Why is my menu and back key not working properly?

Hello everyone.

I own a Samsung Galaxy Tab 3, SM-T210r to be precise. Recently, my back and menu button act erratically, like they're randomly being pressed and held when I'm not really doing anything.

I just locked my device then unlock it again to return it to normal, but after doing this repeatedly the problem became consistent and not random anymore.

I restarted my tab. I did a 'soft reset' (turned it off for few hours) and now the back and menu key doesn't even work anymore.

When I touch the keys, the tablet acts as if I'm touching the display just above it. I know because there's a shortcut app just above the back/menu key and they open when I touch the key.

Are you people familiar with this problem? Is this a malware or hardware malfunction? I'm watching some Youtube videos when the problem started and did not install nor downloaded anything for the past week. I just want to make sure before I reset my tab to factory setting as I have important data in it. Thanks!