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Difference between revisions of "GeekGrade"

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Geekgrade Downgrade is currently the only way to downgrade [[idevices]] without [[SHSH]] blobs. It only works on devices with the [[S5L8930]] and [[S5L8920]] chips. It is a tethered downgrade. Found at [http://geeksn0w.it/GeekGrade/].
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'''GeekGrade''' is a [[Tethered Downgrade|tethered downgrade]] for the [[S5L8930]] and [[S5L8920]] chips that does not require [[SHSH]] blobs. It was developed by [https://twitter.com/blackgeektuto BlackGeekTutorial], and was found at [http://geeksn0w.it/GeekGrade/ geeksn0w.it].
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== Exploits used ==
  
== Exploits used ==
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Geekgrade Downgrade uses many exploits together to create a tethered downgrade without [[SHSH]] blobs.They happen in this order:
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GeekGrade uses many exploits together to create a tethered downgrade without [[SHSH]] blobs. They happen in this order:
   
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1.[[Limera1n]]- the bootrom exploit that allows pwned dfu mode. Pwned dfu mode puts the device in a state where custom firmware files can be falsely checked as legit when itunes restores to a custom firmware
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1.[[limera1n]] - the bootrom exploit that allows pwned [[DFU Mode]]. Pwned DFU mode puts the device in a state where custom firmware files can be falsely checked as legitimate when [[iTunes]] restores to a custom firmware
   
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2.Custom firmware- This only works because iTunes originally only asked the [[idevice]] if the firmware was legitimitley from apple. Apple firmware has specific img3 hashes, and itunes asks the [[idevice]] if it will accept them. Well, pwned dfu just tells it yes. The custom firmware uses [[SHSH]] blobs "donated for the project" and although they dont match the device, [[limera1n]] bypasses ios's verification for legit blobs.
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2.Custom firmware - This only works because iTunes originally only asked the device if the firmware was legitimately from Apple. Apple firmware has specific img3 hashes, and iTunes asks the device if it will accept them. Pwned DFU mode allows the device to 'say yes'. The custom firmware uses [[SHSH]] blobs "donated for the project" and although they don't match the device, [[limera1n]] bypasses iOS' verification for correct blobs.
   
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3.iTunes 11.0-All itunes versions below 11.1 can be exploited with pwned dfu to restore to a custom firmware. This is because itunes previously only asked the [[idevice]] if the hashes were correct. All versions above 11.0.5 will recalculate the hash and check it again before restoring.
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3.[[iTunes]] 11.0 - All iTunes versions below 11.1 can be exploited with pwned DFU mode to restore to a custom firmware. This is because iTunes previously only asked the device if the hashes were correct. All versions above 11.0.5 will recalculate the hash and check it again before restoring.
   
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4.[[Limera1n]]-everytime the device is boot tethered, the exploit bypasses [[SHSH]] blobs verification, allowing it to boot.
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4.[[limera1n]] - everytime the device is booted tethered, the exploit bypasses [[SHSH]] blobs verification, allowing it to boot.
   
   
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- iOS 5.1.1
 
- iOS 5.1.1
   
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iPod Touch 4G (iPod4,1)
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iPod touch (4th generation) (iPod4,1)
 
- iOS 6.1.3
 
- iOS 6.1.3
 
- iOS 6.1 1
  
- iOS 6.1 1
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- iOS 4.1
 
- iOS 4.1
   
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iPad 1 (iPad1,1)
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iPad (iPad1,1)
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- iOS 3.2
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- iOS 3.2
   
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[[Category:Downgrading]]
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iPhone 3GS- the old bootrom on the 3GS is exploitable with the [[0x24000 Segment Overflow]]. This can be used to load [[limera1n]] and bypass [[SHSH]] blob verification completley, meaning an untethered downgrade. The new bootrom is only exploitable to [[limera1n]] meaning like all other [[limera1n]] devices it must be loaded by redsnow each and every time to boot. As of 2016, no 3GS ispws have been created for geekgrade, although they could be.
  

Latest revision as of 10:59, 12 April 2017

GeekGrade is a tethered downgrade for the S5L8930 and S5L8920 chips that does not require SHSH blobs. It was developed by BlackGeekTutorial, and was found at geeksn0w.it.

Exploits used

GeekGrade uses many exploits together to create a tethered downgrade without SHSH blobs. They happen in this order:

1.limera1n - the bootrom exploit that allows pwned DFU Mode. Pwned DFU mode puts the device in a state where custom firmware files can be falsely checked as legitimate when iTunes restores to a custom firmware

2.Custom firmware - This only works because iTunes originally only asked the device if the firmware was legitimately from Apple. Apple firmware has specific img3 hashes, and iTunes asks the device if it will accept them. Pwned DFU mode allows the device to 'say yes'. The custom firmware uses SHSH blobs "donated for the project" and although they don't match the device, limera1n bypasses iOS' verification for correct blobs.

3.iTunes 11.0 - All iTunes versions below 11.1 can be exploited with pwned DFU mode to restore to a custom firmware. This is because iTunes previously only asked the device if the hashes were correct. All versions above 11.0.5 will recalculate the hash and check it again before restoring.

4.limera1n - everytime the device is booted tethered, the exploit bypasses SHSH blobs verification, allowing it to boot.


Exploitable Devices and Compatible Firmware

iPhone 4 (iPhone3,1) - iOS 6.1.2 - iOS 6.1 - iOS 5.1.1 - iOS 5.1 - iOS 5.0.1 - iOS 4.3.5 - iOS 4.3.4 - iOS 4.3.3 - iOS 4.3.1 - iOS 4.1 - iOS 4.0.2

iPhone 4 (iPhone3,2) - iOS 6.1.3

iPhone 4 (iPhone3,3) - iOS 6.1.3 - iOS 5.1.1

iPod touch (4th generation) (iPod4,1) - iOS 6.1.3 - iOS 6.1 1 - iOS 6.0 - iOS 5.1.1 - iOS 5.1 - iOS 5.0.1 - iOS 4.3.5 - iOS 4.3.3 - iOS 4.1

iPad (iPad1,1) - iOS 3.2

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