Anam Hamid posted an article on phonearena about research regarding the ability to compromise iPhones that are powered off. The concept is you can’t remove the iPhone battery and certain services remain on even when a phone is shut off to allow for lost device location technology. On jailbroken iPhones, some of these services could be exploited allowing malware to be planted on the phone, even when powered off. My gut tells me that the reason this won’t work on a non-jailbroken iPhone is those services are isolated from other services running on the phone unless a jailbreak is implemented. I need to look more into it but regardless of why, Adam points out non-jailbroken phones don’t have to worry about this based on this specific research.
You can read about this research HERE. This is yet another reason not to jailbreak an iPhone. If you do, your security goes down the toilet. Especially a widely used jailbreak that has a default admin login. You are essentially begging an attacker to use a default login to access your phone and own you. Don’t do it!