A number of North Korean hacking groups were found to have made hacking attempts targeted at a head of a defectors' group in South Korea, according to a report by a U.S. cybersecurity company Thursday.

Pyongyang's hacking groups, including APT37, APT43 and hybrid clusters under the Reconnaissance General Bureau, have targeted Lee Min-bok, head of a defectors' group that sends propaganda leaflets to the North, Mandiant, Google's cybersecurity unit, said in the report.

Mandiant said Lee was a researcher and professor at the Korea Computer Center, a North Korean state-run technology research and development organization, but Lee told Yonhap News Agency that he was actually a researcher at the North's agricultural science institute.

Lee also said he defected from North Korea in 1990 and Pyongyang makes hacking attempts through emails about once a week.

Mandiant said North Korea's hacking operations continue to evolve, in particular in espionage and financial crimes, and its cyber landscape has been streamlined to strengthen cooperation between different hacking groups and develop malware tailored to different platforms, including Linux and macOS. (Yonhap)