Hackers and other nefarious types have always gone after systems that attract the most users (i.e. Windows for PCs). With the huge increase in the number of users that have smartphones around the world, mobile threats are becoming increasingly common.

Reuters reports that last year the number of threats aimed at mobile phones grew significantly. Security firm McAfee said that the number of new malware threats for mobile devices in 2010 that were discovered rose 46% over the levels in 2009.

McAfee said in a statement, "As more users access the Internet from an ever-expanding pool of devices -- computer, tablet, smartphone or Internet TV -- web-based threats will continue to grow in size and sophistication."

One of the major reasons for the new wave of malware according to McAfee is the wide use of Adobe PDF software and Flash being prime targets of criminals. PDF documents are a major way that malware is spread according to McAfee.

Google Android is being targeted by malware that embeds itself into apps and games according to McAfee. Late last year, a Trojan was let loose in China aimed at Android devices that was creating a botnet.

While malware and Trojans are increasing, McAfee confirms what other security firms have been saying, spam overall is decreasing. The decrease was especially notable in the second half of Q4 2010 when the level of spam dropped 62% by the end of the year compared to the start of 2010. The big drop was linked to botnets that were dormant during traditionally busy time of year.

McAfee itself is undergoing some big changes. Intel is purchasing McAfee, and the acquisition has been given the green light by the FTC and European regulators. The purchase is expected to bring better security to devices with tighter integration into the CPU.