Flaw in MicrosoftVM Could Enable System Compromise

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http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/bulletin/MS03-011.asp

 

Affected Software:

 

Versions of the Microsoft virtual machine (Microsoft VM) are identified by build numbers, which can be determined using the JVIEW tool as discussed in the FAQ. All builds of the Microsoft VM up to and including build 5.0.3809 are affected by these vulnerabilities

 

Technical description:

 

 

The Microsoft VM is a virtual machine for the Win32® operating environment. The Microsoft VM is shipped in most versions of Windows (a complete list is available in the FAQ), as well as in most versions of Internet Explorer.

 

The present Microsoft VM, which includes all previously released fixes to the VM, has been updated to include a fix for the newly reported security vulnerability. This new security vulnerability affects the ByteCode Verifier component of the Microsoft VM, and results because the ByteCode verifier does not correctly check for the presence of certain malicious code when a Java applet is being loaded. The attack vector for this new security issue would likely involve an attacker creating a malicious Java applet and inserting it into a web page that when opened, would exploit the vulnerability. An attacker could then host this malicious web page on a web site, or could send it to a user in e-mail.

 

Mitigating factors:

 

In order to exploit this vulnerability via the web-based attack vector, the attacker would need to entice a user into visiting a web site that the attacker controlled. The vulnerability themselves provide no way to force a user to a web site.

Java applets are disabled within the Restricted Sites Zone. As a result, any mail client that opened HTML mail within the Restricted Sites Zone, such as Outlook 2002, Outlook Express 6, or Outlook 98 or 2000 when used in conjunction with the Outlook Email Security Update, would not be at risk from the mail-based attack vector.

The vulnerability would gain only the privileges of the user, so customers who operate with less than administrative privileges would be at less risk from the vulnerability.

Corporate IT administrators could limit the risk posed to their users by using application filters at the firewall to inspect and block mobile code.