A not so technical explanation of the AnySim issue for the average iphone user

Basically the iPhone has several layers of software much like a computer. The 
OSX based OS runs 
on the iPhone in a reduced version. The software installed in the iphone and 
the basic version of 
the OS can be restored to default using restore in itunes for most cases.

The iPhone also has a baseband which is basically the firmware to the 
modem/voice 
communications and the NVRAM which stores much of the information about the 
phone. The 
NVRAM cannot be edited directly unlike much of the code on the iphone (unless 
one uses ARM 
code much like IPSF does to unlock the phone) and is encrypted.

The Anysim hack exploited a routine check in the 1.0.2 baseband to open a 
backdoor into 
unlocking the phone by answering "yes" to a check routine in the baseband. This 
caused the 
iPhone to unlock but unfortunately taking this shortcut also (reversibly) 
damaged several data 
points by forcing the phone to write several other bogus entries in the seczone 
which stores 
some checks related to the phones IMEI and possibly in the NVRAM. It changes 
sectors 
A003AC88 - A003AD67 and changes your checksum bytes at A003BFFe-f.

When one tries to update to 1.1.1 in itunes the baseband in the iphone is 
updated to a new 
version which has a different set of check routines. When these checks page the 
corrupted data 
in the seczone the iphone's imei is not properly registered by the software 
output and causes the 
phone to "brick". This can be reversed by following the instructions listed on 
the main page of 
the elite team. This allows to REVERSE the update but does NOT FIX the damage 
done by anysim.

The reason that one cannot update to 1.1.1 from 1.0.2 is that until someone 
figures out what the 
damage was done is; it cannot be reversed. This may take some time and is 
probably not 
necessary until the team figures out a way to unlock 1.1.1 since you would not 
be able to use 
your phone on a non ATT sim.

--Gigio

Original issue reported on code.google.com by gdesa...@gmail.com on 16 Oct 2007 at 7:21

colin8208 / iphone-elite

A not so technical explanation of the AnySim issue for the average iphone user #5