Secunia Research: Citrix Access Gateway Plug-in for Windows nsepacom ActiveX Control Buffer Overflow

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                     Secunia Research 01/08/2012

             - Citrix Access Gateway Plug-in for Windows -
         - "nsepacom" ActiveX Buffer Overflow Vulnerability -

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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 

* Citrix Access Gateway Plug-in for Windows version 9.3.49.5.

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 

"Citrix Access Gateway Plug-in is client software for Windows XP and
Windows Vista (32-bit) that enables secure connectivity through
Access Gateway, Enterprise Edition."

Product Link:
http://www.citrix.com/site/ss/downloads/details.asp?downloadId=
1535878&productId=15005

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4) Description of Vulnerability

Secunia Research has discovered a vulnerability in Citrix Access
Gateway Plug-in for Windows, which can be exploited by malicious
people to compromise a user's system.

The vulnerability is caused by a boundary error in the nsepacom
ActiveX control (nsepa.exe) when processing HTTP responses based on
the request via the "StartEpa()" method. This can be exploited to 
cause a heap-based buffer overflow via an overly long "CSEC" HTTP
response header.

Successful exploitation allows execution of arbitrary code.

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5) Solution 

No official solution is currently available.

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6) Time Table 

19/07/2011 - Vendor notified.
21/07/2011 - Vendor response.
20/01/2012 - Requested status update.
08/02/2012 - Vendor response, fix not scheduled.
09/05/2012 - Requested status update.
09/05/2012 - Vendor response, fix scheduled for June.
03/07/2012 - Requested status update.
21/07/2012 - Vendor response, fix delayed.
01/08/2012 - Public disclosure.

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7) Credits 

Discovered by Dmitriy Pletnev, Secunia Research.

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8) References

The Common Vulnerabilities and Exposures (CVE) project has assigned
CVE-2011-2592 for the vulnerability.

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9) About Secunia

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10) Verification 

Please verify this advisory by visiting the Secunia website:
http://secunia.com/secunia_research/2012-27/

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

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