Go-time for Conficker worm, no problems

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The worm's programming included a change in tactics on April 1: The estimated 3 million to 12 million computers infected by Conficker were told to step up their attempts to "phone home" for commands. But that seemed to be the only sign of life from the bug.

"One thing we're not seeing is any mass malicious activity," said Joris Evers, an analyst with McAfee. "The Internet today is working just as well as it was working yesterday."

The worm can take control of unsuspecting PCs running Microsoft's Windows operating system. But its creators likely want to use their vast "botnet" to send spam or perform other cybercrimes, and not to bring down the Internet.

That's one reason analysts say the people behind the virus will probably wait to send any commands. "Everyone who is fighting Conficker is on high alert," Evers said.

Security companies monitoring the worm have been largely successful at blocking infected machines from communicating with whoever programmed it.

Microsoft issued a software update, called a "patch," to protect PCs from vulnerability back in October. But not everyone applied the patch.

In one telltale sign of an infected machine, Conficker blocks Microsoft's site as well as those of most antivirus companies. Computer owners can work around that obstacle by having someone else e-mail them a Conficker removal tool.

One important note -- Conficker attacks Windows computers, not Macs.