Washington Government and private security officials made a last-ditch effort Tuesday to persuade Internet site operators to inoculate their computers against the predicted return of the viruslike "Code Red" worm.
The worm was expected to become active at 8 p.m. EDT, but there was no sign it had gone to work by late Tuesday night, according to federal officials monitoring Internet traffic.
"There has been an amazing effort to ensure that the public and private sector proofed their computers against (Code Red)," said Ronald L. Dick, the director of the FBI's National Infrastructure Protection Center.
"As of now, the Internet is operating normally."
Officials said, however, it could be a day or two before any effects of the latest attack were noticed, as the worm or possible variants take hold.
The malicious program can only be stopped if enough Web site operators install Microsoft's software patch, which plugs the security hole the worm uses to attack.
FBI officials said late Tuesday that more than a million people had downloaded the patch from Microsoft.
"This should have a measurable impact upon the overall effect of the worm," the FBI's National Infrastructure Protection Center said in a statement.