In its latest 2012 Malnet Report, Breaking the Vicious Cycle of the Malnet Threat and Botnet Infections, it tracked the evolution of malnets, finding more than 1500 unique malnets (malware networks).

In six months, the number of malnets tripled -- from 500 in January 2012 to 1500 in June. Blue Coat estimates that malnets will be responsible for over two-thirds of all Web-based attacks in 2012.

Blue Coat Systems senior malware researcher, Tim van der Horst, said it is a worrying trend because the infrastructures are designed to launch hundreds of simultaneous attacks on unsuspecting users.

"Combatting this malnet threat requires a defence capable of identifying malnet structures and blocking attacks before they can infect the system. Without the right defence in place, users can get pulled into a vicious cycle that perpetuates malnets and spreads infected systems," he said.

Other findings from the study include: