Posted by givinguflac 7 days ago
> BPR, or Boot Process Register, was a feature implemented in iOS 14 in order to additionally secure devices from bootROM based attacks. Crucially, it restricts data access when a device is booted directly from DFU mode, which is required by both checkm8 and usbliter8. In iOS 14 and 15, this manifested as the requirement to disable your passcode when jailbreaking A11 devices with checkra1n/palera1n, and is the reason why A11 devices must be first erased if they previously had a passcode before jailbreaking with palera1n. A10 devices were not affected by this as they had a SEP exploit, known as blackbird, which prevented this issue from arising. We do not have a SEP exploit for A11 and newer.
Right now we only have a reliable jailbreak (checkm8) for up to iOS 18 (and that's only thanks to one iPad model). Some app developers are pretty aggressive about dropping support for older iOS versions.
This affects iPhone XR, XS, 11, SE 2nd gen, and a smattering of iPads. Many of these devices got the iOS 27 beta and will likely see future iOS versions for at least another year or two.
Edit: here's the affected iPads:
* iPad Pro 11" (gen 1-2)
* iPad Pro 12.9" (gen 3-4)
* iPad mini (gen 5)
* iPad Air (gen 3)
* iPad (gen 8-9)
https://support.apple.com/guide/iphone/force-restart-iphone-...
(well, to be honest this is a bad example to show the system is closed, because copy and paste was difficult on linux too during wayland)
Some were dumped via known exploits, but I don't know how A12/A13 were dumped in the first place. I'd guess someone got code exec via fault injection and dumped it out that way, or perhaps just a privately known vuln.
iBoot source code has also been leaked, in the past.
If not, you need to have unbrick-capable DFU straight in BootROM.
Which typically means: ROM code that carries an entire USB stack, as well as means of validating and booting executables from the USB stack.
An alternative would be to have BootROM recovery off MicroSD, but, iPhone lmao. They didn't chase the trend of "no expandable storage" - they created it.