A different hypothesis on the tor-talk list was a piece of ransomware that generates a hidden service per victim:
https://lists.torproject.org/pipermail/tor-talk/2016-Februar...
https://lists.torproject.org/pipermail/tor-talk/2016-Februar...
At the moment we get hundreds of Locky mails per day.
There is a huge spike in ransomware at the moment. And all ransom has to be paid via a tor location.
IIRC last time I checked the Word doc on virustotal it was picked up 22/55.
Fortunately at least AV did pick up the payload when a user let the macro run...
Edit, ran it by virustotal again and got 28/55