Update from Malwarebytes:
A new strain of ransomware, a Petya-esque variant being called Petya/NotPetya, is swiftly spreading across the globe today, impacting tens of thousands of computers as of 2:00 p.m., PST. More powerful, professional, and dangerous than last month's WanaCrypt0r attack, the Petya-esque ransomware uses the same EternalBlue exploit to target vulnerabilities in Microsoft's operating system. However, unlike WanaCrypt0r, this ransomware instructs you to reboot your computer and then locks up your entire system. Long story short: if you get this infection, you're hosed
From what I have read, if you have kept up your MS updates current you are not at risk. In a network environment, it only takes one computer that hasn't been updated to put your whole network at risk.