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Bryan M. Wolfe
| June 27, 2011
Apple To Take New Measures Against Firmware Downgraders
Apple may be the in process of making it more difficult for users to jailbreak their iDevices. Beginning with iOS 5, Cupertino is said to be adding an additional layer of security that kicks in when a user attempts to restore to a previous firmware version using SHSH blobs, according to the DEV-TEAM BLOG. For those unfamiliar, Apple does not allow users to downgrade their iDevices to previous iOS versions. For example, whenever an iDevice is connected to iTunes, Apple checks its version against the most current version residing on Apple servers. If the iDevice is in need of an upgrade, iTunes will alert the user with instructions on how to upgrade their iPhone or iPad. In this case, Apple tells iTunes it is okay to upgrade. Conversely, a user who attempts to downgrade an iDevice, will receive a message from Apple indicating that isn’t possible. For a jailbreaker, however, downgrading is sometimes necessary. And this is where SHSH blobs come in. They essentially trick Apple into allowing iTunes to downgrade your iDevice. Acording to DEV-TEAM BLOG, however, the days of using SHSH blobs might be coming to an end, or at least make it more difficult. They state:
This will only affect restores starting at iOS5 and onward, and Apple will be able to flip that switch off and on at will (by opening or closing the APTicket signing window for that firmware, like they do for the BBTicket). geohot’s limera1n exploit occurs before any of this new checking is done, so tethered jailbreaks will still always be possible for devices where limera1n applies. Also, restoring to pre-5.0 firmwares with saved blobs will still be possible (but you’ll soon start to need to use older iTunes versions for that). Note that iTunes ultimately is *not* the component that matters here..it’s the boot sequence on the device starting with the LLB.They conclude with these important words:
Note: although there may still be ways to combat this, a beta period is really not the time or place to discuss them. We’re just letting you know what Apple has already done in their exisiting beta releases — they’ve stepped up their game!In other words, the DEV-TEAM could figure out a way to "fix" Apple's changes once implemented so hang tight. Therefore, this probably doesn't mean there will no longer be jailbreaks. Rather, they might be more difficult to figure out. Thoughts?