McAfee’s latest Threat Report has revealed that Android is now the primary target for mobile malware, with nearly all new variants discovered during the third quarter being aimed at the open source operating system.

The McAfee Threats Report: Third Quarter 2011 also revealed that the quarter in question is on course to be the busiest in mobile and general malware history.

McAfee Android Malware Threat
Malware threat by platform

The amount of malware being targeted at the Android system jumped 37% on the previous quarter, McAfee said. In fact, the proliferation of malware this year has meant that McAfee has raised its estimation for the number of unique samples for 2011 from 70 million to 75 million. This would make it the busiest year in malware history, McAfee said.

The report says that while Symbian is still the platform with the "all-time greatest number of malware", Android is "clearly today’s target".

Google has claimed that there are around 500,000 Android activations every single day, so it is no surprise to see malware writers going after the platform. McAfee has highlighted two ways in which Android is primarily being targeted.

McAfee Android Mobile Threat
Malware targeting Android

The first, according to McAfee, is SMS-sending Trojans that gather personal information and use that to steal money from the user. Another is malware that can record telephone conversations and forward it to the cyber-crook, who can then use the information for a variety of nefarious means.

However, not everyone is convinced about the imminent threat to the Android operating system. Chris DiBona, open source program manager for Google, took to his Google+ page to slam reports of threats to Android.

"No major cell phone has a ‘virus’ problem in the traditional sense that Windows and some Mac machines have seen," he wrote. "There have been some little things, but they haven’t gotten very far due to the user sandboxing models and the nature of the underlying kernels."

"Yes, virus companies are playing on your fears to try to sell you bs protection software for Android, RIM and IOS," his rant continued. "They are charlatans and scammers. IF you work for a company selling virus protection for android, rim or IOS you should be ashamed of yourself."

Away from mobile threats, McAfee says that fake antivirus, AutoRun and password-stealing Trojans have regained some of the strength they had lost in previous quarters.

There was also bad news for Apple fans. While many users will claim iOS is inherently more secure than other platforms, McAfee’s report says that malware targeted at Apple’s Mac platform has continued to increase, following what it calls a sharp rise in Q2. McAfee also warned that as the platform continues to grow in popularity, more malware authors will undoubtedly turn their attention to attacking it.