Mobile threats are a growing trend, increasing 93 percent in 2011 over the previous year, according to John Harrison, Symantec group product manager for endpoint threat protection and security technology and response.

"Malware authors are continuing to find ways to monetize a lot of these threats," he told PC World.

While mobile threats are small compared to desktop and laptop threats, he observed, "it's a growing upward trend that we will continue to watch."

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