denial of service
Fixed: NetBSD-current: July 31, 2008
NetBSD-4-0 branch: October 03, 2008
(4.0.1 includes the fix)
NetBSD-4 branch: October 03, 2008
(4.1 will include the fix)
NetBSD-3-1 branch: October 03, 2008
(3.1.2 will include the fix)
NetBSD-3-0 branch: October 03, 2008
(3.0.4 will include the fix)
NetBSD-3 branch: October 03, 2008
(3.2 will include the fix)
An attacker may be able to forge IPv6 routing entries to intercept network
traffic or cause a denial of service attack.
This vulnerability has been assigned CVE-2008-2476 and CERT
Vulnerability Note VU#472363.
An attacker on a local network (i.e. the messages will not be forwarded by
routers) can send a ICMPv6 neighbor solicitation message to a router which
will result in a modification of the victims routing information. It may be
then possible for the attacker intercept network traffic or cause a denial
Solutions and Workarounds
Only kernels compiled with the following option are vulnerable to this issue:
As a temporary workaround recompile the kernel with the above option
commented out. The default NetBSD GENERIC kernels have this
In addition to this the following work arounds may also be used:
* Use application level encryption (e.g. SSH, HTTPS) to protect sensitive
* Use network firewalls to block any malicious ICMPv6 neighbor solicitation
For all NetBSD versions, you need to obtain fixed kernel sources,
rebuild and install the new kernel, and reboot the system.
The fixed source may be obtained from the NetBSD CVS repository.
The following instructions briefly summarise how to upgrade your
kernel. In these instructions, replace:
ARCH with your architecture (from uname -m), and
KERNCONF with the name of your kernel configuration file.
To update from CVS, re-build, and re-install the kernel:
# cd src
# cvs update sys/netinet6/nd6_nbr.c sys/netinet6/in6.c \
# ./build.sh kernel=KERNCONF
# mv /netbsd /netbsd.old
# cp sys/arch/ARCH/compile/obj/KERNCONF/netbsd /netbsd
# shutdown -r now
For more information on how to do this, see:
Matt Thomas for the fix.
David Miles is credited with discovering this issue.
2008-10-27 Initial release
Advisories may be updated as new information becomes available.
The most recent version of this advisory (PGP signed) can be found at
Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.org/ and http://www.NetBSD.org/Security/.
Copyright 2008, The NetBSD Foundation, Inc. All Rights Reserved.
Redistribution permitted only in full, unmodified form.
$NetBSD: NetBSD-SA2008-013.txt,v 1.3 2008/10/27 19:47:21 adrianp Exp $
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