CryptoLocker. WannaCry. Petya. Bad Rabbit. The ransomware threat isn’t going away anytime soon; the news brings constant reports of new waves of this pernicious type of malware washing across the world. It’s popular in large part because of the immediate financial payoff for attackers: It works by encrypting the files on your hard disk, then demands that you pay a ransom, frequently in Bitcoins, to decrypt them.