Mobile device hijacking, a new type of ad fraud performed by apps that rapidly load hidden ads and emulate human behavior, affects 13 per cent of in-app pre-bid advertising globally.

Thats according to a Forensiq study, which found that more than 12m mobile devices were flagged as being hijacked. Thats bad news for the consumer, as hijacking can waste up to 2GB of mobile data each day.

But its even worse for mobile advertisers, with in-app fraud forecast to exceed $1bn (£650m) in 2015.

“With mobile ad spending expected to overtake desktop spending in 2016, tracking fraudulent behavior and raising awareness to new threats such as mobile device hijacking is essential to building a more sustainable and overall safe advertising ecosystem,” said David Sendroff, founder and CEO of Forensiq. “We hope this study will open a discussion and bring all stakeholders together around the issue.

Want to know more about ad fraud? Check out our recent Big Issue feature for the full low-down on the topic.