Numerous installations of Microsoft ASP.NET are vulnerable to cross-site scripting (CSS), according to a recent post by Johannes Westerink to the BugTraq mailing list.
CSS leverages JavaScript and makes it possible to place a malicious URL in an e-mail or on a Web site, which if followed will compromise the user"s machine by various means, including exposing shares and/or retrieving data files such as cookies.
JavaScript can also be executed on a remote server using malicious URLs. There are numerous possible attacks; but for one common example, a 404 page may be generated with the added bonus of full path disclosure.
Westerink says he contacted MS about the issue six months ago but never got a reply.