A full reinstall of iOS--done by putting the device into DRU mode and then entirely re-imaging it over USB with iTunes from a firmware image--really does reinst

A full reinstall of iOS--done by putting the device into DRU mode and then entirely re-imaging it over USB with iTunes from a firmware image--really does reinstall everything on the system that can possibly be changed by anyone (like, excepting code that is so fixed it isn't upgradeable even by Apple)... if anything you sometimes get some settings left around in awkward places for some of the lower-level components (that maybe could be used to smuggle intent or even attacks across the reinstall). iOS is actually really really good about this in comparison to a lot of other devices.