Blue Coat Systems WinProxy Host Header Stack Overflow Vulnerability

iDefense Security Advisory 01.05.06
http://www.idefense.com/intelligence/vulnerabilities/display.php?id=364
January 05, 2006

I. BACKGROUND

BlueCoat WinProxy is an Internet sharing proxy server designed for small
to medium businesses. In addition to Internet sharing Winproxy also
hosts a series of security, anti-spam and anti-spyware capabilities.

More information can be located from the vendors site at:

  http://www.winproxy.com/

II. DESCRIPTION

Remote exploitation of a buffer overflow vulnerability in Blue Coat
Systems Inc.'s WinProxy allows for the remote execution of arbitrary
code by attackers.
 
The vulnerability can be triggered by sending an overly long Host:
string to the web proxy service.

III. ANALYSIS

Exploitation of this vulnerability is trivial. An overly long header
directly overwrites the SEH handler for the frame allowing for control
over EIP.

IV. DETECTION

iDefense has confirmed this vulnerability in WinProxy 6.0. All previous
versions are suspected to be vulnerable.

V. WORKAROUND

Disabling the WinProxy web proxy protocol will prevent this attack.

VI. VENDOR RESPONSE

Blue Coat has released WinProxy 6.1a to address this vulnerability.

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-4085 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

12/07/2005  Initial vendor notification
12/08/2005  Initial vendor response
01/05/2006  Coordinated public disclosure

IX. CREDIT

This vulnerability was discovered by FistFuXXer.

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X. LEGAL NOTICES

Copyright © 2006 iDefense, Inc.

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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
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