How to Programmatically Clear or Update a Phone Number for Azure AD B2C MFA
Multi-factor authentication (MFA) is crucial for securing your Azure AD B2C applications. Phone-based MFA offers a convenient and secure way to verify user identities. However, scenarios may arise where you need to programmatically clear or update a user's phone number associated with their Azure AD B2C account. This article guides you through the process, offering practical solutions and insights.
Understanding the Challenge
Imagine a scenario where a user changes their phone number. You need to update this change within their Azure AD B2C account to ensure they can still receive MFA verification codes. Similarly, if a user no longer wants to use phone-based MFA, you might need to clear their phone number from the account.
Original Code (Illustrative)
Let's consider a hypothetical code snippet using the Microsoft Graph API to update a user's phone number:
using Microsoft.Graph;
// ... (Authentication and Graph client setup)
// Get the user object
var user = await graphClient.Users["userPrincipalName"].Request().GetAsync();
// Update the phone number
user.MobilePhone = "newPhoneNumber";
// Update the user object in Azure AD B2C
await graphClient.Users["userPrincipalName"].Request().UpdateAsync(user);
This code snippet demonstrates the general concept of updating a user's phone number using the Graph API. However, it's important to note that Azure AD B2C doesn't directly expose a dedicated API endpoint for managing phone numbers used for MFA.
Unique Insights and Practical Solutions
-
Leverage User Profile Attributes: The
MobilePhoneattribute available through the Graph API is primarily intended for storing a user's primary phone number. It's not explicitly designed for managing MFA phone numbers. -
Custom User Attributes: You can introduce a custom user attribute to store the phone number specifically used for MFA. This custom attribute would be under your control, allowing you to manage it programmatically.
-
Integration with Your User Management System: The ideal approach is to tie your MFA phone number management into your existing user management system. This ensures consistency and simplifies the process. If you're using an identity provider (IdP) like Azure AD, you can manage MFA settings within your IdP configuration.
Implementing the Solution
Using Custom User Attributes:
-
Create a Custom Attribute: Define a custom user attribute named
MfaPhoneNumberin your Azure AD B2C tenant to store the dedicated MFA phone number. -
Update Attribute Value: Utilize the Graph API to update this custom attribute with the new phone number:
user.SetCustomAttribute("MfaPhoneNumber", "newMfaPhoneNumber");
- MFA Configuration: Configure your MFA policies to use the
MfaPhoneNumberattribute when sending verification codes.
Integration with User Management System:
-
Synchronize Data: Ensure your user management system seamlessly synchronizes data with Azure AD B2C, including MFA phone numbers. This could involve using APIs or integration tools.
-
Update MFA Settings: Utilize your user management system's APIs or UI to manage MFA phone numbers directly within your system.
Conclusion
While Azure AD B2C doesn't provide a dedicated API for managing MFA phone numbers directly, you can leverage custom user attributes or integrate with your user management system for programmatic control. By implementing these solutions, you can effectively update or clear phone numbers associated with Azure AD B2C MFA, maintaining user security and usability.
Additional Resources:
