Vulnerability Note VU#159220

Microsoft Internet Explorer vulnerable to heap overflow via the HTML Help Control "Image" property

Overview

The HTML Help ActiveX control contains a heap overflow vulnerability. This may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system.

I. Description

ActiveX

ActiveX is a technology that allows programmers to create reusable software components that can be incorporated into applications to extend their functionality. Internet Explorer is a common Windows application that makes use of ActiveX controls.

HTML Help Control

The HTML Help Control (HHCtrl Object) is a Windows ActiveX control that provides the ability to view HTML help files. The HHCtrl Object is included in the file hhctrl.ocx and provides the ProgID (Programmatic Identifier) of Internet.HHCtrl.

The problem

The HHCtrl Object contains a heap overflow vulnerability when the Image property of the control is set. When the Image property is set multiple times, the heap memory can be corrupted.

II. Impact

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

III. Solution

Apply an update

This vulnerability is addressed in Microsoft Security Bulletin MS06-046.

Disable ActiveX

Disabling ActiveX controls in the Internet Zone (or any zone used by an attacker) appears to prevent exploitation of this vulnerability. Instructions for disabling ActiveX in the Internet Zone can be found in the "Securing Your Web Browser" document and the Malicious Web Scripts FAQ.

Systems Affected

Vendor	Status	Date Notified	Date Updated
Microsoft Corporation	Vulnerable	8-Aug-2006

References

http://www.microsoft.com/technet/security/bulletin/ms06-046.mspx
http://www.us-cert.gov/reading_room/securing_browser/#Internet_Explorer
http://browserfun.blogspot.com/2006/07/mobb-2-internethhctrl-image-property.html
http://osvdb.org/26835
http://secunia.com/advisories/20906/

Credit

This vulnerability was publicly reported by HD Moore.

This document was written by Will Dormann.

Other Information

Date Public:	2006-07-02
Date First Published:	2006-07-07
Date Last Updated:	2006-08-08
CERT Advisory:
CVE-ID(s):	CVE-2006-3357
NVD-ID(s):	CVE-2006-3357
US-CERT Technical Alerts:
Metric:	13.16
Document Revision:	8

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Produced 2006 by US-CERT, a government organization
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