There is no escaping the suspicion that spammers have been charting a cagier course in recent months. Electronic messaging managed service provider MessageLabs has noticed too. Previously pristine inboxes are finding that image files and PDFs containing pump-and-dump stock pitches and advertisements increasingly slip through. Excel and Rich Text Format (RTF) spam have also been detected in the wild.

The cause can be summed up by one word: botnets. Although spam has decreased from its peak in July 2004 when it accounted for a staggering 94.5 percent of the email monitored by MessageLabs — it now hovers around 71 percent — the monetary spoils have prompted spammers to pursue more exotic methods of keeping those coffers full. Responsible for spewing spam and dropping the DDoS hammer on Web sites, botnets can hardly be considered an up-and-coming threat. However, a relatively new breed of botnet, spawned by the Storm worm, is proving to be tenacious adversary. Storm Worm Rewrote the Botnet and Spam Game

Technorati Tags: Botnet, Storm Worm