Apple has claimed that jailbreaking iPhones – that is, altering their software to allow the user to run applications without restrictions – could turn them into tools for deliberately bringing down cellphone networks.
The claims come in a response to a government review which takes place every three years to decide which situations should be exempted from copyright laws. The Electronic Frontier Foundation has filed a request asking that the act of modifying the iPhone’s software should be deemed legal for people who own a handset.
Because the software is licensed (whereas the handset is sold), Apple maintains that modifying the software is a breach of copyright. It rejects the argument that such behavior is covered by section 117 of the US Copyright Act which allows for situations such as installing software on a computer or making a back-up copy to protect against losing it if the computer is damaged.
The most striking note of its response, however, is the claim that jailbreaking makes it easier to access the baseband processor, the component which connects the handset to the network – in this situation, Apple warns that jailbreaking could modify the software controlling this processor and lead to GPS functions failing.
More seriously, it says jailbreaking could make phones more vulnerable to hackers. As they would be able to access the baseband processor, this could let them change the Exclusive Chip Identification (ECID), the number which identifies the handset to the nearest cellphone tower. Apple claims that this creates a risk of two phones with the same ECID connecting to a tower simultaneously, which could potentially see one user unable to make or receive calls. (PC World questions this claim, noting that iPhones have a secondary identification number built into the SIM.)
According to the filing (PDF link), the consequences could be more serious than inconvenience, Apple says somebody hacking into a jailbroken phone and controlling the baseband processor software might also be able to get round limits on the amount of data the handset can send at once. At best this might allow them to evade data call charges. At worst they could deliberately overload the cellphone tower and crash its operating software