North Korea is suspected of having hacked a personal computer owned by the leader of a North Korean defector group based here, South Korean police said Wednesday.

Chang Se-yool, who leads the group, was the victim of so-called “spear phishing” attacks in April, May and November this year, resulting in a massive leak of private data stored on his computer, the National Police Agency said.

Spear phishing is a virtual trap that targets a specific individual or organization, seeking unauthorized access to their confidential data. Spear phishing attempts are not typically initiated by random hackers but are mostly conducted by criminals.

The NPA officers said that Pyongyang is highly likely to be the perpetrator behind the three attacks, after analyzing the hacking method and Internet protocol addresses used for the attack, which were traced back to China.

“We are weighing the possibility that the perpetrator of this crime could be North Korea, judging from a variety of circumstances,” an NPA official close to the investigation said. “I believe that North Korea sent a warning message to Chang.”

North Korea was previously blamed for a series of cyber attacks on South Korean bank networks as well as hacking into government agency systems, including that of the presidential office Cheong Wa Dae.

According to a report by Seoul’s spy agency, North Korea operates seven hacker organizations, with a total of about 1,700 members.

The North also has spies in China and Japan who distribute pro-Pyongyang propaganda, it said. (Yonhap News)