SEOUL, March 4 (Yonhap) -- The Web sites of South Korea's presidential office and other major institutions came under a cyber attack on Friday, but there were no immediate reports of damage, industry sources said.
The presidential office Cheong Wa Dae, the Ministry of Foreign Affairs and Trade and top lender Kookmin Bank were among some 40 institutions whose Web sites were infected by the so-called distributed denial-of-service (DDoS) from 10 a.m., AhnLab Inc. said in a statement.
Additional attacks were expected to begin at 6:30 p.m., said AhnLab, South Korea's top information security company.
The cyber attack could disable access to servers and harm PC's hard drives. No immediate damage was reported from the morning attack.
"There was a DDoS attack, but no damage was done," said a Cheong Wa Dae official.
The latest DDoS attack, which was launched by malicious codes that turn personal computers into zombie PCs, bears resemblance to the cyber attack that targeted 17 local Web sites in July 2009, AhnLab added.
Attackers hacked two domestic peer-to-peer file sharing Web sites on Thursday evening and planted malicious codes in files, according to the security company.
South Korea raised a cyber alert level following the attack. The country's telecommunications regulator Korea Communications Commission issued an alert.
The latest DDoS attack also targeted the Web sites of the unification ministry, the defense ministry, the National Assembly, the military headquarters, the U.S. Forces in Korea, the nation's top five lenders, securities companies, major Internet portals and others.