It's not that hackers don't look for weaknesses in FF. It's just that if you tailor your virus to IE your number of targets is currently higher. It's similar to choosing whether to go fishing in a pond or a salmon farm. One has some fish there and you may catch a few with your fishing rod, the other you don't even need the rod because you can just use you hands.There's weaknesses in every browser. IE is susceptible in the same way that there are no viruses for macs, cuz IE was most popularly used for the longest time. If this becomes so popular that most people reject it and go for FF, we'll find weaknesses in that too. If you know any hackers, they can be fucking brilliant and will always find a way to mess with your computer. Don't try to pretend there are efficient ways around that in using different browsers