Users are being warned the Conficker worm is ready for action on the 1 April - although no one is certain what the worm will do.

Conficker is a computer worm that can infect PCs and spread itself across a network automatically, without human interaction.

Chris Thomas, principal consultant for CA's Internet Security Business Unit told CRN, 1 April is when machines infected with the Conficker.C malware will "wake up" and start communicating with each other, waiting for commands.

"The sheer scale of infections is bigger than anything that CA has seen to date," he said.

"Upon activation this multi-million node botnet could be used for anything from sending enormous amounts of SPAM messages and phishing attempts to a large platform from which to launch denial-of-service attacks, disrupting the internet as a whole."

Thomas said as a matter of course, CA is urging PC users to make sure their anti-malware software is up to date with the latest signature.

In February, Microsoft partnered with technology industry leaders and academia to implement a coordinated, global response to the Conficker (aka Downadup) worm.

Microsoft also announced a US$250,000 reward for information that results in the arrest and conviction of those responsible for illegally launching the Conficker malicious code on the Internet.

Along with Microsoft, organisations involved in this collaborative effort include ICANN, NeuStar, VeriSign, CNNIC, Afilias, Public Internet Registry, Global Domains International Inc, M1D Global, AOL, Symantec, F-Secure, ISC, researchers from Georgia Tech, the Shadowserver Foundation, Arbor Networks and Support Intelligence.