The company has gone to great lengths to secure customer data in recent years, by implementing better encryption for all phones and refusing to undermine that encryption.

But private information still escapes from Apple products under some circumstances. The latest involves the company's online syncing service iCloud.

Russian digital forensics firm Elcomsoft has found that Apple's mobile devices automatically send a user's call history to the company's servers if iCloud is enabled — but the data gets uploaded in many instances without user choice or notification.

"You only need to have iCloud itself enabled" for the data to be sent, said Vladimir Katalov, CEO of Elcomsoft.

The logs surreptitiously uploaded to Apple contain a list of all calls made and received on an iOS device, complete with phone numbers, dates and times, and duration.