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                     Secunia Research 20/06/2008

      - XnView, NConvert, and GFL SDK Sun TAAC Buffer Overflow -

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Table of Contents

Affected Software....................................................1
Severity.............................................................2
Vendor's Description of Software.....................................3
Description of Vulnerability.........................................4
Solution.............................................................5
Time Table...........................................................6
Credits..............................................................7
References...........................................................8
About Secunia........................................................9
Verification........................................................10

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1) Affected Software 

* XnView 1.93.6 for Windows
* XnView 1.70 for Linux and FreeBSD
* NConvert 4.92
* GFL SDK 2.82

NOTE: Other versions may also be affected.

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2) Severity 

Rating: Highly critical
Impact: System access
Where:  From remote

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3) Vendor's Description of Software 

XnView:
"A software to view and convert graphic files, really simple to use!"

Product Link:
http://pagesperso-orange.fr/pierre.g/xnview/enhome.html

NConvert: 
"Come to discover NConvert, a batch utility to convert graphic files!"

Product Link:
http://pagesperso-orange.fr/pierre.g/xnview/en_nconvert.html

GFL SDK:
"GFL SDK is a free library (used by XnView) for developers who would
like to support graphics image formats easily."

Product Link:
http://pagesperso-orange.fr/pierre.g/xnview/engfl.html

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4) Description of Vulnerability

Secunia Research has discovered a vulnerability in XnView, NConvert,
and GFL SDK, which can be exploited by malicious people to compromise
a user's system.

The vulnerability is caused due to a boundary error when processing
the "format" keyword of Sun TAAC files. This can be exploited to
cause a stack-based buffer overflow by e.g. tricking a user into
viewing a specially crafted Sun TAAC file.

Successful exploitation allows execution of arbitrary code.

The vulnerability is confirmed in version 1.70 of XnView for Linux
and FreeBSD, XnView 1.93.6 for Windows, GFL SDK 2.82, and NConvert
4.92. Other versions may also be affected.

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5) Solution 

XnView:
The vulnerability is fixed in version 1.94 beta1.

NConvert and GFL SDK:
A fixed version is not currently available. Do not open untrusted Sun
TAAC files.

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6) Time Table 

28/05/2008 - Vendor notified.
29/05/2008 - Vendor response.
18/06/2008 - Vendor issues XnView 1.94 beta1.
20/06/2008 - Public disclosure.

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7) Credits 

Discovered by Stefan Cornelius, Secunia Research.

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8) References

The Common Vulnerabilities and Exposures (CVE) project has assigned 
CVE-2008-2427 for the vulnerability.

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9) About Secunia

Secunia offers vulnerability management solutions to corporate
customers with verified and reliable vulnerability intelligence
relevant to their specific system configuration:

http://corporate.secunia.com/

Secunia also provides a publicly accessible and comprehensive advisory
database as a service to the security community and private 
individuals, who are interested in or concerned about IT-security.

http://secunia.com/

Secunia believes that it is important to support the community and to
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security and reliability of software in general:

http://corporate.secunia.com/secunia_research/33/

Secunia regularly hires new skilled team members. Check the URL below 
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Secunia offers a FREE mailing list called Secunia Security Advisories:

http://secunia.com/secunia_security_advisories/ 

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10) Verification 

Please verify this advisory by visiting the Secunia website:
http://secunia.com/secunia_research/2008-24/

Complete list of vulnerability reports published by Secunia Research:
http://secunia.com/secunia_research/

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