by Dave LeClair
March 25, 2012
Hacker iH8Snow is known for making some incredible contributions to the jailbreak scene, and now he has come along with another huge one. He tweeted about an exploit he discovered in Apple's appticket system that will allow users to revert their iOS devices with A5 chips back to iOS 5.0.1. His previous contributions to the scene include Sn0wBreeze, iFaith, and F0recast.
Just as it always has been when reverting an iDevice back to a previous version of its firmware, you will need to have your SHSH blobs stored for the older version of the firmware. Devices featuring the A5 chipset are notoriously hard to revert back, even with SHSH blobs. This new exploit could change that completely. Before this loophole, users who accidentally upgraded would be stuck waiting for a jailbreak to launch for iOS 5.1, and if the struggle to jailbreak iOS 5 and 5.0.1 on A5 devices is any indication, that could be a very long wait. This doesn't mean you should go ahead and update your device just because you may be able to bring it back. If you are sitting on iOS 5.0.1, you should be happy and enjoy the pleasant experience of owning a jailbroken iOS device. Even though he had success reverting his device back, it does not necessarily mean it will work for everyone. Sadly, this will not help users who purchase a new device with iOS 5.1 already installed, as their SHSH blobs will not be stored for iOS 5.0.1. If you are one of these poor souls, you will have to wait until they figure out an exploit to jailbreak the latest firmware. At this point, we only have this tweet to work with, and he has not said when this will be made available to the general public. Still, for users who made this fatal upgrade mistake, it is fantastic to know that the end of being stuck with an unjailbroken device is in sight. Source: iJailbreak
Found a loophole in Apple's apticket system. Restored my iPad 2 to 5.0.1 from 5.1. Works on all A5 devices. :)— iH8sn0w (@iH8sn0w) March 25, 2012