Why "3C Helper" app is installed into /system

This app does not use root privileges however 3C Toolbox requires root to be able to install it.

In Android 4.4 (KitKat), this system app is also required to gather battery statistics.

This app is used to achieve things that can no longer be done by regular apps on new versions of Android, mostly toggling of specific components including APN and a few others.

Those toggles are mainly used by toggle widgets, but some may be used if you setup specific profiles involving those system switches.

System apps are bound to the permissions they request and cannot acquire root access without your knownledge.

This system app uses the following permissions:

android.permission.WRITE_SECURE_SETTINGS

android.permission.WRITE_SETTINGS

android.permission.MANAGE_USB

android.permission.CHANGE_NETWORK_STATE

android.permission.ACCESS_NETWORK_STATE

android.permission.BATTERY_STATS