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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2006.0394 -- [NetBSD] IPv6 socket options can crash the system 9 June 2006 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: IPv6 Sockets Publisher: NetBSD Operating System: NetBSD-current NetBSD 3.0 NetBSD 2.1 NetBSD 2.0.* NetBSD 2.0 Impact: Denial of Service Access: Existing Account Original Bulletin: ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2006-016.txt.asc - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 NetBSD Security Advisory 2006-016 ================================= Topic: IPv6 socket options can crash the system Version: NetBSD-current: source prior to May 23, 2006 NetBSD 3.0: affected NetBSD 2.1: affected NetBSD 2.0.*: affected NetBSD 2.0: affected Severity: Any local user can crash the system Fixed: NetBSD-current: May 23, 2006 NetBSD-3-0 branch: May 24, 2006 (3.0.1 will include the fix) NetBSD-3 branch: May 24, 2006 NetBSD-2-1 branch: May 24, 2006 (2.1.1 will include the fix) NetBSD-2-0 branch: May 24, 2006 (2.0.4 will include the fix) NetBSD-2 branch: May 24, 2006 Abstract ======== Insufficient validation when parsing IPv6 socket options can lead to a system crash. This can be triggered by a local non-privileged user. Technical Details ================= IPv6 sockets can be used with IPv4-mapped addresses, and thus IPv4 packets may be sent and delivered through an IPv6 socket. When sending an IPv6 packet, the NetBSD kernel needs to call the ip6_savecontrol() function in order to process the SO_TIMESTAMP socket option. This function should process options for IPv6 packets only, but wasn't checking for IPv4-mapped sockets. If such a socket had this option set, it would traverse the mbuf chain by later calling ip6_pullexthdr(), causing a panic. Either net.inet6.ip6.v6only sysctl MIB (global) or IPV6_V6ONLY socket option (per-socket) need to be 0 (zero) for this code path to occur. Solutions and Workarounds ========================= By default on NetBSD net.inet6.ip6.v6only is set to 1 (disabled). However, any user can set IPV6_V6ONLY on their own sockets. The only workaround available is to rebuild a kernel with "options BIND_V6ONLY". 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 -d -P sys/netinet6/ip6_input.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: http://www.NetBSD.org/guide/en/chap-kernel.html Thanks To ========= Christian Biere for finding the problem. JINMEI Tatuya from the KAME project for the fix. Rui Paulo for implementing the fixes. Revision History ================ 2006-06-08 Initial release More Information ================ Advisories may be updated as new information becomes available. The most recent version of this advisory (PGP signed) can be found at ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2006-016.txt.asc Information about NetBSD and NetBSD security can be found at http://www.NetBSD.org/ and http://www.NetBSD.org/Security/. Copyright 2006, The NetBSD Foundation, Inc. All Rights Reserved. Redistribution permitted only in full, unmodified form. $NetBSD: NetBSD-SA2006-016.txt,v 1.2 2006/06/08 16:21:43 adrianp Exp $ - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (NetBSD) iQCVAwUBRIhPHz5Ru2/4N2IFAQKlHAP/Qk4xp1No/NASozQZgFpTIobWpJzgsu7/ XJuJt4nsfeSsJuISTq5wOy6nYZcGrSji8JsAkJttSzvAQsnHFxhgd2lBIAUlmmOS SvnMLOmKpOZjn4pqdeJBlRPOJSnMNPYLZ2lD8smrRcMtvwjAA2E1y27iwM8wKEkh uR16rsZVkZ8= =vsfj - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. 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If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 If you believe that your computer system has been compromised or attacked in any way, we encourage you to let us know by completing the secure National IT Incident Reporting Form at: http://www.auscert.org.au/render.html?it=3192 =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQCVAwUBRIiw2yh9+71yA2DNAQJSkQP/bdZNsDart2d8HSxGLm5Dyb71tTc90Wnr FG3O2LQ1uJqzsSuwAaKHA1f4u1HpbyAf2ACIXiqiClWTHRrswtd682BWdNPMjJjd kxjGaGOGcVtkAvAQooxAavK5YqeA6N3DhHWNeMSIPBOo/kBnHaHRVMLzHFN1YYTl Mvzf6IpQiu0= =reor -----END PGP SIGNATURE-----