Could hackers turn the lights out?

Just before Christmas, that theoretical threat became all too real for more than 225,000 Ukrainians who were plunged into darkness by a sophisticated attack on one of the nation’s power companies.

The attackers struck late in the afternoon on 23 December and used the remote access they had gained to computers in the control centre of power firm Prykarpattyaoblenergo to flip circuit breakers and shut down substations.

In total, about 30 substations were turned off, including those that served one of the control rooms for Prykarpattyaoblenergo, so staff struggling to get the lights back on were forced to find a fix in the dark.