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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2007.0700 -- [NetBSD] IPv6 Type 0 Routing Header 14 September 2007 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Publisher: NetBSD Operating System: NetBSD Impact: Denial of Service Access: Remote/Unauthenticated CVE Names: CVE-2007-2242 Ref: ESB-2007.0261 Original Bulletin: ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2007-005.txt.asc - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 NetBSD Security Advisory 2007-005 ================================= Topic: IPv6 Type 0 Routing Header Version: NetBSD-current: source prior to April 22, 2007 NetBSD 4.0_BETA2 affected NetBSD 3.1: affected NetBSD 3.0.*: affected NetBSD 3.0: affected NetBSD 2.1: affected NetBSD 2.0.*: affected NetBSD 2.0: affected Severity: Remote Denial of Service Fixed: NetBSD-current: April 22, 2007 NetBSD-4 branch: April 28, 2007 (4.0 will include the fix) NetBSD-3-1 branch April 26, 2007 (3.1.1 will include the fix) NetBSD-3-0 branch: April 26, 2007 (3.0.3 will include the fix) NetBSD-3 branch: April 26, 2007 NetBSD-2-1 branch: June 04, 2007 NetBSD-2-0 branch: June 04, 2007 NetBSD-2 branch: June 04, 2007 Abstract ======== A crafted IPv6 Type 0 Routing Header packet(s) can be used to launch a denial of service attack on an IPv6 host. This vulnerability has been assigned CVE reference CVE-2007-2242. Technical Details ================= A remote attacker can transmit crafted IPv6 packets using a Type 0 Routing Header. The result is a type of denial of service attack known as a traffic amplification attack where the bandwidth between the sending and receiving hosts increases during the attack. Solutions and Workarounds ========================= To rectify these problems a kernel built from sources containing the fixes must be installed and the system rebooted. The fixes introduce a new sysctl(8) that can be used to control the processing of IPv6 type 0 packets. The new sysctl is named net.inet6.ip6.rht0 and has three possible values: -1 Processing is disabled (default). 0 Processing is enabled only for routers and not for hosts. 1 Processing is enabled for both routers and hosts. NOTE: This sysctl was later removed from NetBSD-current on May 17 2007 and the default was hard set to drop IPv6 type 0 packets. This sysctl may disappear from future NetBSD releases. The following instructions describe how to upgrade your kernel by updating your source tree and rebuilding and installing a new version of the kernel. For more information on how to do this, see: http://www.NetBSD.org/guide/en/chap-kernel.html * NetBSD-current: Systems running NetBSD-current dated from before 2007-04-22 should be upgraded to NetBSD-current dated 2007-04-23 or later. The following files need to be updated from the netbsd-current CVS branch (aka HEAD): sys/netinet6/ip6_input.c sys/netinet6/ip6_var.h sys/netinet6/route6.c share/man/man7/sysctl.7 To update from CVS, re-build, and re-install a kernel containing the fix: # cd src # cvs update sys/netinet6/ip6_input.c # cvs update sys/netinet6/ip6_var.h # cvs update sys/netinet6/route6.c # cvs update share/man/man7/sysctl.7 # build.sh tools kernel=KERNCONFFILE * NetBSD 3.*: Systems running NetBSD 3.* sources dated from before 2007-04-26 should be upgraded from NetBSD 3.* sources dated 2007-04-27 or later. The following files need to be updated from the netbsd-3, netbsd-3-0 or netbsd-3-1 branches: sys/netinet6/ip6_input.c sys/netinet6/ip6_var.h sys/netinet6/route6.c sbin/sysctl/sysctl.8 To update from CVS, re-build, and re-install a kernel containing the fix: # cd src # cvs update -r <branch_name> sys/netinet6/ip6_input.c # cvs update -r <branch_name> sys/netinet6/ip6_var.h # cvs update -r <branch_name> sys/netinet6/route6.c # cvs update -r <branch_name> sbin/sysctl/sysctl.8 # build.sh tools kernel=KERNCONFFILE * NetBSD 2.*: Systems running NetBSD 2.* sources dated from before 2007-06-04 should be upgraded from NetBSD 2.* sources dated 2007-06-05 or later. The following files need to be updated from the netbsd-2, netbsd-2-0 or netbsd-2-1 CVS branches: sys/netinet6/ip6_input.c sys/netinet6/ip6_var.h sys/netinet6/route6.c sbin/sysctl/sysctl.8 To update from CVS, re-build, and re-install a kernel containing the fix: # cd src # cvs update -r <branch_name> sys/netinet6/ip6_input.c # cvs update -r <branch_name> sys/netinet6/ip6_var.h # cvs update -r <branch_name> sys/netinet6/route6.c # cvs update -r <branch_name> sbin/sysctl/sysctl.8 # build.sh tools kernel=KERNCONFFILE Thanks To ========= Philippe Biondi and Arnaud Ebalard for discovering and reporting this problem. Revision History ================ 2007-09-13 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-SA2007-005.txt.asc Information about NetBSD and NetBSD security can be found at http://www.NetBSD.org/ and http://www.NetBSD.org/Security/. Copyright 2007, The NetBSD Foundation, Inc. All Rights Reserved. Redistribution permitted only in full, unmodified form. $NetBSD: rt14129_RH0.txt,v 1.3 2007/08/18 20:37:42 mjf Exp $ - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (NetBSD) iQCVAwUBRuhdNz5Ru2/4N2IFAQLEkwP/Q8npU5jzm/s95MYHECcGTdW5xPOZu5Pv UHd8W8/k8e7BygW8hhfrXZQjFmglDsdvkwQL5stPQeWNmYdJAe280UAwn6v+FoTw LwraKzI82iV1tYhBGlq/TbrkGI4JOmEqpUqqSGtGDnrYT7ZgU0/87VGyHCftvOjE e0KiJD5McZU= =1z0U - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. 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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 iQCVAwUBRun7rSh9+71yA2DNAQL1+QP+NTKyX78vxZfAXHEvXnVKxBLtAsDXCfK1 FfzUBMxpBRKF0YcmBa9zgYetWD9Z4HAGFXG9zf1XujvFPOjEmRAoD7ifZHC2SJTG MaEQU1St9yg0K9THgmwlzgOEK4Ab5OmkhHA1QEJt467skEZRcWryCDWbgJYJHVAn EtI6BSxX96o= =YZtO -----END PGP SIGNATURE-----