Repeated Microsoft Authenticator prompts on iPhone when not signing in

Unrequested Microsoft Authenticator prompts generally fall into two categories: legitimate but background sign-ins, or unwanted sign-in attempts. The behavior described should be treated as a security signal, not ignored.

Direct answers to the questions:

• Yes, repeated prompts can be caused by background sign-in attempts from apps or devices that are trying to refresh tokens or maintain sessions. Microsoft Entra multifactor authentication and Authenticator are designed to reduce prompts, especially when using the Authenticator broker on mobile, but some apps and configurations can still generate frequent reauthentications.
• Yes, it can also indicate that someone else is trying to access the account. When Authenticator is configured for MFA via notifications, any interactive sign-in that reaches the MFA step will send a push notification. If a prompt appears that was not initiated, it might be:
  • Someone entering the username and password on another device.
  • An automated or scripted attack trying passwords.
  • A delayed or retried prompt from a previous sign-in.
  In all such cases, any prompt that was not initiated should be denied. The guidance for unexpected prompts is to select Deny; without the correct response and approval, the account remains protected.
• To identify which app or service is triggering the prompts:
  • Open Microsoft Authenticator when a prompt appears and review the sign-in details shown with the notification (for example, account, location, and sometimes app or resource). Authenticator push notifications can include location to provide better sign-in security; this information helps distinguish legitimate background sign-ins from suspicious ones.
  • If the notification shows an unfamiliar location or pattern, treat it as suspicious and deny it.
  • If prompts appear but no notification alert is visible, ensure notifications are enabled and not silent so the details can be seen when they arrive.
• To reduce unnecessary prompts without disabling MFA:
  • Use Microsoft Authenticator as the primary MFA method on mobile devices. For mobile scenarios, Authenticator acts as a broker to other Microsoft Entra ID–federated apps and reduces authentication prompts on the device by enabling better single sign-on and token reuse.
  • Ensure recommended sign-in and session settings are in place on the tenant side (for example, using Conditional Access sign-in frequency policies and single sign-on via managed or seamless SSO). These configurations are designed to balance security and usability and avoid excessive prompts.
  • Avoid using less reliable methods such as SMS where possible, especially if there are delivery issues, and prefer Authenticator notifications or verification codes.

Security-wise, any prompt that is not clearly tied to an action just taken should be denied. If unexpected prompts continue frequently even after confirming device and session settings, it is advisable to review account security (change password, review sign-in logs if available) and contact support or an administrator to investigate possible unauthorized attempts.

References:

• Authentication methods in Microsoft Entra ID - Microsoft Authenticator app
• Reauthentication prompts and session lifetime for Microsoft Entra multifactor authentication
• Using Outlook mobile to sign in