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Knowledgeable Jailbreakers, Give Me Some Insight?

dan448899

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Hey everyone. I've been trying to learn all I can about jailbreaking and how it works, and I'd just like some questions clarified by those who know more about it than I do.

1) What's the difference between a bootrom and userland exploit?
2) Why can't Apple patch bootrom exploits?
3) When your iDevice is jailbroken, what actually happens to allow it to run unauthorized code?
4) What makes an exploit tethered vs. untethered (not the definition, but what about tethered exploits makes them not work on reboot)?
5) How does Semi-tether work?

If anyone could answer any of these questions, it would be much appreciated. As I am not very familiar with highly technical jargon in this area, please try to explain in layman's terms as much as possible.
 

Jmills87

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Welcome, here are some answers:

1) Bootrom exploits exist in the bootrom of the device, they are read-only so they cannot be patched with a software update from Apple. The only way they can patch a bootrom exploit is to manufacture a new hardware revision. That is why these types of exploits are preferred. Userland exploits exist in the firmware itself, they are more common, but are easily patchable by Apple.

2) See #1

3) When your iDevice is jailbroken you have root access to the device(like you do on your computer). Instead of only being able to access specific parts of the filesystem(photos, calendar, etc) you have access to ALL of the files on the filesystem including system files and application files. This is why you can run unsigned code, just like you can run whatever code you want on your computer.

4) It has to do with iBoot which is the bootloader for the iPhone that tells the phone how to load the OS, if it fails this check and detects that the OS is not the official version provided by Apple it will not boot. In an untethered jailbreak they use workarounds to bypass this check by injecting data into the bootloader.

5) It is not 100% clear how it works since it's not open-source, but MobileSubstrate somehow patches the bootloader to allow a normal boot(without the added code to load Cydia services)

Hope that helps
 
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cody3819

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Can anyone tell me why when cydia is trying to load its saying posix error new to jailbreak and wondering if something wrong thanks
 

SERBDVB

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I just delete a few added repos then refresh cydia and re add them after the posix clears. Fix the problem for me
 

cody3819

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I just tried to get on and it's now saying ntb error what's up with that not trying to annoy anyone just new to all this...... And one other thing if u have a tethered jailbreak once a untethered jailbreak comes out can you go untethered?????????
 

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