Important Concepts of Android App Penetration Testing

• Download Mode

The role of the download mode is to update the persistent storage via flashing. Flashing is available in devices through a proprietary and/or fast boot protocol.

When some key combinations are pressed during the booting process, the boot loader works on the download mode rather than the usual boot process of the kernel. 

• NAND Locks

The role of a NAND lock in Android is to prevent users or hackers from creating or writing new code to the system. They can’t make modifications and customizations to the ROM, kernel, and recovery mode of the system.

• Temporary Root

The temporary root provides access to the system through apps until the phone is restarted. Since the access is temporary, it is called temporary rooting. The reason it is preferred is that temporary rooting can be implemented easily. 

• Permanent Root

Carrying out permanent rooting in a system is very complicated. It requires users to either disable the security flags in the baseband or flash the device with a patched boot that doesn’t apply NAND locks. 

Finding permanent root access to Android devices without NAND locks can be achieved if the users have a root shell or soft root. They just need to write code for accessing the system partition. In case the device has a NAND lock, it needs to be removed first.