The federal government said that early Tuesday it detected a series of electronic attacks against U.S. Internet providers, launched hours after the FBI alerted technology companies and others of potential trouble.
The alert, sent out Monday evening and based on information from Italian authorities, cited "credible but nonspecific information that wide-scale hacker attacks" were planned against U.S. Web sites and Internet providers, "possibly emanating from Western Europe," a U.S. official said, speaking on condition of anonymity.
"There was a real spike in Internet traffic at odd hours," confirmed Richard Clarke, the Bush administration's top official for cyber-security. "It was clearly unusual because it was five times and seven times normal, but it didn't take anything down."
One firm that monitors the health of the Internet, Matrix NetSystems Inc., said it detected a 1 percent decrease in Internet accessibility within hours of the attacks, and a small number of the 3,000 Internet devices it monitors were completely overwhelmed within the United States. Analyst Abelardo Gonzalez said a 1 percent drop was a rare enough event that it probably reflected an impact from the attacks.
But most such organizations and companies said they barely detected a hiccup of unusual activity, with few reports of odd outages or even widespread e-mail delays.