The web sites of South Korea's key government agencies and financial institutions came under cyber attack for a second day Saturday, suffering minor damage, communications authorities said.

The Korea and Communications Commission (KCC) said the "distributed denial-of-service (DDoS)" attacks resumed Saturday morning against 29 websites including those of government agencies, Internet portals and banks.

"The homepage of parliament momentarily underwent delays but currently all the websites are operating normally," a KCC official told AFP.

The attacks were fended off as antivirus software was downloaded as a precaution and most "zombie computers" that were inadvertently used to carry out such attacks were turned off on Saturday.

The government and local antivirus firms, however, maintained an alert status for further attacks.

South Korean police have isolated 30 overseas servers that were ordering more than 34,000 zombie computers to carry out DDoS attacks, Yonhap news agency said.

These servers have been traced to 18 countries and territories around the world, including the United States, Russia, Italy, Mexico, Israel and Hong Kong.

Police have contacted overseas law enforcement agencies in attempts to trace the origin of the attacks.

Seoul on Friday issued a cyber security alert as the 29 websites came under DDos attacks.

They included those of the presidential Blue House, the US forces, the military Joint Chiefs of Staff, the ministries of foreign affairs, defence and unification, which handles relations with North Korea, parliament and the tax office.

A DDoS attack often uses viruses planted in "zombie" computers. These seek simultaneous access to selected sites and swamp them with traffic.

In July 2009 a major cyber-attack temporarily shut down 25 sites domestically and in the United States, including those of the State Department, the White House and the Pentagon.

South Korea's spy chief reportedly blamed North Korea's telecommunications ministry for that incident, although US officials reached no conclusion.

In July last year, on the anniversary of the first incident, a number of websites suffered similar DDoS attacks because some contaminated PCs had not been fixed.

earlier related report
South Korea escapes major cyberattack
Seoul (UPI) Mar 4, 2011 - South Korea's government reports little damage or disruption to its computers after a series of cyberattacks.

Nearly 30 institutions and organizations were affected by distributed denial-of-service attacks that overload a site with data causing the site to break down or stop functioning.

The attackers reportedly injected malware into two peer-to-peer file-sharing Web sites, the National Police Agency said.

Government ministries -- including defense and unification -- the National Assembly, a military headquarters, sites for U.S. armed forces in South Korea and major banks were among those hit, an official from the president's office said.

The two biggest Internet portals of Naver and Daum, as well as major commercial banks such as Kookmin, Woori and Shinhan were targeted.

"There was a DDoS attack but no damage was done," the official said.

South Korea's financial regulator the Financial Services Commission and an online stock trading system were shut down but for only a few minutes.

AhnLab, a major security solution provider founded in South Korea in 1995, said it expects more attacks in the next several days. AhnLab said up to 11,000 personal computers were infected by the malware.

"For the PC to not be infected by the malicious code, one must have the latest security patch for the computer operating system and must update the vaccine program, along with checking the system in real time," Kim Hong-sun, chief executive of AhnLab, said.

The attacks are similar to those that targeted South Korean Web sites in July 2009 which were believed to have come from North Korea but never confirmed.

Right after the latest attack, South Korea's state Communications Commission issued an alert for computer users.

"The number of zombie PCs, which are infected by malware and taking part in the attack, currently totals up to 11,000, much smaller than the 115,000 counted during the 2009 cyber attack," a KCC official said. "However, we're aware and making preparation measures since the number is likely to increase."

In April, North Korea, often suspected of being the originating country for cyberattacks, reportedly developed an operating system called Red Star to monitor user activity, even though the use of personal computers by the public isn't as widespread as in South Korea, South Korea's Science and Technology Policy Institute said.

"Due to few applicable programs available, Red Star will not even be easily distributed in North Korea," the STPI said. The Linux-based Red Star operating system uses a popular Korean folk song as its startup music.

In July 2009, the South Korean Defense Ministry announced it would spend more than $20 million to improve security for its computer systems after that month's cyberattacks.

The Cyber Terror Response Center, part of the National Police Agency, set up a team to investigate the cyberattacks. Other departments, including the military, also launched investigations.