Thousands of Apps Secretly Run Ads That Users Can't See

There may be much more advertising in apps than it seems. Thousands of mobile applications are secretly running ads that can't be seen by users, defrauding marketers and slowing down smartphones, according to a new report by Forensiq, a firm that tracks fraud in online advertising.

Over the course of the 10-day study, one percent of all devices observed in the U.S. ran at least one app committing this kind of fraud; in Europe and Asia, two to three percent of devices encountered fake ads. Forensiq identified over 5,000 apps that display unseen ads on both Apple and Android devices. Advertisers are paying about $850 million for these ads each year, according to the report, and the apps with the highest rate of ad fraud can burn through 2 gigabytes of data per day on a single device.