How much does your phone know about you? And who does it tell?
Earlier this year, the photo sharing company Path apologised and deleted address books it had uploaded from users without their consent. Apps must now ask before accessing this data, just as they do with a device's location.
But privacy experts are drawing attention to analytics firms that monitor when, where and how people are using apps. An RMIT University cyber security expert, Mark Gregory, said a "huge market"had developed in analysing what people were doing on their phones.
One US company, Flurry Analytics, tracks 1.4 billion app sessions a day from more than 600 million smartphones and tablets. It offers more than 70,000 companies the chance to "identify your best segments by demographics, interest, geography, usage and more".
US-based researcher and consultant Ashkan Soltani said people are most valuable to advertisers when they have a baby, a house or a spouse.
He is one of three researchers behind MobileScope, a product designed to monitor everything that flows from mobile devices through apps. It is only available to app developers and researchers but the company hopes to offer it to the wider public soon.