Vulnerability Note VU#821156

Microsoft Internet Explorer long URL buffer overflow

Overview

Microsoft Internet Explorer is vulnerable to a buffer overflow when processing a long URL on a web site that uses HTTP 1.1 compression. This could allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system.

I. Description

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.

II. Impact

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.

III. Solution

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.

Systems Affected

Vendor	Status	Date Updated
Microsoft Corporation	Vulnerable	24-Aug-2006

References

http://www.microsoft.com/technet/security/advisory/923762.mspx
http://www.microsoft.com/technet/security/Bulletin/MS06-042.mspx
http://support.microsoft.com/?kbid=918899
http://www.w3.org/Protocols/rfc2616/rfc2616.html
http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.5
http://research.eeye.com/html/alerts/AL20060822.html
http://www.securityfocus.com/bid/19667

Credit

Thanks to Dejan Kovacevic of Bold Internet Solutions for reporting this vulnerability.

This document was written by Will Dormann.

Other Information

Date Public	08/22/2006
Date First Published	08/22/2006 04:39:45 PM
Date Last Updated	08/24/2006
CERT Advisory
CVE Name	CVE-2006-3869
US-CERT Technical Alerts
Metric	13.37
Document Revision	12

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Produced 2006 by US-CERT, a government organization
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