(MacSpy isn’t ransomware, but seems to have been developed by the same author, and both are offered as as-a-service malware.)
Zeljka Zorz for HelpNet Security: Two Mac malware-as-a-Service offerings uncovered. According to HelpNet ‘Patric Wardle’s RansomWhere? tool can also stop MacRansomware from doing any damage.’
Rommel Joven and Wayne Chin Yick Low, for Fortinet: MacRansom: Offered as Ransomware as a Service
Fortinet notes that “Nevertheless, we are still skeptical of the author’s claim to be able to decrypt the hijacked files, even assuming that the victims sent the author an unknown random file…”
AlienVault: MacSpy: OS X RAT as a Service
Roland Dela Paz describes for Fortinet how Nemucod, much spammed malware already well-known for downloading malware including (recently) Teslacrypt, now has the ability to drop ransomware directly (i.e. from its own body) including the ransom note and a batch file to initiate the encryption.
Nemucod Adds Ransomware Routine
The good news is that the ransomware isn’t as effective as the ransom note tries to persuade the victims: not yet, anyway. It’s not the case that ‘Nobody can help you but us.’ That doesn’t mean this will always be the case, though.
Dela Paz notes some resemblance between this ransomware and KeyBTC but notes that it can’t be confirmed at present that there is a direct relationship.