North Korean hackers have launched a campaign to distribute a popular software tool that can be used to spy on users and steal information, in the latest Pyongyang attack to use freely available software for espionage.

South Korean cybersecurity firm AhnLabs published the findings in a new report Tuesday, which states that hackers linked to the Pyongyang-backed Kimsuky group began distributing the remote administration tool (RAT) on Jan. 24 via a new variant of the Gold Dragon malware, one of the group’s signature backdoors.

The researchers do not describe the attack vector, but Kimsuky is known for delivering malware-infected Word