Original URL: http://www.theregister.co.uk/2008/08/11/s40_security_issues/

'I've cracked Nokia S40 security', claims researcher

Gimme €20k and I'll show you how

By Bill Ray

Posted in Mobile, 11th August 2008 14:35 GMT

Updated A lone researcher claims to have discovered a raft of security issues with Nokia's mid-range handsets, allowing him to remotely install malicious applications with unprecedented capabilities - but he's asking for €20,000 for the details.

The issues are apparently with Nokia's Series 40 platform - the proprietary OS and application stack used on the majority of the company's mid-range handsets. They allow an attacker to install Java applications onto a handset remotely before permitting those applications access to phone functions that should be secured by the Java sandbox.

The flaws were discovered by Adam Gowdiak, whose website provides very few details. But El Reg was able to establish that the initial installation is performed using a silent WAP-Push command, one that bypasses the usual user interaction, in a process that also executes the newly-downloaded application.

Additionally, Gowdiak has discovered a way to convince the Java Virtual Machine that his applications are authorised to access every API on the handset, not to mention native Series 40 functions.

Most Java applications running on a phone are limited in what they can do without the user being warned; particularly when it comes to performing chargeable actions such as making a call or establishing a data connection. But an application signed by the network operator is allowed to do such things, as the network operator is responsible for the billing; similarly, one signed by the device manufacturer can access secure memory and suchlike. Gowdiak's hack provides full access rights to his applications, enabling them to do anything.

Gowdiak believes the hack may be applicable to other handsets using Sun's Java reference implementation, though it's hard to know how widespread the problem is: device manufacturers generally tweak the implementation so some might have inadvertently closed the security hole.

But even if this is limited to Nokia's Series 40 handsets, the numbers are bewildering - we're talking hundreds of millions of devices, and given that a malicious application can be installed with only the target's phone number, the risk is enormous. A hacker might infect a few million handsets within hours, then use them to rig a phone poll and bet on the result, or simply have them all send texts to a premium-rate number - though the latter would be easier to trace.

Given the seriousness of the claims you would have thought Nokia would be leaping on the problem, though the company hasn't responded to our request for comment. Gowdiak tells us he's spoken to both Nokia and Sun, and so far neither company seems interested in stumping up €20K for the details.

The problem here is that Gowdiak's claims are remarkable - for two such serious flaws to be simultaneously uncovered by the same researcher is a tribute to his ability - but remarkable claims require remarkable evidence and Adam can't supply that without the risk of giving away the fruits of his work. He too has a mortgage to pay.

So for the moment there's no advice for Series 40 handset users, except to hope that if the flaws are as easy to exploit as Gowdiak claims, then he's still the only person who knows about them. ®

Update: Adam has sent us a correction stating that his installation mechanism is not WAP-Push based, though he's declined to provide the details of how it does operate, making the flaw even more remarkable as it now involves a new application distribution mechanism too.