Cryptowall is a variant of the old Cryptolocker Virus or Trojan horse that encrypts files on the compromised computer. It then asks the user to pay to have the files decrypted. We call that type of exploit Ransomware! The Department of Justice infiltrated the Cryptolocker servers and put up a website https://www.decryptcryptolocker.com/ to allow victims to decrypt their files for free.