Like a couple of its Fake AV predecessors, Mac Defender has a tendency to pop up when you least expect it, waving its virtual arms in a presumably critical warning about malware that has supposedly been found on your machine. Of course, it has a solution to your problem in the form of bogus antivirus software that actually lets loose a torrent of porn websites that automatically get loaded onto your computer. The number of victims was listed in the hundreds. The bug achieved brief notoriety in spring 2011, and was apparently spread by tricking people to open an image on a search engine. Mac Defender came across as a pretty convincing offer, according to several sources. Apple solved the problem through a software update.