Multiple Vulnerabilities in Yahoo! Messenger New

Multiple security vulnerabilities exist in the Yahoo! Messenger IM client that may allow an attacker to execute arbitrary code with the privileges of the victim user.

Issue

Yahoo! Messenger is a widely used program for communicating with other users over the Internet. On May 27, 2002, a buffer overflow and a URL validation vulnerability were discovered in the Yahoo! Messenger client for Microsoft Windows. Details of each vulnerability follow:

Yahoo! Messenger contains a buffer overflow in the URI handler
The buffer overflow occurs during the processing of the Yahoo! Messenger URI handler (ymsgr:). This URI handler is installed at the system level for applications that use the underlying operating system when processesing URIs (such as Microsoft Internet Explorer, Netscape Navigator 6, Microsoft Outlook, or the command shell). A URI can be sent by another Yahoo! Messenger user in a message, embedded in a web site, or sent in an HTML-renderable email message.

Yahoo! Messenger "addview" function allows for the automatic execution of malicious script contained in web pages
A vulnerability exists in the Yahoo! Messenger "addview" function that permits a remote attacker to execute arbitrary script and HTML in the Internet security zone of the local machine. The "addview" function is only supposed to accept view information from Yahoo! servers. However, an attacker can send malicious script and HTML to the client using the Yahoo! URL redirection service. This script or HTML is interpreted by the Yahoo! Messenger client and is displayed in the client's web browser.

These vulnerabilities were resolved in Yahoo! Messenger version 5,0,0,1065, released May 22, 2002; however, a bug in the distribution server may have inadvertently installed Yahoo! Messenger version 5,0,0,1036 on systems that downloaded Yahoo! Messenger after May 22, 2002. The bug in the distribution server has since been resolved.

Affected Products

• Yahoo! Messenger version 5,0,0,1064 and prior for Microsoft Windows

Solution

Yahoo! released a fixed version of Yahoo! Messenger (5,0,0,1065) in the United States and began issuing a patch (5,0,0,1066) via the AutoUpdater to address this issue. All users should upgrade to version 5,0,0,1065 or later. Users with versions prior to 5,0,0,1066 that have "Auto Update" enabled will receive a message informing them that an upgrade is available. All users should accept this upgrade.

Click here to upgrade now

Further Details

Source: CERT Coordination Center

Reference: Yahoo!, Inc.

Updated: June 7, 2002

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