EvilQuest ransomware spread through macOS pirate applications
you need to watch what you download! the App Store is fine but that torrent may not be. The malware spreads on hard drive and after a few days, it activates and begins encrypting files.
Most significantly, the ransomware will hold your Mac hostage. It encrypts files asking for $50 to unlock them.It’s not yet clear how severe the encryption is or what the solution is.
More details here