A variant of the Trojan horse attacks known as Storm Worm emerged Monday, <A HREF="http://news.zdnet.com/2100-1009_22-6162623.html?tag=nl.r23660">targeting people who post blogs and notices to bulletin boards.</A>

Storm Worm emerged in January and raged across the globe in the form of e-mails with attachments that, when opened, loaded malicious software onto victims' PCs, commandeering the machines so they could be used for further attacks.

The new Storm Worm variant attacks the machines of unsuspecting users when they open an email attachment, click on a malicious e-mail link or visit a malicious site, said Dmitri Alperovitch, principal research scientist at Secure Computing.