Microsoft OAuth authorization for specific user roles - azure-active-directory

Question

I have to limit which users can access an Azure App. For now, only Global Admins can access using this link:
login.microsoftonline.com/common/oauth2/v2.0/authorize?client_id=client_id_goes_here&scope=user.read.all&response_type=code&redirect_uri=https://myredirectbacklink.com/aad/auth&response_mode=query&state=portal&prompt=consent
After redirect back I get Token using
https://login.microsoftonline.com/common/oauth2/v2.0/token and the query contains the same scope as the authorized link.
The flow of the app is the same as documented in Microsoft identity platform and OAuth 2.0 authorization code flow.
My problem is that client wants to allow Billing Admins to access their app. I went through all Graph Permission Scopes, but could not find any related to Billing Admin.
My knowledge of Microsoft's authorization is somewhat limited. I do know that limitations are done by scope. But if it's just link change or is it in Authentication App in Azure (there is one but I don't know how it's related to actual login permissions).
Should I look in a different direction or is it just simply changing the link? Microsoft's documentation didn't help a lot because it's mostly about calendars and other simple stuff.

Answer 1

Careful, requesting a permission that normally requires admin consent and causing the user consent prompt is not the proper way to ensure the user signing in is actually an admin. A non-admin user could simply modify the URL to scope=User.ReadBasic.All and remove prompt=consent. If the user is allowed to consent for User.ReadBasic.All (which is true in many organizations), they'd be able to continue the sign-in. (Or if the organization had granted admin consent for "User.Read.All", the non-admin user would only need to remove prompt=consent.)
If you need to ensure the user is an administrator, you need to explicitly check for directory role assignments.
You can choose from one of three different ways to do this:
You can configure your app to receive the wids claim, which will include the role template IDs of the directory roles for which the user has an active assignment. This is probably the simplest approach.
Using the Azure portal, you can do this under App registrations > (choose your app) > Token configuration > + Add groups claim. You must include "Directory roles" in your selection:
Another option is to a Microsoft Graph API request to check which of a given list of directory roles the user has been assigned:
POST https://graph.microsoft.com/v1.0/me/checkMemberObjects
Content-type: application/json
{
"ids": [
"fdd7a751-b60b-444a-984c-02652fe8fa1c",
"b0f54661-2d74-4c50-afa3-1ec803f12efe"
]
}
A third option is to make a Microsoft Graph API request to list the directory role assignments granted to the user:
GET https://graph.microsoft.com/beta/roleManagement/directory/roleAssignments
?$filter=principalId eq '{id}'
All three of these approaches involve using directory role template IDs to identify the directory role you are checking for. They're all listed here: https://learn.microsoft.com/azure/active-directory/roles/permissions-reference
Some examples you may be interested in:
Application administrator: 9b895d92-2cd3-44c7-9d02-a6ac2d5ea5c3
Cloud application administrator: 158c047a-c907-4556-b7ef-446551a6b5f7
Global administrator: fdd7a751-b60b-444a-984c-02652fe8fa1c
Privileged role administrator: e8611ab8-c189-46e8-94e1-60213ab1f814
Billing administrator: b0f54661-2d74-4c50-afa3-1ec803f12efe
(I included the first four because those are the directory roles which would, by default, be allowed to grant consent for User.Read.All.)

Answer 2

If someone needs solution and uses php:
You can use https://github.com/microsoftgraph/msgraph-sdk-php
$accessToken = 'token from redirect back, called access_token';
$body = [
"ids" => [
"fdd7a751-b60b-444a-984c-02652fe8fa1c",
"b0f54661-2d74-4c50-afa3-1ec803f12efe"
]
];
$graph = new Graph();
$graph->setAccessToken($accessToken);
$user = $graph->createRequest("post", "/me/checkMemberObjects")
->attachBody($body)
->execute();