IIS XSS via 404 error

Summary
This IIS Server appears to vulnerable to one of the cross site scripting attacks described in MS02-018. The default '404' file returned by IIS uses scripting to output a link to top level domain part of the url requested. By crafting a particular URL it is possible to insert arbitrary script into the page for execution. The presence of this vulnerability also indicates that you are vulnerable to the other issues identified in MS02-018 (various remote buffer overflow and cross site scripting attacks...)
References