In order for IE to parse a local file as a html document the filename extension must be associated with html documents (normally .htm and .html). Also html code must be found somewhere in the beginning of the file (IE will only scan a certain amount of bytes in the file). This is good security because several types of userdata is stored in local files (cookies, favorites/bookmarks, application userdata etc). The problem is that IE can be tricked into thinking that a local file is a html document regardless of file extension. Press READ MORE for further info. The trick is to simply add a dot "." when linking to a local filename. If we link to a file with the .txt extension then we must add " ." instead as of patch MS02-023. To test this behaviour simply create a file called c:/test.txt with some html code in it. Now compare the difference in parse behaviour by typing the following in the adress field: about:test.txt .

and compare it with:

about:test.txt Source Link: Security Focus
Direct Link: IE Dot Bug