Standalone Macromedia Flash Player 5.0 allows remote attackers to save arbitrary files and programs via a .SWF file containing the undocumented "save" FSCommand.
http://www.securityfocus.com/bid/4320
http://www.securityfocus.com/archive/1/262990
http://www.macromedia.com/support/flash/ts/documents/fs_save.htm