This is very troubling news, as a gigantic Denial of Service attack briefly disabled three of the internet’s 13 “root” servers earlier today, including one that handles the Defense Department network: Hackers attack key Net traffic computers.

WASHINGTON - Hackers briefly overwhelmed at least three of the 13 computers that help manage global computer traffic Tuesday in one of the most significant attacks against the Internet since 2002.

Experts said the unusually powerful attacks lasted as long as 12 hours but passed largely unnoticed by most computer users, a testament to the resiliency of the Internet. Behind the scenes, computer scientists worldwide raced to cope with enormous volumes of data that threatened to saturate some of the Internet’s most vital pipelines.

The motive for the attacks was unclear, said Duane Wessels, a researcher at the Cooperative Association for Internet Data Analysis at the San Diego Supercomputing Center. “Maybe to show off or just be disruptive; it doesn’t seem to be extortion or anything like that,” Wessels said.

Other experts said the hackers appeared to disguise their origin, but vast amounts of rogue data in the attacks were traced to South Korea.

The attacks appeared to target UltraDNS, the company that operates servers managing traffic for Web sites ending in “org” and some other suffixes, experts said. Officials with NeuStar Inc., which owns UltraDNS, confirmed only that it had observed an unusual increase in traffic.

Among the targeted “root” servers that manage global Internet traffic were ones operated by the Defense Department and the Internet’s primary oversight body.

UPDATE at 2/6/07 5:48:12 pm:

Here are graphs of the traffic patterns associated with the attacks. Notice that they come in two distinct waves five hours apart: RIPE NCC DNS Monitoring Services. (Hat tip: HHH.)