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Yahoo Messenger YVerInfo.dll ActiveX Multiple Remote Buffer Overflow Vulnerabilities

08.30.07

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 vendor's site at the following URL.

http://messenger.yahoo.com/

DESCRIPTION

Remote exploitation of multiple buffer overflow vulnerabilities in Yahoo Inc.'s Yahoo! Messenger 8.1 allows attackers to execute arbitrary code with the privileges of the currently logged in user.

When Yahoo Messenger 8.1 is installed, the following vulnerable ActiveX Control is registered on the system.

 ProgID: YVerInfo.GetInfo.1 Clsid: D5184A39-CBDF-4A4F-AC1A-7A45A852C883 File: C:Program FilesYahoo!CommonYVerInfo.dll Version: 2006.8.24.1 

Stack based buffer overflows can be triggered through either the fvCom() or info() methods of this class.

ANALYSIS

Exploitation allows attackers to execute arbitrary code with the privileges of the currently logged in user. Users would be required to have a vulnerable version of the target software installed and be lured to a malicious site.

It is important to note that functions within this class can only be called if the control believes it is being run from the yahoo.com domain. In order for this exploit to be triggered an attacker would either have to leverage a Cross-Site Scripting vulnerability in the yahoo.com domain, or be able to control the targeted user's DNS resolution for the domain.

DETECTION

iDefense has confirmed the existence of this vulnerability in version 8.1 of Yahoo Instant Messenger. Previous versions are suspected to be vulnerable as well.

WORKAROUND

Setting the kill bit for the vulnerable ActiveX control's CLSID will prevent these issues from be exploited within Internet Explorer.

VENDOR RESPONSE

Yahoo Inc. has addressed these vulnerabilities by releasing an updated version of Yahoo! Messenger. More information is available at the following URL.

http://messenger.yahoo.com/security_update.php?id=082907

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2007-4515 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

08/21/2007 Initial vendor notification
08/21/2007 Initial vendor response
08/30/2007 Coordinated public disclosure

CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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LEGAL NOTICES

Copyright © 2007 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.