MS Security Bulletin MS02-013 (Version 2.0)

Thank you to eaglebtc for the links :)

Title: 04 March 2002 Cumulative VM Update

Released: 04 March 2002

Revised: 18 March 2002 (version 2.0)

Software: Microsoft Virtual Machine

Impact: Information Disclosure, run code of an attacker's choice

Max Risk: Critical

Reason for Revision:

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On March 4, 2002, Microsoft released the first version of this bulletin. On March 18, 2002, Microsoft re-released this bulletin to make customers aware of an additional vulnerability that is eliminated by the updated VM (Microsoft VM build 3805). Customers who have previously installed the new build do not need to take any additional action.

Issue:

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The Microsoft VM is a virtual machine for the Win32(r) operating environment. The Microsoft VM is available for Windows 95, Windows 98, ME, Windows NT(r) 4.0, Windows 2000, and Windows XP. It is also available as part of Internet Explorer 6 and earlier.

A new build of the VM (build 3805) is available, which eliminates two security vulnerabilities. The first vulnerability is the result of a flaw affecting how Java requests for proxy resources are handled. A malicious Java applet could exploit this flaw to re-direct web traffic once it has left the proxy server to a destination of the attacker's choice.

The second vulnerability is a new discovered variant of the "Virtual Machine Verifier" issue first discussed in MS99-045. Like most programming languages, the Java language provides the means to convert types by means of casting operations. Most commonly, these are used to convert data types, although other more complex type conversion is possible. A flaw exists in the security checks on casting operations within the Microsoft VM. A vulnerability results because it is possible for an attacker to exploit this flaw and use it to execute code outside of the sandbox. This code would execute as in the context of the user, and would only be limited by those constraints which govern the user herself.

The flaw only affects Java applets, it does not affect Java applications. To mount a successful attack, the malicious user would have to specially craft a Java applet at the binary level, post it on his site, and entice the intended target to visit his site.

Download: MS Java VM, build 3805 for 95, 98, Me, NT4, XP [All supported language versions included]