STUXNET
T hree years after it was discovered, Stuxnet, the first publicly disclosedcyberweapon, continues to baffle military strategists, computer security experts, political decision-makers, and the general public. A comfortable narrative has formed around the weapon: how it attacked the Iranian nuclear facility at Natanz, how it was designed to be undiscoverable, how it escaped from Natanz against its creators’ wishes. Major elements of that story are either incorrect or incomplete. That’s because Stuxnet is not really one weapon, but two. The vast majority of the attention has been paid to Stuxnet’s smaller and simpler attack routine — the one that changes the speeds of the rotors in a centrifuge, which is used to enrich uranium. But the second and “forgotten” routine is about an order of magnitude more complex and stealthy. It qualifies as a nightmare for those who understand industrial control system security. And strangely, this more sophisticated attack came first. The simpler, m