The execCommand method in Microsoft Internet Explorer 6.0 SP2 allows remote attackers to bypass the "File Download - Security Warning" dialog and save arbitrary files with arbitrary extensions via the SaveAs command.
https://exchange.xforce.ibmcloud.com/vulnerabilities/18181
http://www.kb.cert.org/vuls/id/743974
http://www.frsirt.com/exploits/20041119.IESP2Unpatched.php
http://securityreason.com/securityalert/3220
http://secunia.com/advisories/13203/
http://archives.neohapsis.com/archives/bugtraq/2004-11/0260.html