Downloading or installing apps from any external source may be dangerous and hazardous to your Android device as these may either contain virus or some of their files may be conflicting with the files of your Android device. This conflict of the hazardous files or virus may destroy whole of your Android OS and your device may stop functioning, resulting in requiring you to reset the factory reset.
It is a better idea to verify the suitability and virus-free & non-conflicting files of any new app which you want to install in your Android device before installation in OS of your Android device.
Being very careful to such non-functional apps, Android has an in-built app verification feature which, if activated, can warn you or even disallow you to install the dangerous app in your device.
You may activate such feature, easily, and if you feel any problem, do not hesitate to consult the instructions.
Instructions
Command Line: Settings – HOME > Security – PERSONAL > Verify apps – DEVICE ADMINISTRATION.
1: Tap icon of ‘Settings’ on the HOME screen of your Android 4.4.4 KitKat device to open up the ‘Settings’ screen.
2: Scroll down to the PERSONAL section and tap the ‘Security’. 
3: At the ‘Security’ screen, scroll down to the DEVICE ADMINISTRATION section and see the ‘Verify apps’ is not checked, i.e. this feature of disallowing or warning you before installation of harmful apps in your system is not activated. 
4: Tap to check and activate the ‘Verify app’. 
Now, Android KitKat OS will warn you or in extreme conditions, may disallow you to install those apps which may cause harm to your Android device. It is better to avoid such apps.
That’s all!