Identify Reused Mobile Numbers in MFA Setup Intune and Entra
Question
Hi All,
Is there a way to find out if a mobile number has been used for other users when setting up their multifactor authentication? Our Support guys often set up new Starters, and (before we started using Temp Access Pass), they used to set up the user’s 2FA on their own and remove it afterward. But I just want to check and make sure none have been forgotten, so is there a way to check if a number is being used?
Posted by Patrick O’Frani in HTMD FB Group
Answers ( 4 )
Yes, you can use PowerShell to check whether a mobile number has been used for multifactor authentication (MFA) in Microsoft Entra ID.
Using PowerShell Script:-
Open PowerShell and follow the below mentioned steps.
1) Install the Microsoft Graph Module (if not already installed):
Command: Install-Module Microsoft.Graph -Scope CurrentUser
2) Connect to Microsoft Graph with necessary permissions:
Commaand : Connect-MgGraph -Scopes “User.Read.All”
3) Run the following script to check if a phone number is assigned to multiple users:
Command : $phoneNumberToCheck = “0123456789” # Replace with the number you want to check
$users = Get-MgUser -All -Property Id,DisplayName,UserPrincipalName,AuthenticationPhone -Filter “authenticationPhone eq ‘$phoneNumberToCheck'”
if ($users) {
$users | Select-Object DisplayName, UserPrincipalName
} else {
Write-Host “No users found with this phone number.”
}
Replied by Jason Loebbaka
Patrick O’Frani, you’ll have to use PowerShell to query the graph. There’s a module to install, and maybe this command does what you’re looking for?
Replied by Patrick O’Frani
Doug Johnson, thanks. What role do I need to be able to access/use it?
Replied by Vijay Shetti
In the Intune portal, go to the Select Users section, select the user, and select Authentication methods. You can view all the required details.
Replied by Doug Johnson
Use the Microsoft Graph PowerShell module to query all users’ authentication methods. If a number is being used, you’ll find it.
Replied by Patrick O’Frani
Doug Johnson, I have never used Graph and don’t know if I can access it. Can PowerShell do this?
Replied by Doug Johnson
Patrick O’Frani, yes. Install the Microsoft Graph PowerShell module. This will change your life. Google some YouTube tutorials on the module. There are also plenty of blog posts.
For more details, see Quick Guide to Enforce Multifactor Authentication MFA for Users – https://www.anoopcnair.com/enforce-multifactor-authentication-mfa-to-users/
Replied by David Olvera
Yes, if you have the phone as a 2FA option(not recommended) and the user set up the phone number, you can find it in entra ID, click on the user, then click on the authentication method, and you will find it.
Replied by Patrick O’Frani
David Olvera, what you wrote is IF the user is known. My question is how to find who is using duplicate numbers.
Replied by Mitchell Scott
You can view a user’s authentication methods via the Azure portal. Is this what you are after?
Replied by Patrick O’Frani
Mitchell Scott, hi, no. Is there a way to determine if users use a particular number in case of duplicates?