Android Trojan removal I have the Android smartphone “Lava Iris 455”. My phone is not rooted. Since last week I installed APK file from some website. After a second day I realize that a trojan is installed on my phone. It is downloading Android apps automatically when data connection is on my phone.

I installed AVG Antivirus from Google Play Store. It is showing following trojan is installed on my phone:


Name : netalpha 3.1.8
package : com.play.photo.json.alpha
location : /system/app/LibsCore.apk
installed Date : 2016/07/19**


AVG antivirus failed to remove this trojan.
Lookout antivirus shows un-installed unsuccessful
After factory reseting, it is getting back again.
I tried manually to force stop service, disable, clear data. it is getting enable automatically.



I searched this problem on Google, but I did not found a solution.

Last option is flash android stock ROM to phone with flashing software.

I have two questions:


How is the trojan installed on /system/app directory even if my phone is not rooted yet?
Obviously, if it installed on System App directory, then it should be removed without rooting my phone.
After reading this, Iwent and saw on my phone that /system/app contains folders for Google apps, more likely the stock apps. 
Make a backup of the phone (backups only include apps from the play store and other data) and wipe it. You may need to obtain an image file for your phone, install a recovery like TWRP or CWM, wipe the system partition, and install the os image and restore.