Most users set up a password to prevent others from accessing the phone's contents, but a Brazilian man posted a video of himself on the internet showing a quick way of getting around it.
He taps the 'emergency call' button, then enters three # signs, taps the green call button and immediately presses the button on the top of the phone that locks the screen, reports the Guardian.
That simple procedure gives access to the phone app, which contains the address book, voicemail and call history – but it does not allow access to texts, emails or any other iPhone apps.
The iPhone is one of the best-selling handsets on the market, but security researchers have criticised its weak security.
Bug no iOS 4.1 from Salomão Filho on Vimeo.