The shtml.exe program in the FrontPage extensions package of IIS 4.0 and 5.0 allows remote attackers to determine the physical path of HTML, HTM, ASP, and SHTML files by requesting a file that does not exist, which generates an error message that reveals the path.
http://www.securityfocus.com/bid/1174
http://archives.neohapsis.com/archives/bugtraq/2000-05/0084.html