SEOUL -- The South Korean government on Wednesday made a formal confirmation that the Democratic People's Republic of Korea (DPRK) was behind the March 20 cyber attack that paralyzed computer networks at banks and broadcasters.

"The series of cyber attacks last month resembled North Korea (DPRK)'s past hacking patterns," the Ministry of Science, ICT &Future Planning said at a press briefing. "Evidences were secured more or less that North Korea's reconnaissance general bureau did the act."

On March 20, computer networks at three banks and three broadcasters suffered the cyber attack, crippling about 48,700 PCs and servers.

On March 25, there was an attempt to hack PCs of the ordinary people, while computer files at the broadcaster YTN's 58 PCs were destroyed and data at the anti-DPRK organizations' homepage were deleted the following day.

Based on 76 malicious codes used for the hacking and Internet access records collected, the March cyber attack was planned at least eight months ago by indirectly planting malware in advance, according to the probe results by the government-led investigation team.

The investigation team found that six PCs in the DPRK directly or indirectly accessed the infected computers some 1,590 times, among which Internet Protocol (IP) address linked directly to the DPRK was spotted 13 times.