[AC Question]

Every time they I opening something in my phone I have a window that opens with "your phone was attacked by hornyvorm.

[B. Diddy]

Welcome to Android Central! Which phone? Does the popup tell you to install some kind of antivirus app? If so, it's probably a scareware piece of adware that is trying to lure you into installing something that's truly malicious.

Try booting into Safe Mode, which temporarily disables all 3rd party apps. On most Android devices, while powered on, press and hold Power until the Power Off menu appears. Press and hold the Power Off selection until the Safe Mode prompt appears. Tap OK.

If the problem disappears in Safe Mode, then something you installed is causing the problem. You may have to uninstall apps one by one until the problem disappears. If the problem persists in Safe Mode, then it's more likely to be true malware, and might be difficult to get rid of. The first thing to do would be a factory reset.