North Korea cyber attack
Investigators check the Korean Broadcasting System's hardware hit by hackers at the Evidence Acquisition Lab of the Cyber Terror Response Centre of the National Police Agency in Seoul. - Reuters

North Korea is planning to launch a massive cyber attack against its southern adversaries alongside a much-feared missile launch, according to reports from Seoul.

The Reconnaissance General Bureau in Pyongyang, which employs thousands of skilled hackers, is said to have been preparing for cyber warfare against South Korea over recent weeks.

According to South Korean daily the Korean Herald, some of the defectors from North Korea have compared the bureau's capabilities with those of Washington's Central Intelligence Agency (CIA).

The spy and special operations bureau was established in 2009 and has been constantly recruiting hacking experts to take down enemy systems, especially targeting Seoul. North Korea is believed to employ at least 12,000 cyber warfare experts across its departments and the number of recruits is increasing every year.

Apart from the designated bureau, Pyongyang operates several other departments which are capable of launching cyber attacks, according to South Korean authorities.

Seoul has blamed Pyongyang for the latest round of cyber attacks, which crippled the networks of South Korea's major broadcaster and a number of banks.

According to the investigation, the attack had been planned since last June and the six PCs involved accessed servers in the South over 1,500 times, using IP addresses in other countries to hide the origin of the attack.

The investigators were able to identify 18 distinct pieces of malware (out of a total of 76) which were used in the attack that had been used in previous cyber-attacks by North Korea.

"An analysis of cyber terror access logs, malicious code and North Korean intelligence showed that the attack methods were similar to those used by the North's Reconnaissance General Bureau, which has led hacking attacks against South Korea," Lee Seung-won, an official at the Ministry of Science, ICT & Future Planning, said in a press conference according to the South Korean Yonhap News Agency.

Cyber experts from Seoul have also reiterated their suspicions after an unidentified North Korean hacker mistakenly accessed networks in South Korea through internet protocol (IP).

READ: North Korea Blamed for March Cyber Attacks on South