Security company ESET has revealed that the cyber-attack on the Ukrainian power grid was broader than initially reported.
Prykarpattyaoblenergo, a western Ukraine power company, reported an outrage on 23rd December, after which all fingers were pointed towards Russia.
The incident, which took place at the Ivano-Frankivsk region of Ukraine, left the town without electricity for several hours in December 2015.
The attackers reportedly used BlackEnergy Trojan malware to carry out the attacks.
Over the past two years, numerous reports have surfaced regarding a Moscow-backed group, dubbed Sandworm, using the Trojan for targeted attacks.
The Trojan was reportedly developed in 2007 to carry out distributed denial of service (DDoS) attacks and has since been upgraded to carry out more sophisticated tasks.
In Ukraine, two other utilities also found similar malware in networks, according to Bratislava-based security company ESET.
According to ESET senior malware researcher Robert Lipovsky, similar malware was found in the networks of at least two other utilities those were ESET customers.
Reuters cited iSIGHT head of cyber espionage intelligence John Hultquist as saying: "There is pretty strong consensus that there was a blackout caused by a computer network attack."