More than five years after massive cyberattacks left a quarter of a million Ukrainians without electricity, the world’s power grids have become even more vulnerable to hackers.

As utilities turn to sources of renewable energy and add millions of other components like smart meters, they’re rapidly multiplying the number of connections and sensors along their networks, widening the potential for intrusions.

"Power grids are getting increasingly vulnerable because of digitalization and the use of more smart applications,” said Daine Loh, a Singapore-based power and renewables analyst at Fitch Solutions.