A top cybersecurity journalist tells the story behind the virus that sabotaged Iran’s nuclear efforts and shows how its existence has ushered in a new age of warfare—one in which a digital attack can have the same destructive capability as a megaton bomb. The virus now known as Stuxnet was unlike any other piece of malware built before: Rather than simply hijacking targeted computers or stealing information from them, it proved that a piece of code could escape the digital realm and wreak actual, physical destruction—in this case, on an Iranian nuclear facility.