http://secunia.com/Internet_Explorer...oofing _Test/
Description:
hahahahahahahahahaha has identified a vulnerability in Internet Explorer, allowing malicious web sites to spoof the file extension of downloadable files.
The problem is that Internet Explorer can be tricked into opening a file, with a different application than indicated by the file extension. This can be done by hahahahahading a CLSID in the file name. This could be exploited to trick users into opening "trusted" file types which are in fact malicious files.