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                         AUSCERT Security Bulletin

     Security Advisory for libpng-1.4.0 and earlier, 27 February 2010
                               24 March 2010


        AusCERT Security Bulletin Summary

Product:              libpng
Operating System:     UNIX variants (UNIX, Linux, OSX)
Impact/Access:        Denial of Service -- Remote with User Interaction
Resolution:           Patch/Upgrade
CVE Names:            CVE-2010-0205  
Member content until: Saturday, April  3 2010

Comment: It is expected that vendors who package libpng will update their
         packages shortly to reflect this fix.

Revision History:     March 24 2010: Added CVE Reference
                      March  4 2010: Initial Release


        The PNG Development Group has advised that libpng-1.4.0 and earlier are
        vulnerable to a denial of service bug.


        The PNG Development Group has made the following statement regarding
        the vulnerability:
        "Because of the efficient compression method used in Portable Network
        Graphics (PNG) files, a small PNG file can expand tremendously,
        acting as a "decompression bomb". Malformed PNG chunks can consume a
        large amount of CPU and wall-clock time and large amounts of memory,
        up to all memory available on a system.
        Eventually libpng would discover that the chunk was malformed or
        would run out of memory, abandon the chunk and return the allocated
        memory, so this is only a nasty Denial of Service (DoS) vulnerability
        that probably cannot be used to compromise a system." [1]


        The PNG Development Group has released libpng-1.4.1 which they state:
        "... have been revised to use less CPU time and memory. Libpng-1.4.1
        also provides functions that applications can use to further defend
        against such files" [1]


        [1] Security Advisory for libpng-1.4.0 and earlier, 27 February 2010

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:


Australian Computer Emergency Response Team
The University of Queensland
Qld 4072

Internet Email: auscert@auscert.org.au
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Comment: http://www.auscert.org.au/render.html?it=1967