Technical support responded to the Pivnichna substation and took the automated circuit breakers off computer control, restoring power a little after 1 a.m. It was only the second confirmed case of a computer hack triggering an electrical blackout, and compared to the first, 12 months earlier also in Ukraine—it was a buzz, affecting far fewer customers and for a small bit of the time. In the six months since the Kiev attacks, security researchers have wondered why the hackers even bothered with such fleeting disruptions and speculated that someone was using Ukraine as a testing ground for more serious attacks.