McAfee’s latest Threat Report has revealed Q1 of 2011 to have been the most active first quarter in malware history, with six million unique samples of malware recorded.

Nearly half of the new malware samples picked up during the quarter were recorded in February, McAfee said.

One trend highlighted by the security firm was the emergence of malware aimed at Android devices. The Google-backed open source OS solidified its position as the second most popular mobile platform around, behind Symbian, during the quarter. This trend would not have gone unnoticed by cyber criminals, who have started attacked the platform.

McAfee claims that Android’s ability to "sideload" (adding an app or data to a mobile device from a PC rather than via a wireless network) coupled with the fact that users are not restricted to getting apps from a centralised app store and that there is no centralised place where Google can check apps for suspicious behaviour have raised the security risks for Android users.

It was all bad though, according to McAfee. Thanks to the takedown of a number of botnets, most notably Rustock and Zeus, spam levels to drop all over the world. Spam emails now total around 3.1 trillion per day, which may sound a lot but is less than half what it was a year ago. Spam emails now outnumber genuine emails by a ratio of 3:1.

However the spam battle is not yet won and others, including Maazben, Bobax, Lethic, Cutwail and Grum are stepping up to fill the void left by Rustock and Zeus. McAfee noted a "strong uptick" in new botnet infections toward the end of Q1.

"The Q1 Threats Report indicates that it’s been a busy start to 2011 for cybercriminals," said Vincent Weafer, senior vice president of McAfee Labs. "Even though this past quarter once again showed that spam has slowed, it doesn’t mean that cybercriminals aren’t actively pursuing alternate avenues."

"We’re seeing a lot of emerging threats, such as Android malware and new botnets attempting to take over where Rustock left off, that will have a significant impact on the activity we see quarter after quarter," he added.

Recently we have seen an increase in attacks aimed at Apple devices, with two fake antivirus attacks hitting in May, with the aim of luring users into believing they have an infected machine before charging them to "remove" it. Apple responded by updating its software to remove the threat.

Security company F-Secure recently announced the release of antivirus software specifically designed to protect Mac machines.