Intune Data Warehouse application-only authentication

Raksts
12/04/2023

You can set up an application using Microsoft Entra ID and authenticate to the Intune Data Warehouse. This process is useful for websites, apps, and background processes where the application should not have access to user credentials. Using the following steps, you authorize your application with Microsoft Entra ID using OAuth 2.0.

Authorization

Microsoft Entra ID uses OAuth 2.0 to enable you to authorize access to web applications and web APIs in your Microsoft Entra tenant. This guide shows you how to authenticate your application using C#. The OAuth 2.0 authorization code flow is described in section 4.1 of the OAuth 2.0 specification. For more information, see Authorize access to web applications using OAuth 2.0 and Microsoft Entra ID.

Azure KeyVault

The following process uses a private method to process and convert an app key. This private method has been named SecureString. As an alternative, you could use Azure KeyVault to store the app key. For more information, see Key Vault.

Create a Web App

In this section, you provide details about the Web app you would like to point to at Intune. A web app is a client-server application. The server provides the web app, which includes the UI, content, and functionality. This type of app is separately maintained on the Web. You use Intune to grant a web app access to Intune. The data flow is initiated by the web app.

Sign in to the Microsoft Intune admin center.
Select All services > M365 Microsoft Entra ID > Microsoft Entra ID > App registrations.
Click New registration to display the Register an application pane.
In the Register an application pane, add your app details:
- An app name, such as Intune App-Only Auth.
- The Supported account type.
- The Redirect URI of the application. This is the location users automatically navigate to during the authentication process. They are required to prove that they are who they say they are. For more information, see What is application access and single sign-on with Microsoft Entra ID?
Click Register.

Note

Copy the Application (client) ID from the app pane to use later.

Create a key (password)

In this section, Microsoft Entra ID generates a key value for your app.

On the App registrations pane, select your newly created app to display the app pane.
Select Certificates & secrets near the top of the pane to display the Certificates & secrets pane.
Select Client secrets on the Certificates & secrets pane.
Add the key Description and an Expires duration for the key.
Click Add to save and update the application's keys.
You must copy the generated key value (base64 encoded).

Note

The key value disappears after you leave the Certificates & secrets pane. You cannot retrieve the key from this pane later. Copy it to use later.

Grant application permissions

In this section, you grant permissions to the applications.

Select API permissions > Add a permission > Intune > Application permissions.
Choose the get_data_warehouse option (Get data warehouse information from Microsoft Intune).
Click Add permissions.
Click Done from the Add API access pane.
Click Grant admin consent from the API permissions pane and click Yes when promoted to update any existing permissions this application already has.

Generate token

Using Visual Studio, create a Console App (.NET Framework) project that supports the .NET Framework and uses C# as the coding language.

Select File > New > Project to display the New Project dialog box.
On the left, select Visual C# to display all .NET Framework projects.
Select Console App (.NET Framework), add an app name, and then click OK to create the app.
In Solution Explorer, select Program.cs to display the code.
In Solution Explorer, add a reference to the assembly System.Configuration.
In the pop-up menu, select Add > New item. The Add New Item dialog box is displayed.
On the left, under Visual C#, select Code.
Select Class, change the name of the class to IntuneDataWarehouseClass.cs, and click Add.

Add the following code within the Main method:

     var applicationId = ConfigurationManager.AppSettings["appId"].ToString();
     SecureString applicationSecret = ConvertToSecureStr(ConfigurationManager.AppSettings["appKey"].ToString()); // Load as SecureString from configuration file or secret store (i.e. Azure KeyVault)
     var tenantDomain = ConfigurationManager.AppSettings["tenantDomain"].ToString();
     var msalContext = new AuthenticationContext($"https://login.windows.net/" + tenantDomain + "/oauth2/token");

     AuthenticationResult authResult = msalContext.AcquireTokenAsync(
         resource: "https://api.manage.microsoft.com/",
         clientCredential: new ClientCredential(
             applicationId,
             new SecureClientSecret(applicationSecret))).Result;

Add additional namespaces by adding the following code at the top of the code file:
```
 using System.Security;
 using Microsoft.Identity.Client;
 using System.Configuration;
```
Note

You must use the Microsoft Authentication Library (MSAL). For more information, see Update your applications to use Microsoft Authentication Library (MSAL) and Microsoft Graph API.

After the Main method, add the following private method to process and convert the app key:

private static SecureString ConvertToSecureStr(string appkey)
{
    if (appkey == null)
        throw new ArgumentNullException("AppKey must not be null.");

    var secureAppKey = new SecureString();

    foreach (char c in appkey)
        secureAppKey.AppendChar(c);

    secureAppKey.MakeReadOnly();
    return secureAppKey;
}

In the Solution Explorer, right-click on References, then select Manage NuGet Packages.
Search for Microsoft.Identity.Client and install the related Microsoft NuGet package.
In Solution Explorer select and open the App.config file.

Add the appSettings section so that the xml appears as follows:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
    </startup>
    <appSettings>
      <add key="appId" value="App ID created from 'Create a Web App' procedure"/>
      <add key="appKey" value="Key created from 'Create a key' procedure" />
      <add key="tenantDomain" value="contoso.onmicrosoft.com"/>
    </appSettings>
</configuration>

Update the appId, appKey, and tenantDomain values to match your unique app-related values.
Build your app.

Note

To see additional implementation code, see Intune-Data-Warehouse code example.

Next Steps

Learn more about Azure Key Vault by reviewing What is Azure Key Vault?

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