Buffer overflow in FTP server in Microsoft IIS 3.0 and 4.0 allows local and sometimes remote attackers to cause a denial of service via a long NLST (ls) command.
When IIS 2 or 3 is upgraded to IIS 4, ism.dll is inadvertently left in /scripts/iisadmin, which does not restrict access to the local machine and allows an unauthorized user to gain access to sensitive server information, including the Administrator's password.