SEOUL, South Korea -- South Korea said multiple government and private sector websites were hacked on Tuesday's anniversary of the start of the Korean War, and Seoul issued a cyberattack alert warning officials and citizens to take security measures.
Government websites, including the one for the presidential Blue House, and some media sites were attacked, according to a statement from the science ministry. The statement said the sites were hacked and that a team was investigating.
The government alert is meant to warn officials and citizens of possible cyberattacks and urge them to enhance their server and computer security measures.
The shutdown happened on the 63rd anniversary of the beginning of the Korean War. It wasn't immediately clear who was responsible, but both Koreas have traded accusations of cyberattacks in recent years.
South Korean officials say that North Korea orchestrated a cyberattack in March that shut down tens of thousands of computers and servers at South Korean broadcasters and banks. Seoul said in April that an initial investigation pointed to a North Korean military-run spy agency as the culprit.
North Korea in recent weeks has pushed for diplomatic talks with Washington. But tensions ran high on the Korean Peninsula in March and April, with North Korea delivering regular threats over U.N. sanctions and U.S.-South Korean military drills.
Investigators detected similarities between the March cyberattack and past hacking attributed to the North Korean spy agency, including the recycling of 30 previously used malware programs — out of a total of 76 used in the attack, South Korea's internet security agency said.
The March 20 cyberattack struck 48,000 computers and servers, hampering banks for two to five days. Officials have said that no bank records or personal data were compromised. Staffers at TV broadcasters KBS, MBC and YTN were unable to log on to news systems for several days, although programming continued during that period. No government, military or infrastructure targets were affected.
South Korea's National Intelligence Service said North Korea was behind a denial of service attack in 2009 that crippled dozens of websites, including that of the presidential office. Seoul also believes the North was responsible for cyberattacks on servers of Nonghyup bank in 2011 and Joongang Ilbo, a national daily newspaper, in 2012.
North Korea also blamed South Korea and the United States for cyberattacks in March that temporarily disabled Internet access and websites in North Korea, where a small number of people can go online.
Experts believe North Korea trains large teams of cyber warriors and that the South and its allies should be prepared against possible attacks on key infrastructure and military systems. If the inter-Korean conflict were to move into cyberspace, South Korea's deeply wired society would have more to lose than North Korea's, which largely remains offline.