Trojans were the most prevalent type of malware worldwide during the last half of 2008 and remained at the top of the list during the first half of 2009, the report states. Worms now are the second most prevalent type of malware worldwide, up from formerly holding the fifth spot during the last half of 2008.
The jump from fifth to second is due in large part to the widespread worm families Conficker and Taterf, the report states. The now-notorious Conficker worm was the most prevalent individual threat family overall, detected by Microsoft on 5.2 million computers during the first half of 2009. Conficker, which includes several variants that spread via removable devices, was also the top threat detected in enterprise environments, according to the report.
“Computers in enterprise environments were much more likely to encounter worms during [the first half of 2009] than home computers,” the report states.
That is because worms often spread through removable storage devices and unsecured file shares, which are widespread in organizations, the report added.
Taterf, a worm that tries to steal online gaming credentials, was the second most prevalent threat family, detected by Microsoft on 4.9 million computers worldwide during the first half of 2009, the report states.
“The worm family Taterf is an interesting case,” the report states. “It targets massively multiplayer online role playing games, which are not common in the workplace, but the techniques it employs (such as infecting removable drives) make it spread more effectively in enterprise environments.”
In addition, rogue security software is still a significant threat, through it was down somewhat this year. Microsoft removed phony AV programs from 13.4 million computers in the first half of 2009, compared to 16.8 million in the second half of 2008, according to the report.