How to check a Mac for malware

Add the browser's homepage and default search engine to that list. Adware almost always swaps the search to some odd provider, so if your searches suddenly come from something you never picked, that's your clue even if you find nothing else. For anything more stubborn, look in the LaunchAgents folders: Library/LaunchAgents in your home folder and in the main Library. Strange looking .plist files there are how things relaunch after you delete them.

Most Mac malware is adware rather than anything nasty, so look where adware lives: 1. System Settings > General > Login Items. Anything you don't recognise in either list, look it up. 2. Your Applications folder, sorted by date added. 3. Browser extensions in every browser you use. This is the big one. 4. Search Settings for 'Profiles'. Unless it's a work Mac there usually shouldn't be any. macOS also runs its own scanner (XProtect) silently. For a second opinion the free version of Malwarebytes for Mac does a manual scan and you can uninstall it afterwards.