What is MacOS:Spigot-AY? If your antivirus detects MacOS:Spigot-AY then it indicates that your PC is affected by a potentially unwanted program (PUP). This software is automatically installed, without notification or user consent. Therefore, many users aren’t even aware that their machine has been infected by PUPs. Once started, the MacOS:Spigot-AY will be configured to run