Apple pulls jailbreak detection API

Knowing the known unknowns

Apple has dropped support for the API that allows applications to ask if an iOS device has been jailbroken, though it seems that not a lot of people trusted it anyway.

The API was only introduced six months ago, but according to Infoworld has now disappeared or been disabled, leaving vendors of security products reliant on their own techniques to find out if a particular iOS device has been hacked open – which, it turns out, they were doing anyway as no one trusted the OS's word on the matter.

Jailbreaking is something owners of iOS devices do if they want to install applications they've developed themselves, applications of which Apple doesn't approve, or pirated applications for which they'd prefer not to pay... The Jailbreaking community is divided roughly along those lines, though many of the latter like to think of themselves as the former. In June, Apple updated the Mobile Devices Management API, which included a simple query allowing an application to ask the OS if it had been jailbroken: the API asked the OS to check various key indicators and report back, allowing the application to take appropriate steps.

That's more important in a corporate setting, where keyboard-sniffing software might be installed on a jailbroken device to intercept passwords or other corporate data. A simple check built into the corporate VPN or email client would render that impossible, assuming the API could be trusted.

Which is rather the problem – once the device is jailbroken, nothing the OS says can be trusted, so secure-client vendors already perform various checks of their own, which vary between vendors and gain some (limited) security through obscurity.

Those secure client vendors will end up racing the hackers, patching their own clients as the hackers create jailbreaks that forge credentials – but Apple has obviously decided that having a single API available on every iOS device was too big a target to defend. ®