Simple Method to Block Apple's Mechanism to Deactivate iPhone Apps

Steve Jobs in an interview with the Wall Street Journal had confirmed the existence of a kill-switch mechanism to deactivate iPhone apps already installed on the iPhone which was discovered by iPhone expert, Zdziarski during his forensic examination of iPhone 3G.

Zdziarski has published a follow-up post on his blog to clarify a few things about Apple's kill-switch mechanism and also published a simple method on how to block it.

Jonathan “NerveGas” Zdziarski has published the iPhone Open Application Development book to develop unofficial native iPhone applications using the iPhone open source tool chain and is also the author of iPhone Forensics. He had recently ported the iPhone Open Source Tool chain to iPhone firmware 2.0.

He had discovered a remote URL during his forensic study of iPhone £G which indicated that Apple has included a mechanism in iPhone firmware 2.0 to deactivate iPhone apps already installed on the iPhone.

Zdziarski has clarified that:

"The locationd cache, stored in /var/root/Library/Caches/locationd/, includes a cached list of unauthorized applications fetched from a URL on Apple's servers during GPS fix. Only a list is downloaded; it doesn't "tell Apple" what applications you are running."

Zdziarski has this to say after Steve Jobs confirmed that the kill-switch mechanism existed:

"Unless the media is misreporting Steve Jobs, he apparently has confirmed the existence of a kill switch that can disable any application. So unless, for some reason, they decided to build two separate mechanisms into the iPhone to do this (of which, the other one is invisible), this one likely feeds a "master" kill switch. Perhaps there is a special setting in the configuration file which can vaporize the app all together. Of course, this is just speculation, but as I said before, it would be irresponsible to have a blacklist, but only use it to kill GPS applications."

He has also posted a simple method for blocking Apple's kill switch, which needs you to jailbreak iPhone using iPhone Dev Team's Pwnage Tool for Mac or WinPwn Tool for Windows and then add the following entry into /etc/host.

127.0.0.1 iphone-services.apple.com

Steve Jobs had clarified that Apple would use it only to remove a malicious program -- as an example a program that stole user's personal data just as we had thought. He has also mentioned:

"Hopefully we never have to pull that lever, but we would be irresponsible not to have a lever like that to pull."

So we would not recommend iPhone users to disable this mechanism, but if you are paranoid about Apple having control over apps running on your iPhone then you know what needs to be done courtesy Zdziarski.

What do you think?

[via Zdziarski's blog]

 

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