now it is malicious GIF files for MOZILLA
control your virussoftware because possibly you didn't scan gif files because who would care to put code behind a gif file (they did behind jpeg and mp3 files didn't they) so now they did and you will have to scan gif files because it can take over a mozilla browser under certain conditions.
Mozilla was said to be safe, but forget that. Nothing is safe anymore and it will just be a matter of time for the attacks to follow the market. You didn't hear about php worms untill last year, didn't you ?
Firefox 1.0.2, Thunderbird 1.0.2, and Mozilla Suite 1.7.6 address this and two other less serious bugs. Mozilla advisories are at:
http://www.mozilla.org/security/announce/mfsa2005-32.html http://www.mozilla.org/security/announce/mfsa2005-31.html http://www.mozilla.org/security/announce/mfsa2005-30.html
do not think you are safe because you are driving another car, the roads aren't safe whatever your car.