Welcome to Android Central! What is alerting you to the virus, and what's the full name of the suspected malware app? After a quick Google search, it looks like there are various malware apps with a .zzu extension, so simply disabling or forcing it to stop doesn't take away the fact that you have malware on your phone. It's probably best to do a factory reset and set the phone up as a brand new phone (rather than restoring any backups), and then checking to see if it's still there.
That sure seems like malware that may have been installed to the system root. Tap it to show more details -- do you get an option to at least Disable it?
I highly doubt any official system app would open up and say "Hello World" in small text. To be safe, you may want to back up your important data and then do a factory reset. Then set the phone up fresh (rather than restoring the system settings and apps from a prior backup), and see if that app is still there.
I did a factory reset and did not do a restore that but it just reappeared again. Now l have disabled it and no popups or ads have come up ever since. Thanks Mr Senior Ambassador