A Vermont electric utility said it found on one of its laptop computers a malware code the U.S. government says is used by Russian hackers.
The Burlington Electric company said on December 30 that U.S. utilities were alerted by the Department of Homeland Security of a malware code used by Grizzly Steppe, the name given to a Russian campaign to hack U.S. Democratic Party institutions this year.
The company said it found the malware on a laptop that was not connected to its power grid. It said it took "immediate action to isolate the laptop and alert federal officials" and is working with them to prevent other attempts at infiltration.
While hackers apparently did not use the malware to disrupt the utility's operations, U.S. authorities consider any penetration of the nation's electrical system as significant because it represents a potentially serious vulnerability for citizens and the economy.
Officials said the hackers in Vermont may have been testing whether they could penetrate a portion of the U.S. electrical grid.
Russia was blamed for a hack of Ukraine's power grid a year ago that knocked out electricity for about 250,000 people, in the first successful cyberattack on a nation's grid.
Russia has denied the hacking allegations.