MS Commercial Internet System 2.0/2.5,IIS 4.0,Proxy Server 2.0,Site Server Commerce Edition 3.0 UNC Mapped Virtual Host Vulnerability
source: https://www.securityfocus.com/bid/1081/info
If a virtual host root is mapped to a UNC share, a backward slash "\" appended to an ASP or HTR extension in a URL request to that virtual host will cause Microsoft Internet Information Server to transmit full source code of the file back to a remote user. Files located on the local drive where IIS is installed is not affected by this vulnerability.
http://target/file.asp\