Ransomware is a type of malware that attempts to extort money from a computer user by infecting and taking control of the victim’s machine. This kind of malware has typically been the domain of Windows users, but has made its way to OS X. The malware is a simple webpage using JavaScript to load 150 iframes that require confirmation to be dismissed. The address bar shows a URL clearly trying to fool users – fbi.gov.id657546456-3999456674.k8381.
Source: https://thehackernews.com/2013/07/fbi-themed-mac-os-x-ransomware-malware.html