The "Apple Security Alert" scam popup message below that claims MacOS Warning Alert System has detected spyware, is being used by cybercriminals to trick and frighten potential victims into calling them at this fake Apple technical support telephone number: 877-366-1030.
The Apple Security Alert Scam

Whatever you do, please do not call the telephone number in the message. The number is not associate with Apple, it will connect potential victims to scammers who will pretend to be technical support representatives from Apple. They will ask potential vicitms to disclose their account credentials, usernam and password, which they will use fraudulently.