There is a memory corruption vulnerability with GIF file processing in
Microsoft GDI+ that can be used to crash a vulnerable application and
potentially execute arbitrary code.

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#The vulnerability#
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The vulnerability is caused due to improper handling of graphic
control extension when processing malformed GIF files. The
vulnerability can be triggered if a large number of extension markers
(0x21) followed by unknown labels is found when processing a GIF file.

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#Impact#
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This vulnerability can be used to corrupt memory of any application
utilizing GDI+ for GIF file decoding if it is used to open a malformed
GIF file. This could lead to code execution with the privileges of the
user running the vulnerable application.

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#References#
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http://ifsec.blogspot.com/2008/09/windows-gdi-gif-memory-corruption.html 
http://www.zerodayinitiative.com/advisories/ZDI-08-056/ 
http://www.microsoft.com/technet/security/bulletin/ms08-052.mspx 
http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-3013