"In terms of the scale of the attack, I think it was probably North Korea. But the North was likely not going 100 percent full capacity. I would assume they can do more damage and go for more sensitive targets in South Korea, like jamming computer signals in airports, train stations and nuclear reactors," according to Lee.
"I think they were trying to send a message, 'This is what we can do to you; this is a small sample. So watch out, pay up and beware," he concluded.
Broadcasters KBS, MBC and YTN and three banks -- Shinhan, Nonghyup and Jeju -- as well as two insurance firms reported to local police on March 20 that their computer networks were halted for unknown reasons, said a Science, ICT and Future Planning Ministry official who declined to be named.
An analysis by security firm Kaspersky indicated that the attackers used a "Wiper"-style malware program to wipe data on infected computers. In addition, firm Sophos said that malware dubbed Mal/EncPk-ACE, or simply "DarkSeoul," was used in the attacks.
That official explained that his department had been newly created to take over the functions of the Korea Communications Commission as South Korea's civilian anti-hacking watchdog.
"As of March 29, banks and broadcasters hit by the hacking attack had fully normalized their networks. But the investigation into the attack has not yet been closed and we still don't know who masterminded it," the official said. "We're meeting related government agencies often to come up with stronger measures against cyberwarfare."
The defense ministry's Kwon said that in the future, the post of cyber security secretary will be created at the presidential office of Cheong Wa Dae to try to rapidly and efficiently cope with cyberattacks on key national organizations.
"The new anti-hacking watchdog and cyber security secretary, as well as the South Korean spy agency and cyber police, will work closely together to draw up a crisis management plan to cope with possible cyberterrorism against civilian networks," Kwon said. "The defense ministry, which is designing measures to protect its intranet against North Korean hacking, will help these agencies in their battle against cyberwarfare."