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             AUSCERT External Security Bulletin Redistribution

                        ESB-2007.0261 -- [OpenBSD]
                   IPv6 Type 0 Route Header Design Flaw
                               27 April 2007

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:              IPv6
Publisher:            OpenBSD
Operating System:     Various IPv6 router platforms
                      OpenBSD
Impact:               Denial of Service
Access:               Remote/Unauthenticated
CVE Names:            CVE-2007-2242

Original Bulletin:    http://openbsd.org/errata40.html#012_route6

Comment: Detailed information on the security problems caused by type 0
         routing headers in IPv6 and mitigation on various router platforms
         is provided in the following presentation:
         
           http://www.secdev.org/conf/IPv6_RH_security-csw07.pdf
         
         Attacks facilitated by this protocol feature include
         - Denial of service attack amplification
         - Denial of service attack concentration in time
         - Potential evasion of some firewalls and IDS
         - Defeating anycast routing

Revision History:  
  April 27 2007: Added CVE and link to further information
  April 24 2007: Initial Release

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IPv6 type 0 route headers can be used to mount a DoS attack against
hosts and networks.  This is a design flaw in IPv6 and not a bug in
OpenBSD.

This problem has been fixed in the OpenBSD CVS repository in the
- -current and -stable branches.  The -current snapshots of OpenBSD
contain these fixes as well.

It is recommended that users of OpenBSD update their kernel asap
using cvs or manually apply the source code patches listed below.

A source code patch for OpenBSD 4.0-stable can be downloaded from
ftp://ftp.openbsd.org/pub/OpenBSD/patches/4.0/common/012_route6.patch.

A source code patch for OpenBSD 3.9-stable can be downloaded from
ftp://ftp.openbsd.org/pub/OpenBSD/patches/3.9/common/022_route6.patch.

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===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
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