For the third day in a row a number of major public and private Web sites in South Korea have been taken off the Internet by a distributed denial of service attack.
The attack hit the Chosun Ilbo daily newspaper, ranked the top news Web site in the country; Internet Auction, one of the largest online auction services; Kookmin Bank; the South Korean President's home page, and the home page of U.S. Forces Korea.
Some sites that were hit a day earlier, including the National Assembly and Ministry of Foreign Affairs and Trade, appeared to be operating normally.
The third wave of attacks began at around 6 p.m. local time (9 a.m. GMT), just as, earlier in the day, computer security specialist AhnLab had warned they would.
This kind of denial of service attack involves sending a massive volume of traffic to a Web site so that it becomes overloaded. While some users will occasionally be able to access the site being attacked, most will see nothing until a network time-out message appears. The type of DOS attack being used against the Korean sites is a distributed DOS attack (DDOS) that sends traffic from a number of different computers to result in an even greater volume of access requests.
The attacks have been headline news in Korean newspapers and on TV news bulletins throughout the day and users are being urged to update their antivirus software or download software from security company home pages.