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from http://www.securityfocus.com/archive/1/389654
__Summary
Usually Firefox does not allow that an executable, non-image file gets
directly dragged to the desktop (e.g. by supplying malware.exe as the src of
an image tag). Instead Firefox creates a link to the file on the desktop.
If you create a hybrid of a gif image and a batch file you can trick
Firefox. Since the hybrid renders as a valid image, Firefox tries to copy
the image to the desktop when dropped. By creating the image dynamicly and
forcing the content type image/gif, the file can be of any extension (e.g.
image.bat or image.exe).
The windows batch file parser is pretty forgiving. It just ignores the first
line of "gif trash" and executes whatever you append to the end of the
hybrid file.
Since windows hides known file extensions by default, a user can only tell
that something went wrong by looking at the file icon, which is different of
course. If the user does not care or know what this different icon means, a
double click to view or edit the "image" he just dropped executes the batch
file instead.
__Proof-of-Concept
http://www.mikx.de/firedragging/
__Status
The bug is marked as fixed in bugzilla. Get a nightly build, compile on your
own or wait for Firefox 1.0.1.
2005-01-26 Vendor informed (bugzilla.mozilla.org #279945)
2005-01-31 Vendor confirmed bug
2005-02-03 Vendor fixed bug
2005-02-07 Public disclosure
__Summary
Usually Firefox does not allow that an executable, non-image file gets
directly dragged to the desktop (e.g. by supplying malware.exe as the src of
an image tag). Instead Firefox creates a link to the file on the desktop.
If you create a hybrid of a gif image and a batch file you can trick
Firefox. Since the hybrid renders as a valid image, Firefox tries to copy
the image to the desktop when dropped. By creating the image dynamicly and
forcing the content type image/gif, the file can be of any extension (e.g.
image.bat or image.exe).
The windows batch file parser is pretty forgiving. It just ignores the first
line of "gif trash" and executes whatever you append to the end of the
hybrid file.
Since windows hides known file extensions by default, a user can only tell
that something went wrong by looking at the file icon, which is different of
course. If the user does not care or know what this different icon means, a
double click to view or edit the "image" he just dropped executes the batch
file instead.
__Proof-of-Concept
http://www.mikx.de/firedragging/
__Status
The bug is marked as fixed in bugzilla. Get a nightly build, compile on your
own or wait for Firefox 1.0.1.
2005-01-26 Vendor informed (bugzilla.mozilla.org #279945)
2005-01-31 Vendor confirmed bug
2005-02-03 Vendor fixed bug
2005-02-07 Public disclosure
