A security bug has been detected and its real serious. Visiting a page and trying to read a simple PDF file can turn fatal and give full control of your iPhone or iPad to the hacker.
This security bug affects all iOS4 devices including the iPad.
The vulnerability is easily exploitable. In fact, the latest one-click, no-computer-required jailbreak solution for iOS 4 devices uses this same method to break Apple’s own security. But this is only to help the user.
How it works ?
It just requires the user to visit a Web address using Safari. The website can automatically load a simple PDF document, which contains a font that hides a special program. When your iOS device tries to display the PDF file, that font causes something called stack overflow, a technical condition that allows the secret ninja code inside the font to gain complete control of your device.
The result is that, without any user intervention whatsoever, that program can do whatever it wants inside your iPhone, iPod Touch or iPad. Anything you can imagine: Delete files, transmit files, install programs running on the background that can monitor your actions … anything can be done.
This is not the first time that something similar has happened. At the beginning of the iPhone’s life there was a problem with TIFF files that also caused the same security breach. Apple patched the bug after a while, but back then there were very few iPhones compared to the current installed base. Apple says that there are 100 million iPhones, iPod touches, and iPads in the world. Obviously, malicious hackers are racing to get a slice of that market.
How can you avoid it?
Right now, the easiest way to avoid this problem is by not going to any PDF links directly and not loading any PDF from any non-trusted source.
You can also jailbreak your iPhone and install a program that will ask for authorization every time your browser encounters a PDF (just look for “PDF loading warner” in Cydia).