This is not a virus, but rather a method to exploit a security vulnerability in the Microsoft Virtual Machine. This vulnerability arises as the ByteCode verifier in the Microsoft Virtual machine does not correctly check for the presence of certain malformed code when a Java applet is loaded. Attackers could exploit this vulnerability by creating malicious Java applets and inserting them into web pages. These web pages could be hosted on a site by a malicious web master, or could be sent to users as an attachment. To read more about this issue, and to download the necessary patches, please visit: