format and install new OS to get rid of viruses

Question

I have an android phone (my uncle's) that is full of viruses that display adds and reinstall themselves I'm guessing there is no important/needed data on the phone

I tried factory reset, after used Dr Web to find viruses, and to root the phone (Kingo ROOT) in order to be able to remove some of them, 2 files identified by drweb couldn't be removed even though the phone was rooted because they were system files (priv-app/baseservice.apk and another one), I renamed them instead.

all this ^ didn't helped completely, they appear again somehow, so would like to format and clean install a new OS

is there a easy way to do that ? my guess is I need some program on my pc (windows7) for this and connect the phone using usb and run some commands

the device is a fake galaxy S6, Android 5.0.2 kernel version 3.10.61

Answer 1

Firstly, some background

• Anti Virus. Android devices are not susceptible to viruses as Windows machines are. To understand more see this Is an antivirus really needed for Android?. So, installing anti virus is not helping any, unless it scans for malware also

• Malware. Malware in Android devices works by losing itself into /system ,i.e., behaving as if it is a system app. Factory Reset does not change anything in /system partition, so it does not help. You could try installing apps suggested here to check for malware Some program is showing ads on my desktop... How can I catch it?. You could read this for tell-tale symtoms of malware

Second, if you have a malware that can't be removed, only thing to do is to flash a new OS or stock OS a you rightly thought. This is going to be a challenge as getting reliable OS may be a challenge and you would need to search in various ROM forums of you can locate one that works on your device.You would find flashing instructions provided with ROM.

Important Note

Any ROM that works on Samsung S6 (Original) won't work on your device and may cause your device to be bricked. Be sure to flash a ROM meant for your device. Please read these to understand

• Can I install a ROM made for a different device?:

• Feasibility of flashing a ROM (meant for original device) on a re-branded device

Is it tough to flash a new ROM? Not really, if you take your time in understanding the instructions IMO, finding a ROM from a reliable source is the biggest challenge. My search (not very thorough) didn't lead me to any source

Answer 2

Things you can do:

1. Downgrade to your stock ROM and install a good antivirus and run a complete device scan because some of them are powerful enough to remove viruses from system files in priveledged user mode.

2. Install Ubuntu Touch instead of android as shown in this guide. The guide is actually primarily for nexus devices but you can make it work for Galaxy S6 by finding the stock ROM yourself and other stuff for the S6 yourself instead of following the links given in the guide which are for nexus devices.

3. If that doesn't work and you are unable to install Ubuntu touch for some reason try this.

Answer 3

I've fixed the phone by rooting it and uninstalling a bunch of system apps (anything that felt suspicious, google helped) , apparently the phone had malware apps preinstalled (root apps),

I also removed the sms app by accident, but it's ok, the owner doesn't use sms