Researchers have discovered hidden files in iOS 4 which allow 3G devices, such as the iPhone 4, to store location data.
The findings, revealed yesterday, indicate this has been going on for almost a year.
Pete Warden made the discovery and investigated with the help of Alasdair Allan of the University of Exeter. It appears the hidden files recorded the latitude and longitude of the phone's recorded coordinates and a timestamp, which could allow a user's movement patterns to be recognised and exploited.
The researchers said the location data is stored on the device itself, but they see no evidence to suggest it is transmitted to Apple, or anywhere else. However, it is unencrypted, meaning there are still security concerns personally sensitive location data could fall into the wrong hands.
What is particularly worrying is automated backups of iPhone data can end up on your computer, including the tracking data, which makes it potentially much more accessible to cyber criminals, as well as anyone who actually steals your handset, tablet, laptop or PC.
The data is also transferred between replacement devices.
The researchers have speculated all this could be a precursor to Apple offering extended location based services, whilst others have suggested location-based advertising as a possibility.
Warden and Allan have subsequently looked at other systems, including Android, to see if this process occurs elsewhere, but said only Apple products recorded locations in this way.
Apple has yet to comment on the issue but Microsoft was quick to state Windows Phone 7 does not store location data.
Many commentators are claiming Apple is doing this without user's permission, but it does appear to be covered by the company's Terms and Conditions (T&Cs), which users agree to before using Apple products. The T&Cs do outline the rights of the company to "collect, use, and share" location data.
Location-Based Services
"Apple and our partners and licensees may collect, use, and share precise location data, including the real-time geographic location of your Apple computer or device. This location data is collected anonymously in a form that does not personally identify you and is used by Apple and our partners and licensees to provide and improve location-based products and services. For example, we may share geographic location with application providers when you opt in to their location services."
Some location-based services offered by Apple, such as the MobileMe "Find My iPhone" feature, require your personal information for the feature to work.
