"The reason this wave has attracted our attention is that it is very similar to the Storm worm attacks were seeing last year," said Bureau in an e-mail.

Although Storm used a wide variety of stratagems during 2007 and early 2008, a year ago it rode on the back of a spam campaign based on . Just before those messages flooded inboxes, Storm's creators had tried to tempt computer users into clicking on links promoting .

"[But] this is not the resurrection of the Storm botnet," Bureau cautioned. "Analysis of the binary proves it to be different. It was programmed using a different programming language and includes different functionalities."

Although researchers said that their company's Malicious Software Removal Tool (MSRT) had beaten Storm into submission earlier this year, .

"What we are observing today is proof that malware authors are learning from each other's errors and successes," said Bureau. "After seeing that Storm was able to infect thousands of systems last year with Christmas-related social engineering, the criminals behind other malware families are now trying to emulate that success."