Scammers drained Android phone batteries and made piles of money

A new scam has been discovered that manipulates Android devices to earn ad revenue without the user’s knowledge. The scam, unearthed by fraud detection firm called Protected Media (with additional investigating by BuzzFeed), affected the banner ads in several Android apps.

The scheme involved stacking multiple video ads behind a typical ad banner. These additional ads would register as having been watched — generating ad revenue for the scammers — even though the user wouldn’t see them. A smartphone’s battery would still drain as if the user had been watching numerous video ads.

It’s a type of ad fraud known as Ad Stacking and it can be very lucrative. Protected Media CEO Asaf Greiner said they found a new version of it last Autumn and he’d observed “tens of millions of dollars worth” of these video ads running per month.

As well as the damaging effect these scams have on the advertising industry, this sounds like a nightmare for the people who’s phones have been dying seemingly without reason. We don’t know how many were affected, however.

The scam was traced to an ad technology company called Aniview, and some questions were raised about its involvement. Aniview has denied any wrongdoing and said it was fighting against bad activities and usage of the platform.

Read next: Common phone scams you should be aware of

Regardless, it doesn’t seem like these kinds of scams are gone for good and it’s a difficult one to address given that the process is hidden from view. If you suspect your phone has such a problem, and can narrow it down to a specific app, it might be worth uninstalling it and letting the developer know about the issue.