Vulnerability Note VU#906777

IncrediMail IMMenuShellExt ActiveX control stack buffer overflow vulnerability

Overview

The IncrediMail IMMenuShellExt ActiveX control contains a stack buffer overflow, which can allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system.

I. Description

IncrediMail is an email application that includes animations and 1000's of emoticons. IncrediMail comes with an ActiveX control called IMMenuShellExt, which is provided by the file ImShExt.dll. This ActiveX control contains a stack buffer overflow vulnerability in the DoWebMenuAction() method.

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

We are currently unaware of a practical solution to this problem. Please consider the following workarounds

Disable the IMMenuShellExt ActiveX control in Internet Explorer

The vulnerable ActiveX control can be disabled in Internet Explorer by setting the kill bit for the following CLSID:

{F8984111-38B6-11D5-8725-0050DA2761C4}

More information about how to set the kill bit is available in Microsoft Support Document 240797. Alternatively, the following text can be saved as a .REG file and imported to set the kill bit for this control:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{F8984111-38B6-11D5-8725-0050DA2761C4}]

"Compatibility Flags"=dword:00000400

Disable ActiveX

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

Systems Affected

Vendor	Status	Date Notified	Date Updated
IncrediMail Ltd.	Vulnerable	4-Apr-2007

References

http://www.us-cert.gov/reading_room/securing_browser/#Internet_Explorer
http://support.microsoft.com/kb/240797

Credit

This vulnerability was reported by Will Dormann of CERT/CC.

This document was written by Will Dormann.

Other Information

Date Public:	2007-04-26
Date First Published:	2007-04-26
Date Last Updated:	2007-04-26
CERT Advisory:
CVE-ID(s):	CVE-2007-1683
NVD-ID(s):	CVE-2007-1683
US-CERT Technical Alerts:
Metric:	2.07
Document Revision:	12

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Produced 2007 by US-CERT, a government organization
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