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

Vulnerability Note VU#159220

Original Release Date: 2006-07-07 | Last Revised: 2006-08-08


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.



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.


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.


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.

Vendor Information


Microsoft Corporation Affected

Notified:  July 07, 2006 Updated: August 08, 2006



Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.


Please see Microsoft Security Bulletin MS06-046.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

CVSS Metrics

Group Score Vector



This vulnerability was publicly reported by HD Moore.

This document was written by Will Dormann.

Other Information

CVE IDs: CVE-2006-3357
Severity Metric: 13.16
Date Public: 2006-07-02
Date First Published: 2006-07-07
Date Last Updated: 2006-08-08 19:23 UTC
Document Revision: 9

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