SEOUL, June 13 (UPI) -- Hackers of North Korean origin are believed to be behind a large-scale cyberattack against South Korean corporations.
The attack targeted about 10 different company networks, including that of Hanjin Group, the holding group for Korean Air, and SK Group, a leading South Korean conglomerate, local news network YTN reported Monday.
According to police investigations, stolen documents included diagrams for the basic model of the F-15K fighter jet and unmanned aerial vehicles, or drones.
Information on the F-15K's engine and control systems, however, were not leaked because the U.S. manufacturer retains those documents, according to YTN.
The cybercrime investigations unit of South Korea's National Police Agency stated the North has been launching malware attacks against the corporations since July 2014, South Korean newspaper Hankyoreh reported.
"Investigations into a malicious code of North Korean origin that was delivered in February have revealed cyberattacks targeted about 160 separate networks at major companies, public institutions and government agencies, from July 2014 to February 2016," the police statement read.
During the cyberattacks, the South Korean defense ministry's plan to upgrade military communications and private bids for defense projects was also leaked.
Police said the North Korea Internet Protocol address linked to the attacks was identical to a massive data breach in March 2013 against South Korean broadcasters and banks and was traced to Pyongyang, the North Korean capital.
The hackers took advantage of the centralized networks of South Korean corporate and other IT systems in order to find vulnerabilities, according to Yonhap.
The investigations come three months after North Korea attempted to infiltrate South Korea's state rail operator.