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. Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp Free tools, research and upcoming events http://labs.idefense.com 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.