An investigation by the Wall Street Journal has revealed that a large number of smart phone apps share user data without asking permission.
The scary report shows that a number of app developers are bypassing even the strict rules imposed by the likes of Apple, in order to transmit large amounts of personal data to third parties including advertising outfits.
The newspaper tested 101 popular applications using signal-sniffing technology, and found that 56 of them transmitted the handset's unique device identification code to other companies "without users' awareness or consent".
Nearly half of the titles transmitted location data, and five were found to be sending out data on the user's age, gender and postal code.
Messaging app TextPlus 4 seems to be the biggest offender, spewing all of the aforementioned information to eight different advertising companies.
Android and iPhone versions of music player Pandora and popular game Paper Toss also came under fire for sharing data with five ad outfits without asking.
Although Apple insists that iPhone apps "cannot transmit data about a user without obtaining the user's prior permission and providing the user with access to information about how and where the data will be used," the WSJ insists that many of the apps it tested appeared to violate that rule.
Unsurprisingly, world-dominating internet superpower Google was the biggest recipient of dodgy data, with 38 of the 100 apps tested sending info to the company's servers.