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             AUSCERT External Security Bulletin Redistribution

                          ESB-2007.0234 -- [Win]
 Yahoo! Messenger AudioConf ActiveX Control buffer overflow vulnerability
                               10 April 2007


        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


	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

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 or higher of yacscom.dll contains the fix.

	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:


	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.

Systems Affected

	Vendor        Status        Date Updated
	Yahoo, Inc.   Vulnerable    9-Apr-2007




	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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