KEY POINTS
  • A denial of service attack, which involves overwhelming computer systems with information in a bid to take them down, successfully interrupted electrical systems in Los Angeles County and Salt Lake County in March, according to the Department of Energy.
  • The incident was a rare example of as against an energy utility, particularly in a high population area.
  • Denial of service attacks are relatively rudimentary, and unlikely to be the work of a nation-state, one expert told CNBC.

Electrical grid operations in two huge U.S. population areas — Los Angeles County in California, and Salt Lake County in Utah — were interrupted by a distributed-denial-of-service attack in March, according to the Department of Energy's Electric Emergency and Disturbance Report for March.

The attack did not disrupt electrical delivery or cause any outages, the Department of Energy confirmed, but caused "interruptions" in "electrical system operations." In this case, "operations" does not refer to electrical delivery to consumers, but could cover any computer systems used within the utilities, including those that run office functions or operational software.