A B2C IEF Custom Policy which invokes MFA based on the IP and absolute time window in which the user last did MFA
The sample policy is developed and managed by the open-source community in GitHub. This policy is not part of Azure AD B2C product and it's not supported under any Microsoft standard support program or service. The policy is provided AS IS without warranty of any kind.
MFA IP Timeout - A policy which forces the user to do MFA on 3 conditions:
- The user has newly signed up.
- The user has not done MFA in the last X seconds.
- The user is logging in from a different IP than they last logged in from.
If the users IP address is different to the last logon IP, then the user will do MFA.
If the users IP address is the same as the last logon IP at which they did MFA, then the user will not do MFA unless the user did MFA over 100 seconds ago (default in this example).
This means the users MFA session is absolute, and if the user contiues to logon from the same IP, the user will be prompted to perform MFA after this time period expires.
The absolute time window for which the user must perform MFA after, can be adjusted in seconds by modifying the timeSpanInSeconds paramter in the CompareTimetoLastMFATime technical profile in the TrustFrameworkBase file. It has been set to 100 seconds in this example.