OK, in case you missed it the Mac community has just gotten it’s first taste of RandomWare! What’s RandomWare? It’s malicious software that once executed on your computer proceeds to encrypt it’s contents and require you pay to get the decryption key to recover your data. Our induction into this club came in the form of a compromised installer for the open source Transmission BitTorrent client. Details are available here among other places:
Now the good news is that unless you explicitly downloaded and installed Transmission 2.90 you’ve got absolutely nothing to worry about. Apple has already updated it’s Gatekeeper security files to block the software so make sure you’ve installed all recent OS X updates.
If you did recently install Transmission the article linked above will tell you how to know if you’ve been compromised and how to get rid of it. If you’ve already had the misfortune of having this piece of garbage inform you it wants money you could probably still get away without paying up by restoring your data from an earlier Time machine backup (you ARE doing Time Machine backups, right?!) You’d lose work done after that backup but save about $400.
It should be noted that (brace yourself) not all ransomware authors are honest or necessarily competent enough to be able to return your data to you (I know, shocking!) so even paying up may not always guarantee the safe return of your precious bits and bytes.
As to how to protect yourself in the future, the best advice is still to only download apps and updates from the original sources and never, EVER, EVER open attachments you were not expecting even if they arrive in your in-box from someone you know.