Device "rooted" security message

[Amjoba]

I have a no-name netbook, which comes up as "WM8850-mid." I only install apps from Google Play or Amazon App Store, and recently installed a Pacman game, apparently from GP. Yesterday, I noticed my netbook was going really slow; from prior exp with viruses, I got a bad feeling. Ran my antivirus, and found a "vulnerability," namely my settings allowed apps from unknown sources. I turned that off. The Pacman game froze and I decided to unistall it, only to find that it didn't show up on my Apps list! When I went back to Google Play, this Pacman doesn't appear among the many iterations of the game that are listed.???

I removed the icon from my desktop, but of course, that doesn't remove the app. Concerned about my banking, etc., I installed Trusteer Mobile, which scanned my device and announced that "device appears to be rooted. Do not use for online banking or other sensitive transactions."

How do I fix this? Will a factory default do it? If so, when I reinstall apps, change passwords, etc., how do I know if something has been compromised? If default won't fix it, then what?

 

[Hadron]

"rooted" means that the OS allows you to run apps as "administrator" in Windows jargon. That's all. Most android devices need modifying to allow this (I'm typing on a rooted device, for example), but many no-name devices do come already rooted.

A factory reset will not change this. It will simply erase any user apps, but not anything that's been installed as a system app.

Do you have an app called Superuser or SuperSU? Those act as "gatekeepers", allowing you to control which apps can use root privileges. If not, it might be worth installing one. But it might first be worth doing a test: install an app that needs root (such as Titanium Backup) and see whether it will run? Or install a terminal emulator and type "su", and see whether you get an error message. If these things work then the system may be giving root access without the gatekeeper (i.e. without giving you control), which is not what you want.

Now to be clear, the only thing you've described which gives me any concern is where the Pacman game went. "usb debugging" is a security vulnerability in that it allows someone with a computer, a usb lead, your device and the right software to access the device contents without unlocking the screen. But if nobody has had that physical access it's not an issue. Root allows apps to change things they wouldn't otherwise be able to, but unless you have malware on there and it has root access that's not an issue. And viruses which might affect your Windows system can do nothing to Android.

So it would be good to understand the situation, and give you more control, but you should not worry too much just yet.