Software Engineering Institute

Microsoft's Java VM is installed on Windows 98, NT, 2000, and xp. It is used by Internet Explorer and Outlook Express to execute Java applets.

The VM includes a class named "com.ms.osp.ospmrshl" that provides XML support to Java applets. This class exposes certain methods that are only intended to be accessed by trusted applets. However, the class does not check whether the applet is trusted before exposing these methods. Therefore, untrusted applets may access the methods and use them to execute arbitrary code on the client system.

The default configuration of Outlook Express 2002 and Outlook Express 6 opens HTML messages in the Restricted Sites zone, where Java applets are disabled. The same is true for Outlook Express 98 and 2000 if the Outlook Email Security Update has been applied. In these cases, the vulnerability described herein is not exploitable within Outlook Express.

This vulnerability may still be exploited by leading an Internet Explorer user to visit a web page containing a malicious Java applet.

A remote attacker may execute arbitrary code on a client running Internet Explorer or some configurations of Outlook Express.

Apply a patch

For more information, see:

http://www.microsoft.com/technet/security/bulletin/MS02-052.asp