Software Engineering Institute

Microsoft Internet Explorer 6 Service Pack 1 on Windows 2000 and Windows XP SP1 contains a vulnerability when viewing a web site using the HTTP 1.1 protocol. If the web site uses HTTP 1.1 compression and contains an overly long URL, a buffer overflow can occur.

Note that this vulnerability was introduced with the first release of the MS06-042 updates on August 8, 2006.

By convincing a user to view a specially crafted HTML document (e.g., a web page, an HTML email message, or an email attachment), an attacker could execute arbitrary code with the privileges of the user. The attacker could also cause Internet Explorer (or the program using the WebBrowser ActiveX control) to crash.

Apply an update
This vulnerability is addressed in Microsoft Security Bulletin MS06-042 version 2.0.

Disable Active Scripting

This vulnerability can be mitigated by disabling Active Scripting, as specified in the "Securing Your Web Browser" document. While this does not remove the vulnerability, it does block known techniques to exploit this vulnerability to execute arbitrary code.

Disable HTTP 1.1

This vulnerability can be mitigated by disabling HTTP 1.1, as specified in Microsoft Security Advisory 923762.