A vulnerability exists in Microsoft IIS 4 and 5 such that an attacker visiting an IIS web site can execute arbitrary code with the privileges of the IUSR_machinename account. This vulnerability is referred to as the "Web Server Folder Directory Traversal" vulnerability. This vulnerability has characteristics similar to vulnerabilities that have been widely exploited in the past. Unless remedial action is taken, we believe it is likely that systems with this vulnerability will be compromised.