The military has been placed on alert over an intrusive e-mail virus aimed at hacking the military computer networks, defense ministry officials said Sunday.
Since earlier this month, an e-mail titled "New Year's greeting" has been spread to service members with a file attachment, the officials said. When the file is opened, the virus is spread through computer networks.
Against that backdrop, service members have been directed not to store classified information on computer main drives and USB thumb drives.
"We're investigating if there are any personnel who lost their information due to the virus," an official said, asking to remain anonymous.
Earlier this month, the military decided to ban the use of USB flash drives in an attempt to thwart increasing cyber attacks.
The decision came after a South Korea-U.S. operational plan was accessed by a hacker through a USB thumb drive used by an officer at the Combined Forces Command here.
About 2.8 billion won ($2.5 million) will be spent this year in establishing a new data exchange system to replace USB drives.
The new data transfer server, which will link the defense ministry, the Joint Chiefs of Staff and the headquarters of the Army, Navy and Air Force, allows exchange of data between the Intranet and Internet in a safe manner, the official said.
Currently, data transfer between the Intranet and Internet is blocked for security issues, so military officials here often use USB drives for data exchange.
The Defense Security Command said last year that it faced about 95,000 hacking attacks against military networks a day on average.
In July, the government and industrial computer networks suffered from massive distributed denial of service attacks for several days. North Korean hackers were blamed for the attacks by South Korean and U.S. intelligence sources.
North Korea is known to operate a cyber warfare unit that specializes in hacking into South Korean and U.S. military networks to extract classified information.