South Korea's National Intelligence Service (NIS) today blamed North Korea for hacking into the Seoul Metro subway breaking into and infecting 210 employee computers between March and August in 2014.

The NIS said the hackers implanted 58 malicious codes into the computers using the Advanced Persistent Threat (APT), which is the same methodology that the North Koreans used in 2013 to attack banks and broadcasters in South Korea, according to the Korea Herald.

Seoul Metro said the computers impacted were used for human resources and administrative purposes and that the subway system was never in any danger.

The Korea Herald said Seoul Metro has been a focal point for hackers enduring 350,000 so far this year.