ARM7 Go

This exploit is present in 2.1.1 iPod Touch 2G devices, as well as the iBEC / iBSS if you choose to upload it via DFU. It allows the running of unsigned code on the iPod Touch 2G device's ARM7 processor (not the ARM11, mind you).

This exploit cannot be used on an iPhone, iPhone 3G, or iPod touch 1G, nor is there any reason for it to be as they have already been jailbroken.

Credit

chronic / dev team (no collaboration - spotted by each on their own and worked on seperately)

Exploit

There is an ARM7 in the iPod Touch 2G in addition to the main processor, the ARM11. It is on the same address bus, so it has access to everything the ARM11 has access to, such as the AES engine, the PKE accelorator, and such. The actual exploit is that, in the iPod Touch 2G 2.1.1 firmware, they left behind two commands: arm7_stop and arm7_go. They were promptly removed in 2.2. The arm7_go command had no signature checking, permissions checking, or anything like that.

Payload

The command gives the ARM7 the load address (default is 0x09000000) of an "image" you sent it, and it will jump to it. The limitation is, unlike the diags exploit you cannot just pass a patched iBoot or iBEC. You must write a payload for it to run, but one that patches iBEC or iBoot in memory would do fine.

A payload that will patch out signature, range, and permission checks can be found here: http://code.google.com/p/chronicdev/downloads/detail?name=0wnboot.bin&can=2&q=