By penetrating the networks of downline vendors, Russian hackers gained access to a reportedly secure, isolated network, allowing them to eventually reach the control rooms of US utilities, according to the Wall Street Journal.
The state-sponsored hacking group, which poses a serious threat to critical infrastructure, has been on the watch list of the Department of Homeland Security (DHS) since 2014. Using stolen credentials gained through spear-phishing emails and watering-hole attacks, the hackers's activity long went undetected, which allowed them to steal confidential information and “familiarize themselves with how the facilities were supposed to work,” WSJ reported.

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