Where to download stock firmware

Pretty sure you can remove most of these system based viruses by booting the Samsung Galaxy Note 8.0 in safe mode. You do this by force turning off the tablet by holding the Volume down + Home + Power until the screen goes off.

After you've done that immediately turn the tablet back on again but keep tapping your finger on the menu and back button until it shows up Safe mode on the bottom left or right of the tablet. After that you should be able to unlock the tablet then you will need to go into settings > applications > downloaded > Look for the app called 'System update' this is usually what the virus application hides under and uninstall that program. Once it is done uninstalling reboot the tablet and it should be out of safe mode.

Other wise you should be able to perform a wipe data / factory reset via recovery. You do this by force turning off like i said before but this time hold the power button + volume up and home button. Until you get to the recovery menu with blue text usually.

Once you do get there use the volume buttons to navigate the menu and highlight 'Wipe Data / Factory Reset'. Perform this step by using the power button to confirm selections and this will wipe all data and settings on the tablet. Reboot the tablet via recovery then it will take several minutes for it to boot up. Once it boots up, go through the setup dialog and you should be done.

Otherwise if that all fails. You can download the system firmware via Sammobile website which you will need your model number to get the correct firmware and make sure you select the correct region as well.

Once you've downloaded the firmware you will need to use ODIN to flash the firmware onto the tablet and have the tablet booted into download mode via the power + home + volume down and have the tablet plugged into computer via USB. Select AP / PDA and point that to the downloaded firmware.

Make sure you extract the downloaded file first as it comes compressed and the extracted file comes in a .tar format. Make sure you keep the check / tick boxes as is. Do not modify them as it is dangerous to do so. Then click start and wait for it to say green PASS! then it is safe to unplug tablet.

You may need to do wipe data + factory reset after flashing via ODIN if it doesn't boot after several minutes.

The easier way is probably what Abdul suggested if you want to wipe firmware + factory reset at the same time.

Pretty much most if not all websites that host samsung system firmware files are slow. I ended up paying for Sammobile just to get faster download speeds. I somehow managed to obtain lifetime premium account for fast downloads on the Sammobile website.