"The group, known as Star Blizzard to cyberespionage experts, targeted its victims with emails that appeared to come from a trusted source " a tactic known as spear phishing. In fact, the emails sought access to the victims' internal systems, as a way to steal information and disrupt their activities.

Star Blizzard's actions were persistent and sophisticated, according to Microsoft, and the group often did detailed research on its targets before launching an attack.

Star Blizzard also went after civil society groups, U.S. companies, American military contractors and the Department of Energy, which oversees many nuclear programs, the company said.

On Thursday, a U.S. court unsealed documents authorizing Microsoft and the Department of Justice to seize more than 100 website domain names associated with Star Blizzard.

That action came after a lawsuit was filed against the network by Microsoft and the NGO-Information Sharing and Analysis Center, a nonprofit tech organization that investigated Star Blizzard."

'
"The Russian government ran this scheme to steal Americans' sensitive information, using seemingly legitimate email accounts to trick victims into revealing account credentials," Deputy Attorney General Lisa Monaco said in announcing the U.S. actions against Star Blizzard.

"With the continued support of our private sector partners, we will be relentless in exposing Russian actors and cybercriminals and depriving them of the tools of their illicit trade."