I've been tied up the last few days, so I missed this thread update. John is mostly correct in his assertions, as is Marc. The way the ransomware is propogated, the Aholes who host it do everything to conceal/provide false trails to it's origin. In many cases, they claim "Russian hackers", even after numerous security luminaries pointed out that the CIA uses numerous methods to attribute their own BS to their enemy du-jour. So trying to respond back to it is a pointless, and potentially dangerous game to play. Also, treading into that kind of attack is what will soon be starting wars between nations/military alliances.
Best to suck up any damages/losses and improve your entity's security posture/execution. Hell, you can even buy commercial insurance (YUCK) if you need a control for this. Cost of doing biz nowadays.
Just ranblins from a 27 yr IT/Infosec guy....