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 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.
Distributed denial of service, or DDoS, involves delivering a heavy stream of information and internet traffic, usually with the help of a network of hacked computers, to overwhelm the systems of a target.