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                     Secunia Research 01/08/2012

              - Citrix Access Gateway Plug-in for Windows -
          - "nsepacom" ActiveX Integer 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 an integer overflow 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 a specially
crafted "Content-Length" HTTP response header.

Successful exploitation may allow 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-2011-2593 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/2012-26/

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

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