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Yahoo Messenger YMailAttach ActiveX Control Heap Corruption Vulnerability

12.15.06

BACKGROUND

Yahoo Messenger is a instant messaging application that allows users to chat online, share files, conduct PC to PC calls and more. More information can be found on the vendors site at:

http://messenger.yahoo.com/

DESCRIPTION

Remote exploitation of a heap corruption vulnerability in Yahoo Inc.'s Yahoo! Messenger could allow malicious web sites to execute arbitrary code with the privileges of the currently logged in user.

The vulnerability specifically lays with in the following ActiveX Control:

ProgID: YMMAPI.YMailAttach
Clsid: AA218328-0EA8-4D70-8972-E987A9190FF4
File: C:PROGRA~1YAHOO!COMMONymmapi.dll
Version: 2004.11.23.1

The overflow is triggered by setting the TextETACalculating property to an overly long string.

ANALYSIS

This vulnerability can be triggered by a malicious website. Users would be required to have a vulnerable version of the target software installed and be lured to a malicious site.

DETECTION

iDefense has confirmed the existence of this vulnerability in version 8.0 of Yahoo Instant Messenger. Version 7.5 has also been reported vulnerable. Previous versions are suspected vulnerable as well.

WORKAROUND

Users can set the kill bit for the target ActiveX control to block the control from loading within Internet Explorer.

VENDOR RESPONSE

Yahoo has addressed this vulnerability within version 2005.1.1.4 of their Messenger product. This version sets the kill bit for the affected control. More information can be found at the link shown below.

http://messenger.yahoo.com/security_update.php?id=120806

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2006-6603 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/ which standardizes names for security problems.

DISCLOSURE TIMELINE

10/26/2006 Initial vendor notification
12/15/2006 Initial vendor response
12/15/2006 Coordinated public disclosure

CREDIT

This vulnerability was reported to iDefense by Peter Vreugdenhil.

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LEGAL NOTICES

Copyright © 2006 Verisign, Inc.

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Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.