Specifically, it would allow the script to access files on the user s computer. This would enable the scripts to forward the contents of the files to the malicious user s web site. However, it would not allow him to change the files, delete them, or add news ones. For a detailed discussion of why script loaded from the user s computer would run in the Local Computer Zone, please consult the discussion of the Cache Bypass vulnerability in Microsoft Security Bulletin MS00-046 . Only files that can be opened in a browser window.
Examples are .txt, .htm or .js files.
Examples of file types that cannot be opened in a browser window include .dat, .doc, .exe, .jpg and other file types. This vulnerability has nothing to do with the Scriptlet technology per se. It results because of an implementation error in the Scriptlet Component, that results in it rendering any file as a scriptlet, rather than rendering only HTML files. The new variant involves an additional function with the same flaw. By design, a browser window can contain subwindows called frames, and the frames can reside in different domains for instance, one frame could display a page from a web site, while another shows the contents of a file on the local computer.