A protective relay attached to that generator was designed to prevent it from connecting to the rest of the power system without first syncing to that exact rhythm: 60 hertz. But Assante’s hacker in Idaho Falls had just reprogrammed that safeguard device, flipping its logic on its head.

At 11:33 am and 23 seconds, the protective relay observed that the generator was perfectly synced. But then its corrupted brain did the opposite of what it was meant to do: It opened a circuit breaker to disconnect the machine.

When the generator was detached from the larger circuit of Idaho National Laboratory’s electrical grid and relieved of the burden of sharing its energy with that vast system, it instantly began to accelerate, spinning faster, like a pack of horses that had been let loose from its carriage. As soon as the protective relay observed that the generator’s rotation had sped up to be fully out of sync with the rest of the grid, its maliciously flipped logic immediately reconnected it to the grid’s machinery.

The moment the diesel generator was again linked to the larger system, it was hit with the wrenching force of every other rotating generator on the grid. All of that equipment pulled the relatively small mass of the diesel generator’s own spinning components back to its original, slower speed to match its neighbors’ frequencies.

On the visitor center’s screens, the assembled audience watched the giant machine shake with sudden, terrible violence, emitting a sound like a deep crack of a whip. The entire process from the moment the malicious code had been triggered to that first shudder had spanned only a fraction of a second. //

The test director ended the experiment and disconnected the ruined generator from the grid one final time, leaving it deathly still. In the forensic analysis that followed, the lab’s researchers would find that the engine shaft had collided with the engine’s internal wall, leaving deep gouges in both and filling the inside of the machine with metal shavings. On the other side of the generator, its wiring and insulation had melted and burned. The machine was totaled.

In the wake of the demonstration, a silence fell over the visitor center. “It was a sober moment,” Assante remembers. The engineers had just proven without a doubt that hackers who attacked an electric utility could go beyond a temporary disruption of the victim’s operations: They could damage its most critical equipment beyond repair. “It was so vivid. You could imagine it happening to a machine in an actual plant, and it would be terrible,” Assante says. “The implication was that with just a few lines of code, you can create conditions that were physically going to be very damaging to the machines we rely on.”

But Assante also remembers feeling something weightier in the moments after the Aurora experiment. It was a sense that, like Robert Oppenheimer watching the first atomic bomb test at another US national lab six decades earlier, he was witnessing the birth of something historic and immensely powerful.

“I had a very real pit in my stomach,” Assante says. “It was like a glimpse of the future.”