IN THE EVENING of December 23, 2015, the lights went out in parts of Ukraine, plunging more than 225,000 households into darkness. In itself, a blackout in that part of the world might not have attracted much notice. What was unusual: Word came from Kyivoblenergo, a local utility in Ukraine’s Ivano-Frankivsk region, that the outage was due to an illegal entry into its information technology systems. In short, hackers turned out the lights, using their access to the utility’s computer systems to disconnect about 60 substations from the grid.
Source: Harvard Kennedy School – Summer 2016 :: Virtual Arsenal