Blue Coat WinProxy Remote DoS Vulnerability

Credit: FistFuXXer
Risk: Medium
Local: No
Remote: Yes

CVSS Base Score: 7.5/10
Impact Subscore: 6.4/10
Exploitability Subscore: 10/10
Exploit range: Remote
Attack complexity: Low
Authentication: No required
Confidentiality impact: Partial
Integrity impact: Partial
Availability impact: Partial

Blue Coat WinProxy Remote DoS Vulnerability iDefense Security Advisory 01.05.06 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: II. DESCRIPTION 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. III. ANALYSIS 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 restarted. 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. IV. DETECTION iDefense has confirmed this vulnerability in WinProxy 6.0. Blue Coat has reported that previous versions are not affected. V. WORKAROUND iDefense is currently unaware of any workarounds for this issue. 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-2005-3187 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems. VIII. DISCLOSURE TIMELINE 10/12/2005 Initial vendor notification 10/12/2005 Initial vendor response 01/05/2006 Coordinated public disclosure IX. CREDIT FistFuXXer is credited with the discovery of this vulnerability. Get paid for vulnerability research Free tools, research and upcoming events X. LEGAL NOTICES Copyright © 2006 iDefense, Inc. Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please email customerservice (at) idefense (dot) com [email concealed] for permission. Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.

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