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                     Secunia Research 23/09/2005

           - 7-Zip ARJ Archive Handling Buffer Overflow -

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Table of Contents

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

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1) Affected Software 

7-Zip Version 3.13, 4.23, and 4.26 BETA

Other versions may also be affected.

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2) Severity 

Rating: Moderately Critical
Impact: System access
Where:  Remote

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3) Description of Vulnerability

Secunia Research has discovered a vulnerability in 7-Zip, which can
be exploited by malicious people to compromise a user's system.

The vulnerability is caused due to a boundary error when handling an
ARJ block that is larger than 2600 bytes. This can be exploited to 
cause a stack-based buffer overflow when a specially crafted ARJ file 
is opened.

Successful exploitation allows arbitrary code execution.

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4) Solution 

The vulnerability has been fixed in version 4.27 BETA.

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5) Time Table 

05/09/2005 - Initial vendor notification.
05/09/2005 - Initial vendor reply.
21/09/2005 - Vendor released fixed version.
23/09/2005 - Public disclosure.

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6) Credits 

Discovered by Tan Chew Keong, Secunia Research.

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7) References

No references available.

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8) About Secunia 

Secunia collects, validates, assesses, and writes advisories regarding 
all the latest software vulnerabilities disclosed to the public. These 
advisories are gathered in a publicly available database at the 
Secunia website: 

http://secunia.com/ 

Secunia offers services to our customers enabling them to receive all 
relevant vulnerability information to their specific system 
configuration. 

Secunia offers a FREE mailing list called Secunia Security Advisories: 

http://secunia.com/secunia_security_advisories/ 

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9) Verification 

Please verify this advisory by visiting the Secunia website:
http://secunia.com/secunia_research/2005-45/advisory/ 

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

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