Vulnerability Note VU#932217

Yahoo! Webcam view utilities ActiveX control vulnerable to arbitrary code execution

Overview

The Yahoo! Webcam view utilities ActiveX control contains a stack buffer overflow, which can allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system.

I. Description

Yahoo! Webcam is a component of Yahoo! Messenger that allows users to chat via webcams over a network. Yahoo! Webcam Viewer includes an ActiveX control provided by the file ywcvwr.dll . This ActiveX control contains a stack buffer overflow vulnerability in the Server property.

We are aware of publicly available exploit code for this 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

This issue is addressed in Yahoo! Messenger 8.1. If you are unable to upgrade, please consider the following workarounds:

Disable the Yahoo! Messenger ActiveX control in Internet Explorer

The vulnerable ActiveX control can be disabled in Internet Explorer by setting the kill bit for the following CLSID:

(

9D39223E-AE8E-11D4-8FD3-00D0B7730277

)

More information about how to set the kill bit is available in Microsoft Support Document 240797. Alternatively, the following text can be saved as a .REG file and imported to set the kill bit for this control:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{9D39223E-AE8E-11D4-8FD3-00D0B7730277}]

"Compatibility Flags"=dword:00000400

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 Notified	Date Updated
Yahoo, Inc.	Vulnerable	8-Jun-2007

References

http://research.eeye.com/html/alerts/zeroday/20070606.html
http://secunia.com/advisories/25547/
http://messenger.yahoo.com/security_update.php?id=060707

Credit

This issue was reported by eEye Digital Security in EEYEZD-20070606.

This document was written by Chris Taschner.

Other Information

Date Public:	2007-06-07
Date First Published:	2007-06-08
Date Last Updated:	2007-06-11
CERT Advisory:
CVE-ID(s):
NVD-ID(s):
US-CERT Technical Alerts:
Metric:	15.53
Document Revision:	13

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Produced 2007 by US-CERT, a government organization
Disclaimers and copyright information

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