Cumulative IE patch for malicious cookies
'Critical', MS says
A fairly serious flaw in Internet Explorer which would enable a malicious Web page or e-mail to drop a cookie containing an HTML script on a victim's machine and run it in the 'Local Computer' zone rather than the Internet zone to avoid restrictions has just been patched.
The script would run with the user's level of permission, and could therefore do considerable damage depending on its design. The problem behind it is essentially an oversight by MS programmers, who failed to realize that once a cookie is stored locally, it's no longer restricted to the Internet zone, where, presumably, scripts and plugins should operate safely.
Also patched is an item more irritating than dangerous, in which an object tag in a Web page or an e-mail is improperly executed outside the Internet zone and calls an executable on the local machine, as we reported here.
In this case the file name and path must be known, so only programs in default locations can reasonably be activated. MS says that parameters can't be passed to the executable, so there's nothing terribly dangerous here.
We've had anecdotal reports that the MS patch fails to fix this on a few systems, and we'd be happy to hear from other readers if they're having problems with it. The above-linked article contains a sample script which can be used to test the patch. Just make sure the path to calc.exe is the same on your system, or edit the path in the script as needed.
The patches for IE 6; 5.5 SP-2; 5.5 SP-1; and 5.01 SP-2 for Win-2K and NT are located here. ®