From my Forbes blog:

For years, scammers have been hijacking people’s computers into so-called botnets, opening hidden browser windows and automatically clicking on ads. That’s fooling advertisers and their ad agencies into thinking real people saw their ads, costing them billions of dollars a year in wasted spending.

Now, the fraudsters have started moving to mobile phones. Using a technique that one ad fraud detection company calls mobile device hijacking, the scammers use mobile apps such as games that run as many as 20 ads a minute, then simulate random clicks. Forensiq, a New York firm that provides ad fraud detection and prevention, today is releasing one of the first studies to look at the relatively new technique.

Already, the company says, more than 12 million devices have been infected–about 1% of devices Forensiq observed in the U.S. and 2% to 3% in Europe and Asia. Forensiq figures that the hijacking affects some 13% of all in-app advertising impressions.

The cost to advertisers is adding up quickly, Forensiq founder and CEO David Sendroff said in an interview. He projects that in-app ad fraud, which the company estimated at $857 million last year, will pass $1 billion worldwide this year.

Users generally don’t see any of this happening on their phone, at least not directly. But the apps–some 5,000 identified by Forensiq–still can be a plague on their phones. Forensiq found that in as little as an hour, a malicious app can download two gigabytes of images and videos, draining battery life and potentially burning through data limits. …

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