The M365 Copilot Failed Authentication Patterns rule is designed to detect potential credential attacks or account compromises involving users of Microsoft 365 Copilot. It focuses on analyzing authentication attempts via the M365 Copilot Graph API, particularly looking for failed login attempts, multi-factor authentication (MFA) errors, and unusual geographical access patterns. This rule aggregates various metrics per user, such as number of cities or countries accessed, unique IP addresses, failed logins that contain "fail" or "error" in their status, and specific MFA failure codes (e.g., error code 50074). A user is flagged as suspicious when they have accessed Copilot from multiple locations or if they have any failed authentication attempts or MFA errors, which could indicate scenarios like credential stuffing, brute force attacks, or attempts to bypass multi-factor authentication measures. The implementation requires proper configuration of the Splunk Add-on for Microsoft Office 365 to collect Azure AD sign-in logs, ensuring authentication and permissions are correctly set. Users may trigger false positives if they travel frequently, experience network issues, or reset passwords during travel.