Multi-factor authentication is the most effective defense against credential stuffing, as a stolen password alone will not grant access.

Dark Web Combo Lists: How to Detect Leaked Credentials - Breachsense

If you are reporting on or responding to the discovery of such a file, follow these industry-standard security practices:

Use tools like Have I Been Pwned to check if specific email addresses have been included in known "combo" breaches.

These are usually plain text files formatted as email:password . They may include millions of entries from multiple historical breaches, such as the Anti Public Combo List .