The year 2015 has been witness to some of the most dangerous computer viruses in recent memory. The three viruses that have caused the most damage are the ransomware virus Cryptowall, the K7 Antivirus software virus, and the Babyshop virus.

Cryptowall is a ransomware virus that encrypts the data on a computer, making it inaccessible to the user, and then demands a ransom payment in order to decrypt the data. The virus first appeared in late 2013, but it has become increasingly prevalent in 2015. In May 2015, the FBI issued a warning that Cryptowall had caused more than $18 …