Malware production was up 22 percent in the first half of 2011 versus 2010, the most ever for this point in a year, and is expected to reach a record for the year, the network security firm McAfee reports in its latest quarterly threat report.

There were about 12 million unique malware samples in the first half of 2011, the busiest first half of a year ever, according to the report, McAfee Threats Report: Second Quarter 2011. McAfee is part of Intel Corp. [INTC].

Moreover, the report shows significant growth for malware on mobile platforms with Android devices becoming the most attacked mobile operating system. Attacks against Android operating system-based devices were up 76 percent, consisting of more than 50 percent of all attacks, McAfee says. Attacks against Android devices were three times that of second place Java micro edition-based devices the report says.

“As we watch steady, significant growth in the mobile malware threat landscape, many of the same functions and features of PC-based threats are already part of the codebase,” the report says. “Mobile threats already take advantage of exploits, employ botnet functionality, and even use rootkit features for stealth and performance.”

A popular way to infect mobile devices is by maliciously modifying apps, basically by corrupting a legitimate app or game that may be downloaded by users, the report says.

In general, attacks are continuing to increase and become more sophisticated.

“This year we’ve seen record-breaking numbers of malware, especially on mobile devices, where the uptick is in direct correlation to popularity,” Vincent Weafer, senior vice president of McAfee Labs, said in a statement. “Overall attacks are becoming more stealth and more sophisticated, suggesting we could see attacks that remain unnoticed for longer periods of time. High-profile hacktivist groups have also changed the landscape by drawing a line between attacks for personal gain and attacks meant to send a message.”

The report says that stealth malware is up 38 percent over 2010.