Set up a cron job or use a monitoring tool (e.g., Splunk, Datadog, or a simple Python script) to scan your own domains for the exact string intitle:index of secrets new as it applies to your site. Use Google Alerts with: site:yourdomain.com intitle:"index of" secrets
Many users use this to find PDFs, movies, or MP3s hosted on open servers. intitle index of secrets new