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Category:   Application (Generic)  >   Blue Coat WinProxy Vendors:   Blue Coat Systems
Blue Coat WinProxy Host Header Buffer Overflow Lets Remote Users Execute Arbitrary Code
SecurityTracker Alert ID:  1015441
SecurityTracker URL:
CVE Reference:   CVE-2005-3187, CVE-2005-4085   (Links to External Site)
Date:  Jan 5 2006
Impact:   Denial of service via network, Execution of arbitrary code via network, User access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 6.0
Description:   iDEFENSE reported a vulnerability in Blue Coat WinProxy. A remote user can cause denial of service conditions. A remote user can also execute arbitrary code on the target system.

A remote user can submit a specially crafted HTTP request that is approximately 32,768 bytes long to cause the WinProxy service to crash [CVE-2005-3187].

A remote user can submit a specially crafted HTTP header 'Host' parameter value to trigger a buffer overflow and execute arbitrary code on the target system [CVE-2005-4085].

The vendor was notified on October 12, 2005 [CVE-2005-3187] and December 7, 2005 [CVE-2005-4085].

The original advisories are available at:

Impact:   A remote user can execute arbitrary code on the target system.

A remote user can cause the target service to crash.

Solution:   The vendor has issued a fixed version (6.1a).
Vendor URL: (Links to External Site)
Cause:   Boundary error
Underlying OS:  Windows (Any)

Message History:   This archive entry has one or more follow-up message(s) listed below.
Feb 17 2006 (ProxyAV is Affected) Blue Coat WinProxy Host Header Buffer Overflow Lets Remote Users Execute Arbitrary Code
Blue Coat has issued a fix for ProxyAV, which is also affected by this vulnerability.

 Source Message Contents

Subject:  iDefense Security Advisory 01.05.06: Blue Coat WinProxy Remote DoS

Blue Coat WinProxy Remote DoS Vulnerability

iDefense Security Advisory 01.05.06
January 05, 2006


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:


Remote exploitation of a design error in Blue Coat Systems Inc.'s
WinProxy allows attackers to cause a denial of service (DoS) condition.

The vulnerability specifically exists due to improper handling of a long
HTTP request that is approximately 32,768 bytes long. When such a
request occurs, the process will crash while attempting to read past the
end of a memory region.


Successful exploitation requires an attacker to send a specially
constructed HTTP request to the WinProxy server on TCP port 80. This
will lead to a crash of the server and it will be unusable until it is

This vulnerability may only be utilized by attackers who have access to
the network segment that contains the listening daemon, which in some
cases is a private local area network.


iDefense has confirmed this vulnerability in WinProxy 6.0. Blue Coat has
reported that previous versions are not affected.


iDefense is currently unaware of any workarounds for this issue.


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


The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-3187 to this issue. This is a candidate for inclusion in
the CVE list (, which standardizes names for
security problems.


10/12/2005  Initial vendor notification
10/12/2005  Initial vendor response
01/05/2006  Coordinated public disclosure


FistFuXXer is credited with the discovery of this vulnerability.

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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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There are no warranties with regard to this information. Neither the
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