116 of a total of 178 identified mobile threats in 2011 affected Android; 55 targeted Symbian, two programs targeted PocketPC and five were aimed at J2ME.
The number of threats directed at Android in 2011 was a sharp increase from only 9 threats in 2010 -- only trumped by the number of threats for Symbian in 2006 (188) and 2005 (125). Since 2004, F-Secure listed a total of 710 security threats for mobile device. 525 of those affect Symbian, 125 Android, 40 PocketPC, 18 J2ME and 2 iOS. The vast majority of all mobile threats were trojans (519 overall, 136 in 2011). Viruses (56 total) have not been seen since 2007 and worms (38 total) appear to have been abandoned as well.
Minor, but evolving categories of mobile malware include monitoring tools and riskware, both of which saw sharp increase in 2011. Riskware incidents climbed from one incident in 2010 to 10 cases in 2011. F-Secure reported 14 monitoring tool problems in 2011, up from just one in 2010.
In related news, Android is now the most popular mobile browser.