Firefox 1.0 allows remote attackers to modify Boolean configuration parameters
for the about:config site by using a plugin such as Flash, and the -moz-opacity
filter, to display the about:config site then cause the user to double-click at
a certain screen position.
This is an issue since flash will install itself with very little user input.
From the mozilla security advisory:
Plugins (such as flash) can be used to load privileged content into a frame.
Once loaded various spoofs can be applied to get the user to interact with the
privileged content. Michael Krax's "Fireflashing" example demonstrates that an
attacker can open about:config in a frame, hide it with an opacity setting, and
if the attacker can get the victim to click at a particular spot (design some
kind of simple game) you could toggle boolean preferences, some of which would
make further attacks easier.
The "firescrolling" example demonstrates arbitrary code execution (in this case
downloading a file) by convincing the user to scroll twice.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.