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AUSCERT External Security Bulletin Redistribution
ESB-2007.0234 -- [Win]
Yahoo! Messenger AudioConf ActiveX Control buffer overflow vulnerability
10 April 2007
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AusCERT Security Bulletin Summary
---------------------------------
Product: Yahoo! Messenger
Publisher: US-CERT
Operating System: Windows
Impact: Execute Arbitrary Code/Commands
Access: Remote/Unauthenticated
CVE Names: CVE-2007-1680
Original Bulletin: http://www.kb.cert.org/vuls/id/388377
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US-CERT Vulnerability Note VU#388377
Yahoo! Messenger AudioConf ActiveX Control buffer overflow vulnerability
Overview
The Yahoo! Messenger AudioConf ActiveX control contains a buffer
overflow, which could allow a remote, unauthenticated attacker to
execute arbitrary code on a vulnerable system.
I. Description
Yahoo! Messenger is an instant messaging application. Yahoo! Messenger
includes several ActiveX controls. The AudioConf ActiveX control,
which is provided by yacscom.dll, contains a buffer overflow
vulnerability.
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
Apply an update
As specified in the Yahoo! Security Update, this issue is addressed
in versions of Yahoo Messenger from Mar 13th 2007 or later. Version
1.0.0.48 or higher of yacscom.dll contains the fix.
http://messenger.yahoo.com/security_update.php;_ylt=AkQgcpun6x0v49V3Uxj7PSnlLdMF?id=031207
Disable the YMailAttach ActiveX control in Internet Explorer
The Yahoo! AudioConf ActiveX control can be disabled in Internet
Explorer by setting the kill bit for the following CLSID:
{85A4A99C-8C3D-499E-A386-E0743DFF8FB7}
More information about how to set the kill bit is available in Microsoft
Support Document 240797. http://support.microsoft.com/kb/240797
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.
http://www.us-cert.gov/reading_room/securing_browser/#Internet_Explorer
Systems Affected
Vendor Status Date Updated
Yahoo, Inc. Vulnerable 9-Apr-2007
References
http://messenger.yahoo.com/security_update.php?id=031207
http://www.zerodayinitiative.com/advisories/ZDI-07-012.html
http://secunia.com/advisories/24742/
http://www.frsirt.com/english/advisories/2007/1219
http://securitytracker.com/alerts/2007/Apr/1017867.html
http://support.microsoft.com/kb/240797
http://www.us-cert.gov/reading_room/securing_browser/#Internet_Explorer
Credit
Thanks to Yahoo and ZDI for information that was used in this report.
Yahoo credits ZDI for reporting this vulnerability.
This document was written by Ryan Giobbi.
Other Information
Date Public 04/03/2007
Date First Published 04/09/2007 04:17:21 PM
Date Last Updated 04/09/2007
CERT Advisory
CVE Name CVE-2007-1680
Metric 10.21
Document Revision 9
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