On a sweltering summer day in San Jose, Calif., Scott Noteboom launched a cyberattack by exploiting a networking system vulnerability: the cooling system.

An assistant, standing before a collection of networked computer gear plus a cooling fan, plugged a cable into a laptop. Soon a light on one of the boxes started flashing: The fan was in trouble. It clicked, then stuttered, then moaned to a halt. The equipment soon would have melted down—literally—had the attack occurred in a real data center.

Mr....