*Update: POC located @ k-otik.com
Multiple Vulnerabilities in Microsoft ASN.1 Library
Affects systems: windows XP, windows NT, Windows NT TSE, Windows server 2003.
Description: Integer arithmetic errors create the possibility for some friendly fellow to overflow your buffers via encrytion and authentication services(Any service that uses the ASN.1 Library) and execute code based on the privleges of the exploited service(in most cases system).
Solution: Patch from Microsoft
Topsight.net
http://www.topsight.net/article.php/20040210202400107