Trend Micro is warning small businesses about a new kind of ransomware called "Fairware" which infects Linux servers. If a business did not have its data backed up offline, it could lose everything, and the ransom extortionist could threaten to disclose consumer PII if the business did not pay.
The story is here. I don't know how well other services, like SiteLock, can protect against this hazard.
Since Linux is targeted, it sounds feasible that a similar kind of malware could be developed for MacOS.
Webroot is offering a seminar on encrypting ransomware on Sept. 7, online, for corporate IT security people, here.