There is a buffer overflow in the remote IIS web server. It is possible to overflow the remote Web server and execute commands as the SYSTEM user. At attacker may make use of this vulnerability and use it to gain access to confidential data and/or escalate their privileges on the Web server. See http://www.eeye.com/html/Research/Advisories/AD20010501.html for more details.

See http://www.microsoft.com/technet/security/bulletin/ms01-023.mspx