New MFA device registered via Azure AD 'Update user' operation
Detects modifications to a user's Azure Active Directory (Entra ID) authentication methods where a new authentication device is added. The rule specifically monitors changes to 'StrongAuthenticationPhoneAppDetail' or 'StrongAuthenticationUserDetails' and identifies instances where the count of registered devices increases, potentially indicating an attacker adding a device for persistence or MFA bypass.
Splunk (SPL)
