Hacker demos Symbian security switch off
Hacker gets straight to the heart
A Spanish hacker has found a way to bypass Symbian's security model, theoretically allowing an unsigned application full access to a S60 phone even on third edition handsets.
F-Secure has identified the application which, once installed on an S60 phone, can selectively switch off security measures which are designed to block malware being able to access critical parts of the phone. In theory this could be combined with a Trojan attack, to make the phone dial a premium-rate number without confirming with the user, for example.
Basic signing systems, such as that used by earlier versions of Symbian and Apple's iPhone, have an all-or-nothing approach – once an application is signed it can do anything, putting the emphasis on testing and placing blame after the event. The latest version of Symbian has a more layered approach - certain actions aren't possible even with a signed application, with different levels of signing allowing different functionality.
This 'onion' approach was intended to address the fact that users will tend to agree to anything, no matter how many times they are warned about possible consequences. It also made signing easier, to the point that even freeware can get signed: signed applications aren't allowed unfettered access, so checking doesn't need to be so vigorous.
The application identified by F-Secure bypasses this layered security, though the user still has to agree to install it programs in the first place. As a side effect the application prevents any other programs being launched - so the user might well notice before any damage is done.
As Steve Litchfield, of AllAboutSymbian, put it to us: "Even if a freebie-seeking user did this... the malware completely breaks the OS and stops other apps running, the user will get VERY suspicious VERY quickly - and power cycle the phone, breaking the hack."
He also pointed out that this issue only exists on older firmware, the latest having been already patched, and added some comments about F-Secure wanting to promote their security package which aren't really repeatable.
The Symbian signing system has stood up remarkably well, though that's got more to do with its intended function than particularly brilliant security. The iPhone stopped people doing what they wanted, so the security crumbled; Symbian generally lets people do what they want, and that's most likely what is keeping it secure. ®