Yahoo Messenger YVerInfo.dll ActiveX Multiple Remote Buffer Overflow Vulnerabilities

Advisory Text :

I. 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/
II. 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 Files\Yahoo!\Common\YVerInfo.dll
Version: 2006.8.24.1

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

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

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

The discoverer of this vulnerability wishes to remain anonymous.

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X. LEGAL NOTICES

Copyright © 2007 iDefense, Inc.

Permission is granted for the redistribution of this alert electronically.
It may not be edited in any way without the express written consent of
iDefense. If you wish to reprint the whole or any part of this alert in any
other medium other than electronically, please e-mail customer service for
permission.

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.

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Yahoo Messenger YVerInfo.dll ActiveX Multiple Remote Buffer Overflow Vulnerabilities