The terrifying specter of a future of cyberattacks is that someday, a malicious actor will reach through the internet and cause real, tangible, physical harm. It sounds like a Hollywood plot: a computer is compromised, and suddenly the machinery of a factory is broken. Yet despite the panic, until recently there's only been one such confirmed case. That was Stuxnet, an American-made virus which disrupted an Iranian centrifuge used to enrich uranium in the late 2000s. Then, last month, Germany published a report of another cyberattack turned physical: a furnace at a steel mill that wouldn't shut down.