EvilTokens device_code OAuth BEC - refresh token use from new app accessing M365 mail
This rule detects persistent Microsoft 365 access established by an attacker using OAuth refresh tokens, typically following a device_code phishing attack. It correlates three key events: initial device_code sign-ins from non-compliant or non-managed devices, the subsequent consent to a new OAuth application (likely attacker-controlled) from the same user and within a short timeframe, and finally, Microsoft Graph mail API access originating from that newly registered application. This sequence indicates an adversary has successfully phished a user, gained consent for a malicious application, and is now using it to access the user's mailbox data.
Microsoft Sentinel (KQL)
