By default, Microsoft 365 allows users to consent to third-party applications accessing their account data directly — without any administrator review. When a user clicks Accept on an OAuth consent prompt, they grant the application access to read their emails, files, calendar, or contacts, depending on what permissions the app requests.
This default creates a significant attack surface. Malicious apps disguised as productivity tools, document viewers, or AI assistants can trick users into granting broad permissions that give the attacker persistent, MFA-bypassing access to the user's data. Unlike credential phishing, this access survives password resets because it is tied to an OAuth token, not a password.
Restricting user consent forces all third-party app authorisations through an administrator review step. This doesn't block legitimate app usage — it adds a human checkpoint before access is granted. For most organisations, this is the right default. The companion control — enabling the admin consent workflow — ensures users still have a path to request app access.
Some organisations have reasons to allow more flexible consent:
The safest default is to disable user consent entirely and redirect all requests through the admin consent workflow. If you allow user consent for verified publisher apps only, ensure that policy is explicitly configured rather than left as an open default.
After enforcing this control, review these related areas: