Yahoo Messenger YVerInfo.dll ActiveX Multiple Remote Buffer Overflow
iDefense Security Advisory 08.30.07
Aug 30, 2007
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.
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.
File: C:\Program Files\Yahoo!\Common\YVerInfo.dll
Stack based buffer overflows can be triggered through either the fvCom()
or info() methods of this class.
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.
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.
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
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
VIII. DISCLOSURE TIMELINE
08/21/2007 Initial vendor notification
08/21/2007 Initial vendor response
08/30/2007 Coordinated public disclosure
The discoverer of this vulnerability wishes to remain anonymous.
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Copyright =A9 2007 iDefense, Inc.
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