Modern Authentication, Legacy Problems
Field note from an incident response case in a hybrid on-premises Exchange environment where Hybrid Modern Authentication and Entra MFA were enforced, yet 66,610 EWS requests from a Thunderbird user-agent authenticated with NTLM. OWA also accepted forms-based authentication directly. It shows how to find these paths in Exchange HttpProxy logs, check virtual directories and authentication policies, and block legacy authentication.
Blue Team & Detection, Identity & Access· Published and added 1 Nov 2026


























































































.png)







