On May 12, 2017, a global ransomware attack occurred against Windows computers which started in Europe and quickly spread around the world. It did not appear to target specific systems or industries. It did cause serious disruption, with United Kingdom NHS hospitals and Spanish telecomm services among the hardest hit. It is also known to have impacted industrial operators running Windows based control systems. The threat to Industrial Control Systems (ICS) from such attacks is particularly pointed: Ransomware on ICS networks causes loss of view and loss of control of industrial processes operating in real time.