Threat actors have managed to infect the network of an Indian nuclear power plant with malware, the Nuclear Power Corporation of India Limited (NPCIL) has admitted, adding that India’s national computer emergency response team (CERT-In) discovered the issue last month.

NPCIL stated that an investigation by India’s Department of Atomic Energy “revealed that the infected PC belonged to a user who was connected to the Internet connected network used for administrative purposes,” which “is isolated from the critical internal network.” The malware used in the attack is Dtrack, which shares similarities with malware that has been linked to the North Korean state-sponsored hacking group known as Lazarus.

Read more: Indian nuclear power plant’s network was hacked, officials confirm