/Applications/Setup.app

Setup.app running on an iPhone 5

This application uses Framework 7 style and starts automatically after a restore or if lockdownd detects the device to be Unactivated (e.g. by deleting content of activation_records within Lockdown folder, you can trigger this effect).

The file comes as a standard Apple Pre-installed .app file and it draws it's form as a pop up window. While this app is running, the /System/Library/CoreServices/SpringBoard.app app freeze. Apple implemented this to prevent crashes by flooding Setup.app with Emoji keys or by overloading it's browser components with Javascript loops.

As Setup.app is running it's window over /System/Library/CoreServices/SpringBoard.app, crashing this app will leave the /System/Library/CoreServices/SpringBoard.app opened and let the phone be usable as a normal one even if it is not activated (but it has no service)(see Baseband Brickstate).

Crashing this app unlocks /System/Library/CoreServices/SpringBoard.app processes as the crash will entirely close the Setup.

This app is started automatically by lockdownd file, and it's configuration files consists in Com.apple.purplebuddy.plist file that contains Setup.app progress. When setup is finished, this configuration file prevents Setup.app from showing up using these tags:

<key>SetupDone</key>
<true/>
<key>SetupFinishedAllSteps</key>
<true/>

Setting it to false might not trigger the Setup.app as lockdownd finds the activation ticket inside lockdown folder.