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AA-2008.0264                  AUSCERT Advisory

                        [Win][Netware][UNIX/Linux]
              Malformed CAB files may crash Sophos Anti-virus
                               6 August 2009
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        AusCERT Advisory Summary
        ------------------------

Product:              Sophos Anti-Virus for Windows
                      Sophos Anti-Virus for Windows NT/9x
                      Sophos Anti-Virus for OS X
                      Sophos Anti-Virus for Linux
                      Sophos Anti-Virus for UNIX
                      Sophos Anti-Virus for Unix and Netware
Operating System:     Windows
                      UNIX variants (UNIX, Linux, OSX)
                      Netware
Impact:               Denial of Service
Access:               Remote/Unauthenticated
CVE Names:            CVE-2008-6903
Member content until: Monday, January 19 2009

Revision History:     August    6 2009: Added CVE reference
                      December 22 2008: Initial Release


OVERVIEW:

      A vulnerability has been discovered in Sophos Anti-Virus which could
      allow a specially constructed CAB archive file to crash Sophos
      Anti-virus.


IMPACT:

      "When scanned, handcrafted fuzzed CAB archive files were not being 
      processed appropriately by the virus engine, so that a segmentation 
      fault could be caused. This fault is only caused when CAB archive 
      scanning is turned on.  Archive scanning is turned off with Sophos 
      Anti-virus default settings." [1]
      

MITIGATION:

      The vendor has advised that version 2.82.1 and above of the virus
      scanning engine for all current versions of Sophos Anti-virus resolves
      this issue.

      In cases where updates can not be done, disabling scanning of CAB archive
      files will also avoid this issue. Scanning of archive files is disabled
      by default.


REFERENCES:

      [1] Advisory: Sophos Anti-Virus fuzzed CAB archive vulnerability reported
          http://www.sophos.com/support/knowledgebase/article/50611.html

AusCERT has made every effort to ensure that the information contained
in this document is accurate.  However, the decision to use the information
described is the responsibility of each user or organisation. The decision to
follow or act on information or advice contained in this security bulletin is
the responsibility of each user or organisation, and should be considered in
accordance with your organisation's site policies and procedures. AusCERT
takes no responsibility for consequences which may arise from following or
acting on information or advice contained in this security bulletin.

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.
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