Exploiting Password Reuse on Personal Accounts: How to Gain Access to Domain Credentials Without Being on a Target’s Network: Part 1

This article documents a practical attack methodology for obtaining domain user credentials without network access by leveraging breached personal account credentials of an organization’s customers. The author describes collecting ~50,000 leaked customer credentials via PwnedList, correlating personal emails to employees using Pipl, converting names to the corporate email schema, and attempting logins against external services (e.g., OWA) to identify reused passwords and gain domain access, with recommendations to use password managers to reduce reuse.