Dyman & Associates Risk Management Projects

Traditional advice is to use the official app stores to avoid mobile malware – but a Spanish security firm has discovered four apps available via Google Play that scam their users into covertly subscribing to premium SMS services and stealing money through their phone bills.

Luis Corrons, technical Director of Panda Security's PandaLabs research arm, blogged about the discovery yesterday. His team had found four particular apps (on dieting, baking, exercise and hairstyling) that all use a similar process to scam their users. The basic methodology is to trick the user into accepting terms and conditions well beyond those expected.

Using the diet app as an example, Corrons shows that users are presented with an invitation to view one of the diets. Clicking 'Enter' pops up a small window that asks the user to accept the app's terms of service – but those terms are separated from the pop-up, greyed out, and in tiny, unreadable text. They actually grant the app permission to subscribe the device to an external service.

Of course, it's not as simple as that. Firstly, the app 'steals' the user's phone number from WhatsApp (a popular app that requires the user's number and is statistically quite likely to be installed). It then covertly subscribes the user to a premium SMS service, waits for the confirmatory request from the service, intercepts it and responds in the affirmative – all without any notification to the user. The user eventually gets presented with a bill 'hidden' in the mobile phone charge for a service he didn't know he was using.

This type of scam is a growing problem. "I know that lots of people only ever give their bill a cursory glance or don’t even bother looking if it stays under a certain amount. I manage all the bills in our house after I discovered my missus had being paying insurance and tech support on a phone she hadn’t used for 5 years," a PandaLabs spokesperson told Infosecurity.

"Whether the