Washington (CNN) The Justice Department announced Wednesday that it had seized an internet domain that's at the center of a Kremlin-backed hacking campaign, largely thwarting the potential weaponization of a network of more than half a million web-connected devices across the globe, experts say.

The network of infected devices, or botnet, was one of the largest of its kind, cybersecurity experts say, and capable of intelligence gathering as well as disruptive denial-of-service attacks, which could have cut off internet access to hundreds of thousands of people. Its "VPNFilter" malware had been detected in devices in 54 countries but was "actively infecting Ukrainian hosts at an alarming rate," according to Cisco's cyberintelligence unit, Talos.

The botnet is said in government court filings to be under the control of the Russian hackers known as the Sofacy Group. Private cybersecurity firms have said the group, also known as Fancy Bear, was behind the 2016 hack of the Democratic National Committee and likely affiliated with the GRU, the Russian military intelligence unit.

The move by the Justice Department this week to take over the website that underpins the botnet's "command-and-control infrastructure" is "a critical step in minimizing the impact of the malware attack," the head of the FBI's cyber division, Scott Smith, said in a statement.

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