The problem is, having a server on the internet is painful because you have to be constantly on guard for patches - if not you'll get hacked sooner than later.
This was on a box that was firewalled and ssh was locked down. It was running an older kernel - that was probably my downfall.
I immediately shut down and rebuilt the droplet with a more modern kernel. It wasn't too hard because my site is (mostly) static with a simple custom service but is very discouraging to find that somebody has damaged your home project just to (I assume) make a small amount of money.
seriously, it's not that hard to keep a server uptodate