Open Activity Monitor and look for unfamiliar or unusually high-CPU processes
Check Login Items in System Settings for unknown startup apps
Review Applications, Downloads, and recent files for anything suspicious
Run a reputable Mac antivirus or anti-malware scan
Check browser extensions for unknown or unwanted add-ons
Review Safari, Chrome, or Firefox homepage, search engine, and notification settings
Look for unexpected pop-ups, redirects, or new toolbars in your browser
Check System Settings for unknown profiles, device management, or configuration profiles
Inspect LaunchAgents, LaunchDaemons, and LoginItems for suspicious entries
Verify disk usage and storage for unknown large files or apps
Update macOS and all installed apps to the latest versions
Restart in Safe Mode and see whether suspicious behavior continues
Disconnect from the internet if you suspect active malware
Back up important files before making major changes
Remove suspicious apps, extensions, profiles, and startup items
Change passwords for important accounts if you suspect compromise
If problems persist, reinstall macOS or seek professional help