Ransomware is a piece of malware that encrypts files on your computer with strong encryption algorithms and then demands a ransom money in Bitcoin to decrypt the data so you can regain access to your encrypted files. Dubbed Koolova, the new strain of ransomware takes the infection to a whole new level of craziness. The most interesting one was Popcorn Time that decrypts victims files for free if they pass the infection on to other people. The only difference between the infections is that you don’t have to infect others to get free decryption key.
Source: https://thehackernews.com/2017/01/decrypt-ransomware-files.html