(CNN) -- Hackers stole data belonging to multiple electric utilities in an October ransomware attack on a US government contractor that handles critical infrastructure projects across the country, according to a memo describing the hack obtained by CNN.CNN) -- Hackers stole data belonging to multiple electric utilities in an October ransomware attack on a US government contractor that handles critical infrastructure projects across the country, according to a memo describing the hack obtained by CNN.
Federal officials have closely monitored the incident for any potential broader impact on the US power sector while private investigators have combed the dark web for the stolen data, according to the memo sent this month to power company executives by the North American grid regulator's cyberthreat sharing center.