A hacking attempt on March 22 targeting the network at the Defense Ministry's press room prompted authorities to block access, the military cyber command said Thursday.
Authorities suspect North Korea was behind the hacking attempt.
The attempt at trying to steal information was traced to the laptop of a journalist, a spokesman said. The laptop had been infected by a malicious code outside the ministry and as soon as it was hooked up to the ministry's network, it apparently attempted to send files stored in the computer to a server IP in Germany.
Military officials here had been monitoring that particular server IP since it was the same that was involved in the massive cyber terror attack against South Korean broadcasters and banks in March last year.
The hacking method this time was the same one the North used to launch massive denial of service attacks in 2011 and a cyber attack on banks and broadcasters last year.
"The computer network at the press room is connected to some of the Defense Ministry's networks, which is linked in turn to the government's network," a cyber command spokesman said. "We can't rule out that a hacker tried not only to steal military information but also launch a cyber attack on Cheong Wa Dae by remotely controlling the laptop."
There have been eight hacking attacks against the Defense Ministry through the computer network since February 2012, the military said. Authorities are considering separating the network at the press room from the military's system.