County I work for got hit with one of these a couple of years ago. Because of good backup, and a lot of luck (They had backed up the system at noon, and the virus hit at 4:30) the IT people were able to tell the hijackers to kiss off. A couple of hours of work product was lost. Took a week to check and clear every computer on the network. And, my court bought our own backup system so we aren't dependent on the IT people