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             AUSCERT External Security Bulletin Redistribution

                               ESB-2012.1132
        A specific query can cause BIND nameservers using DNS64 to
                  exit with a REQUIRE assertion failure.
                              5 December 2012

===========================================================================

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

Product:           BIND
Publisher:         ISC
Operating System:  UNIX variants (UNIX, Linux, OSX)
                   Windows
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2012-5688  

Original Bulletin: 
   https://kb.isc.org/article/AA-00828

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A specific query can cause BIND nameservers using DNS64 to exit with a REQUIRE 
assertion failure.

CVE:                     CVE-2012-5688
Document Version:        2.0
Posting date:            04 Dec 2012
Program Impacted:        BIND
Versions affected:       9.8.0->9.8.4, 9.9.0->9.9.2
Severity:                Critical
Exploitable:             Remotely

Description:

   BIND 9 nameservers using the DNS64 IPv6 transition mechanism are
   vulnerable to a software defect that allows a crafted query to
   crash the server with a REQUIRE assertion failure.  Remote
   exploitation of this defect can be achieved without extensive
   effort, resulting in a denial-of-service (DoS) vector against
   affected servers.

   Please Note: Support for DNS64 was added to BIND 9 in version
   9.8.0.  Therefore BIND 9 versions prior to 9.8.0 cannot be
   affected by this bug.  Also, nameservers running versions 9.8.0
   and greater can only be affected if DNS64 is turned on using the
   "dns64" configuration statement. If you are not using DNS64 you
   are not at risk.

   For current information on which versions are actively supported,
   please see http://www.isc.org/software/bind/versions.

Impact:

   Any BIND 9 nameserver configured to use DNS64 is vulnerable to
   this defect and can be crashed by any client machine from which
   it accepts queries.

CVSS Score:  7.8

CVSS Equation:  (AV:N/AC:L/Au:N/C:N/I:N/A:C)

   For more information on the Common Vulnerability Scoring System
   and to obtain your specific environmental score please visit:
   http://nvd.nist.gov/cvss.cfm?calculator&adv&version=2&vector=(AV:N/AC:L/Au:N/C:N/I:N/A:C)

Workarounds:

   Only BIND 9 servers which are configured to use DNS64 are
   vulnerable.  For those servers, disallowing queries from untrusted
   clients (a recommended practice in any case) will slightly
   mitigate a server's exposure, but no workarounds are available
   which will completely protect an affected server against
   exploitation of this bug.  If you are using DNS64 either disable
   it or upgrade to a fixed version.

Active exploits: 

   No known active exploits.

Solution: 

   Upgrade to the patched release most closely related to your
   current version of BIND. These can all be downloaded from
   http://www.isc.org/downloads/all.

   BIND 9 version 9.8.4-P1
   BIND 9 version 9.9.2-P1

Acknowledgements: 

   ISC would like to thank BlueCat Networks for bringing this defect to our 
   attention.

Document Revision History:

   1.0 - 27 November 2012 Advance Notification to Phase One.
   1.1 - 03 December 2012 Notification to Phase Two and Phase Three
   2.0 - 04 December 2012 Notification to Phase Four (Public)

Related Documents:

   Japanese Translation:  https://kb.isc.org/article/AA-00832
   Spanish Translation:  https://kb.isc.org/article/AA-00834
   German Translation:  https://kb.isc.org/article/AA-00833

   See our BIND Security Matrix for a complete listing of Security
   Vulnerabilities and versions affected.

     http://www.isc.org/software/bind/security/matrix

   If you'd like more information on our Forum or product support
   please visit www.isc.org/software/guild or www.isc.org/support.
   Do you still have questions?  Questions regarding this advisory
   should go to security-officer@isc.org

ISC Security Vulnerability Disclosure Policy: 
   Details of our current security advisory policy and practice can
   be found here:

   https://www.isc.org/security-vulnerability-disclosure-policy

   This Knowledge Base article https://kb.isc.org/article/AA-00828
   is the complete and official security advisory document.  There
   is also a summary article located on our website and linking to
   here: https://www.isc.org/software/bind/advisories/cve-2012-5688

Legal Disclaimer: 

   Internet Systems Consortium (ISC) is providing this notice on
   an "AS IS" basis. No warranty or guarantee of any kind is expressed
   in this notice and none should be implied. ISC expressly excludes
   and disclaims any warranties regarding this notice or materials
   referred to in this notice, including, without limitation, any
   implied warranty of merchantability, fitness for a particular
   purpose, absence of hidden defects, or of non-infringement. Your
   use or reliance on this notice or materials referred to in this
   notice is at your own risk. ISC may change this notice at any
   time.  A stand-alone copy or paraphrase of the text of this
   document that omits the document URL is an uncontrolled copy.
   Uncontrolled copies may lack important information, be out of
   date, or contain factual errors.

(c) 2001-2012 Internet Systems Consortium

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