When I opened the app store app on Macbook Pro, it asked me to login in a pop-up box. The strange thing here was: The user ID field was disabled to edit and it had a pre-filled email address which is unknown to me. So that pop-up box had only password field enabled to fill in for an unknown email address.
Is there a way to track where that email was coming from? Does this mean the Macbook Pro device is hacked? What are some measures that can be taken to prevent this?
I have always kept the device locked and secured from public wifi.