This is Apple's stage 2 bootloader for all of the iDevices. It runs what is known as Recovery Mode. It has an interactive interface which can be used over USB or serial.
- iBoot-99 (1A420 a.k.a. Prototype)
- iBoot-159 (1.0.x)
- iBoot-204 (1.1 and 1.1.1 3A109a)
- iBoot-204.0.2 (1.1.1 3A110a)
- iBoot-204.2.9 (1.1.2)
- iBoot-204.3.14 (1.1.3 and 1.1.4)
- iBoot-204.3.16 (1.1.5)
- iBoot-320.20 (2.0.x)
- iBoot-385.22 (2.1 and 2.1.1)
- iBoot-385.49 (2.2 and 2.2.1)
- iBoot-596.24 (3.0 and 3.0.1)
- iBoot-636.65 (3.1 and 3.1.1)
- iBoot-636.66 (3.1.1 7C146 and 3.1.2)
- iBoot-636.66.33 (3.1.3)
Commands used as an exploit vector
- Until 2.0 beta 6, the diags command would jump to code at the address provided to it. For example, if you sent "diags 0x9000000", it would directly jump to the code at written to 0x9000000. There is now a check that only allows engineering devices to utilize this backdoor.
- For firmware 2.1.1, the iPod touch 2G iBoot contains the ARM7 Go command, which could be used to run a payload on the ARM7 in the device.
- For firmware 3.0 and 3.0.1, the iBoot Environment Variable Overflow is used by purplera1n and redsn0w (as of version 0.8) in order to flash an oversized LLB that exploits the 0x24000 Segment Overflow vulnerability.
- For firmware 3.1, 3.1.1, and 3.1.2, the usb_control_msg(0x21, 2) Exploit is used by greenpois0n and blackra1n in order to flash an oversized LLB that exploits the 0x24000 Segment Overflow vulnerability.
There is an open source version of iBoot being made so that Linux on the iPhone will work. You can check out the source here. It is VERY useful if you are ever reversing iBoot and do not feel like finding out what certain hardware registers are yourself.
// n88 0x4FF00000 => 0x0 0x40000000 => 0xC0000000