The movements of iPhones and 3G iPads have been have been recorded by Apple in a hidden file, since the introduction of its iOS 4 operating system, researchers have found.
On Thursday, at the Where 2.0 conference, researchers Alasdair Allan and Pete Warden said geographic information is written to a database that is restored across operating system backups and device migrations and is hidden from the user.
"What makes this issue worse is that the file is unencrypted and unprotected, and it's on any machine you've synched with your iOS device," Allan wrote on Thursday. "It can also be easily accessed on the device itself if it falls into the wrong hands."
"Anybody with access to this file knows where you've been over the last year, since iOS 4 was released," he wrote.
Though the data is stored on local devices and synced devices, there is "no evidence that it's being transmitted beyond your device and any machines you sync it with," the researchers said.
A FAQ page is available along with an open source application that displays the hidden file and outputs the data as a user's location history on a map.
Apple's operating system was renamed to iOS 4 alongside the release of the iPhone 4 in 2010. The 3 and 3GS incarnations of the iPhones can be upgraded to it as well.
At the time of writing, the researchers had not heard back from Apple, which they had contacted for information.