About a dozen times in the last decade, sophisticated foreign hackers have gained enough remote access to control the operations networks that keep the lights on, according to top experts who spoke only on condition of anonymity due to the sensitive nature of the subject matter.
The public almost never learns the details about these types of attacks - they're rarer but also more intricate and potentially more dangerous than data theft.
Information about the government's response to these hacks is often protected and sometimes classified; many are never even reported to the government.
How organisations can stop wasting their best ideas
Justin Lowe said: “We've got these vulnerable systems out there that are old and never had security built into them, and now we're exposing them to a wider audience. That wider audience is getting much more hostile.”