The FBI Virus is also referred as Greendot virus, Citadel Reventon disguise itself as FBI, and if you want to access your computer in allotted time of 48-72 hrs then you have to pay the penalty of $100, $200 or more using Moneypak Card.
FBI virus on Mac Locks the Safari Browser and gives you warning, you cannot close safari to exit it.
2. From the drop down Menu click on Reset Safari..
3. Select all the check box and click on Reset.