Apple has already shut down the ransomware
[http://techcrunch.com/2016/03/07/apple-has-shut-down-the-first-fully-functional-mac-os-x-ransomware/?ncid=rss]
found in the Transmission torrent client. You can easily prevent this from
happening to you in the future by adding a Hazel rule to your downloads folder,
which will automatically determine the checksum, so