An Internet worm unleashed on Saturday impaired key systems in the U.S. government and private sector, delaying operations at one major airline and several media organizations, and knocking banks' cash machines offline.
At least 160,000 computers worldwide have been infected since the worm debuted early Saturday morning, said Peter Allor, operations director
of the Information Technology Information Sharing and Analysis Center.
"That's really a conservative estimate," Allor said. "We'll know about the extent of this attack in a few days."
The effects of the worm -- known variously as "Sapphire," "Slammer" and "SQ-Hell" -- have diminished in many parts of the world since Saturday. Major Internet service providers were able to block traffic destined for servers running a vulnerable Microsoft Corp. database program called SQL Server 2000.
The FBI is investigating the attack, a spokesman for the bureau's National Infrastructure Protection Center said.
Bank of America Corp. said Saturday that most of its 13,000 automatic teller machines could not process customer transactions for part of the day because of the bug.
Other banks also struggled this weekend with the effects of the worm, said Suzanne Gorman, chairman of the Financial Services Information Sharing and Analysis Center, which represents some of the nation's largest financial services companies.
"There were a lot of our members affected by this," said Gorman, who declined to give more details.
The worm caused flight delays and cancellations for Houston-based Continental Airlines after it overwhelmed the company's online ticketing systems and electronic kiosks that travelers use to check
in, said company spokesman Jeff Awalt.
Continental brought the ticketing and kiosk stations back online by mid-afternoon Saturday, but the airline's Web site was down for most
of Sunday, causing wait times on its reservations hotline to soar to more than 140 minutes.