The proportion of infected computers worldwide decreased significantly from 38.49 percent in 2011 to 31.98 percent in 2012, according to Panda. The decrease could be due, in part, to the significant rise in use of smartphones and tablets. Driving much of the malware are nearly 30 automated attack toolkits available to cybercriminals on popular hacking forums. Panda and other security firms say BlackHole has become the most popular exploit toolkit. It is frequently rented out to cybercriminals and receives regular updates with new exploits.