Last Friday, 3/31/2017, we had an issue with a client who was reporting that antivirus had picked up a particular kind of virus, called a worm, which was called Bluber.A. The problem had arisen after a routine software update, so we told the client our tech would roll back that last update and try to figure out where the worm had come from. After that was a success, we pushed the update out again, and the worm did not return. What happened?