
"If your files get encrypted, we’re not sure how dire a situation that is. It depends on the encryption and how the keys are handled. It’s possible that further research could lead to a method for decrypting files, and it’s also possible that won’t happen.
The best way of avoiding the consequences of ransomware is to maintain a good set of backups. Keep at least two backup copies of all important data, and at least one should not be kept attached to your Mac at all times. (Ransomware may try to encrypt or damage backups on connected drives.)"