Fake security tools still big threat, worms on rise

"All over the world, it has become the No. 1 threat," said Akif.

There were 16.8 million infections in 2008 compared to 13.4 million in the last six months. But rogue security software is morphing, becoming more sophisticated in how it attacks, said Akif. It's more difficult to identify now because they do things like latch on to free software.

While rogue security software is typically not a huge pain for large enterprises with security policies in place, Akif said resource-constrained small to medium businesses are an easy target.

According to Toronto-based security consultant, Brian O'Higgins, rogue security software is particularly crafty because it preys on a combination of fear and training.

"People have been trained to be concerned about security,and when a pop-up comes on that claims your machine is at risk, they are willing to install the software," said O'Higgins.