Online permission required
After optional online diagnostics are allowed, WM Guard can compare installed plugins with the official WordPress.org Plugin API.
What is evaluated?
WM Guard reports plugins marked as closed/removed in the directory and plugins whose last update there is more than two years old.
Premium and custom plugins
A plugin that was never published in the WordPress.org directory is not treated as a problem merely because the API returns “plugin not found.” This avoids false alarms for premium and custom plugins.
Process
The check can be scheduled in the background, is limited to a bounded number of installed plugins, and is cached for 24 hours.