News

Second Microsoft VM Flaw Found

• By Scott Bekker
• 03/22/2002

A second critical flaw was discovered in the Microsoft Virtual Machine that could allow a malicious user to create a Java applet that executes code on a user's machine outside the Java "sandbox."

This adds to a critical flaw that prompted Microsoft to issue the patch in the first place at the beginning of March. That flaw could allow an attacker to view information on a user's machine. The original flaw only affected Internet Explorer users browsing behind proxy servers, a category that includes most of the corporate world.

The more recently discovered vulnerability is a variant of the Virtual Machine Verifier bug that Microsoft addressed in a 1999 patch. An attacker must post the malicious Java applet on a Web site and entice a user to execute the applet for the attack to work. Once the applet runs, the only constraints on the attacker's ability to execute code is the user's privileges.

The Microsoft Virtual Machine is available for all current Windows clients back to Windows 95 and all versions of Internet Explorer.

The Microsoft VM figures prominently in the lawsuit Sun Microsystems recently filed against Microsoft.

Microsoft's security bulletin is located at http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/bulletin/MS02-013.asp.