Two tech boffins have uncovered a dirty little secret lurking deep inside iPhones and iPads - Apple is secretly tracking your movements and storing the data in a simple text file on the devices.
What the researchers can't explain was why Apple was doing it.
Pete Warden and Alasdair Allan said the tracking facility was added in iOS 4 and stored detailed coordinates of locations visited by handset owners, sparking serious privacy concerns.
"Apple has made it possible for almost anybody – a jealous spouse, a private detective – with access to your phone or computer to get detailed information about where you've been," Warden told the Guardian.
The researchers found that a file within iOS contained longitude and latitude coordinates and a time stamp - and that combining these with a simple mapping application would give anyone a detailed breakdown of everywhere a user had been.
The researchers said they had looked for similarly intrusive tracking technology in Android and had not found any evidence, but said they did not believe the data was being beamed back to Apple.
Mobile networks already stored location information, but that was only available to law enforcement officials with a search warrant and was stored in secure data centres and not on vulnerable handsets in plaintext.
According to the researchers, the data would be transferred to new handsets if the consumer upgraded, but the question remained why Apple would even want to store the data.
"Apple might have new features in mind that require a history of your location, but that's our speculation,” the Guardian quoted the researchers as saying.
“The fact that [the file] is transferred across when you migrate is evidence that the data-gathering isn't accidental."
Apple has not yet responded to a request asking why it was collecting the data.