Hier der Newsletter von kapersky.com, dem ich diese Information entnommen habe:

1. Internet Root Servers Attacked
In the latest and particularly dramatic demonstration that no network is safe from the perils of modern computing, Monday evening a sophisticated, large-scale DDOS (distributed denial of service) attack took on the Internet's 13 root servers. Of the 13 root servers, responsible for handling the Internet's DNS (domain name system), only 4 or 5 took the hit (an onslaught of illegitimate service requests) without denying service to legitimate traffic.

As the root server system is designed to maintain normal traffic with just 4 or 5 of the servers functioning, users probably did not notice the attack. Despite this built in service "buffer", a longer and more powerful attack could have slowed traffic down to noticeable levels or even worse.
The FBI among others is investigating the event and at this time no one knows who may be behind this attack. A spokesman for UUNET, operator of two of the 13 root servers said, "This could be someone just messing around, but it could also be something much more serious. It's too soon to say." There is also the danger that this was just a "test" strike, a prelude to a more serious attack in the future.

The majority of DDoS attacks in which the computing power of many computers is focused against an individual or a smaller number of computers, are often perpetrated by hackers who use automated software to scan millions of computers for known security holes. The computers that are found to have the necessary vulnerabilities are usually owned by unsuspecting, innocent home users who are unaware that their computers are taking part in distributed denial of service attacks.

Offering a solution to DDoS attacks Alan Paller, research director at the SANS Institute, a nonprofit security research and training group, warns, "The only way stop such attacks is to fix the vulnerabilities on the machines that ultimately get taken over and used to launch them. There's no defense once the machines are under the attacker's control.