Rather than a ranking of the most widespread viruses, or those that have caused most infections, these viruses are ones that deserve mention for standing out from the more than 24 million new strains of malware that emerged.
Police virus: This strain of malware caused most headaches for users and IT departments alike. It purports to show a message from the police telling users that their computer has been blocked – which it has – because they have supposedly downloaded illegal material. To recover their systems, users are asked to pay a fine. The most recent versions even show images taken with the user's webcam, making the scam all the more realistic.
Flame: A close relative of Stuxnet, Flame is one of the most powerful cyber-war tools created so far, and infections have been focused primarily in the Middle East.
Flashback: A bot that breaks away from the norm of infecting Windows and targets Apple systems and attacks thousands of Mac computers around the world. Since it appeared, Mac users are no longer quite as relaxed about security as they once were.
Zeus: A Trojan that steals information from users of online banking services. This family of malware has been known for some time, yet it continues to spread. However this year new variants were detected, which in addition to infecting computers, compromise security on smartphones (Android, BlackBerry, Symbian), targeting those banks that send information via cellphone to customers as an additional security measure.
Koobface: The most mendacious malware of the year, spent the whole of 2012 spreading endless lies on social networks in order to infect users. In one attack it related a spurious story about President Obama having punched someone who racially insulted him. So beware of sensational stories on social media, this is a favorite trick of cyber-crooks.
BlackHole Exploit kit: One of the most popular kits for creating malware over the last year. It exploits numerous security holes to install and uses all types of exploits, particularly Java and Adobe.
DarkAngle: A fake antivirus that poses as Panda CloudAntivirus. It takes advantage of the renown of Panda Security's free cloud antivirus to infect as many computers as possible.
Ainslot.L: When it infects, the Ainslot.L bot scans computers and removes any other bots it finds.
Kuluoz: A worm that refers to things supposedly bought only and then infects computers. The worm arrives in an email that looks as though it has been sent from FedEx, and tells users they have a parcel to collect.