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CERT Coordination Center

Microsoft Java implementation allows execution of malicious code

Vulnerability Note VU#140898

Original Release Date: 2002-10-11 | Last Revised: 2003-08-13


A class in Microsoft's Java virtual machine (VM) does not properly validate trusted applets, allowing untrusted applets to exploit native methods and execute arbitrary code.


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 "" 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.


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For more information, see:

Vendor Information


Microsoft Corporation Affected

Notified:  October 10, 2002 Updated: October 11, 2002



Vendor Statement


Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.


The CERT/CC has no additional comments at this time.

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

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Thanks to Jouko Pynnonen for reporting this vulnerability.

This document was written by Shawn Van Ittersum.

Other Information

CVE IDs: CVE-2002-0865
Severity Metric: 19.85
Date Public: 2002-09-09
Date First Published: 2002-10-11
Date Last Updated: 2003-08-13 19:45 UTC
Document Revision: 6

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