README.md

React single-page application calling Express web API using Conditional Access auth context to perform step-up authentication

1. Overview
2. Scenario
3. Contents
4. Prerequisites
5. Setup
6. Registration
7. Running the sample
8. Explore the sample
9. About the code
10. More information
11. Community Help and Support
12. Contributing

Overview

This sample demonstrates how to use the Conditional Access Authentication Context feature to achieve granular access control and demand a higher bar of authentication for certain sensitive operations (e.g. HTTP DELETE requests) on an Express.js protected web API called by a client React single-page application (SPA).

The web API is protected using passport-azure-ad, while the admin panel on the web API is implemented using microsoft-identity-express to acquire access tokens and Microsoft Graph JavaScript SDK for querying Microsoft Graph. For storing data, the Azure Cosmos DB API for MongoDB is used. Finally, the client React SPA acquires access tokens using the Microsoft Authentication Library for React.

ℹ️ Check out the recorded session on this topic: Use Conditional Access Auth Context in your app for step-up authentication

Scenario

1. The client React SPA uses the MSAL React to sign-in and obtain a JWT access token from Azure AD.
2. The access token is used as a bearer token to authorize the user to call the Express web API protected by Azure AD.
3. For sensitive operations, the web API is configured to demand step-up authentication, like MFA, from the signed-in user.

Contents

File/folder	Description
SPA/src/authConfig.js	Authentication parameters for SPA project reside here.
SPA/src/index.js	MSAL React is initialized here.
SPA/src/fetch.js	Claims challenge for the client is handled here.
API/.env	Authentication parameters for the web API project.
API/auth/routeGuard.js	Custom middleware protecting app routes
API/auth/claimsManager.js	Custom middleware handling checking for auth context and generating claims challenge.
API/app.js	passport-azure-ad is initialized here.

Prerequisites

• An Azure AD tenant. For more information see: How to get an Azure AD tenant
• A user account in your Azure AD tenant. This sample will not work with a personal Microsoft account. Therefore, if you signed in to the Azure portal with a personal account and have never created a user account in your directory before, you need to do that now.
• Azure AD premium P1 is required to work with Conditional Access policies.
• An Azure CosmosDB API for MongoDB instance is required to. See how to create here one here.

Setup

Step 1: Clone or download this repository

From your shell or command line:

git clone https://github.com/Azure-Samples/ms-identity-javascript-react-tutorial.git

or download and extract the repository .zip file.

⚠️ To avoid path length limitations on Windows, we recommend cloning into a directory near the root of your drive.

Step 2. Install Express web API dependencies

    cd ms-identity-javascript-react-tutorial
    cd 6-AdvancedScenarios/3-call-api-acrs/API
    npm install

Step 3. Install React SPA dependencies

    cd ../
    cd SPA
    npm install

Create an Azure Cosmos DB for MongoDB instance

ℹ️ See the tutorial on Quickstart: Azure Cosmos DB MongoDB API for JavaScript with MongoDB driver. Below we summarize the required steps.

1. From the Azure portal menu or the Home page, select Create a resource.
2. On the New page, search for and select Azure Cosmos DB.
3. On the Select API option page, select the Azure Cosmos DB API for MongoDB option.
4. In the Create Azure Cosmos DB Account page, enter the basic settings for the new Azure Cosmos account (Subscription, Resource Group, Account Name etc.).
5. Once you are done, select Review + create and your MongoDB instance will be created.
6. Navigate to your newly created Azure CosmosDB resource, and select the Connection String blade to the left.
7. Copy and note down the primary connection string, which you will use later in sample configuration parameters.

Register the sample application(s) with your Azure Active Directory tenant

There are two projects in this sample. Each needs to be separately registered in your Azure AD tenant. To register these projects, you can:

• follow the steps below for manually register your apps
• or use PowerShell scripts that:
  • automatically creates the Azure AD applications and related objects (passwords, permissions, dependencies) for you.
  • modify the projects' configuration files.

Expand this section if you want to use this automation:

⚠️ If you have never used Azure AD Powershell before, we recommend you go through the App Creation Scripts once to ensure that your environment is prepared correctly for this step.

1. On Windows, run PowerShell as Administrator and navigate to the root of the cloned directory

2. If you have never used Azure AD Powershell before, we recommend you go through the App Creation Scripts once to ensure that your environment is prepared correctly for this step.

3. In PowerShell run:

   Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope Process -Force

4. Run the script to create your Azure AD application and configure the code of the sample application accordingly.

5. In PowerShell run:

   cd .\AppCreationScripts\
   .\Configure.ps1

   Other ways of running the scripts are described in App Creation Scripts The scripts also provide a guide to automated application registration, configuration and removal which can help in your CI/CD scenarios.

Choose the Azure AD tenant where you want to create your applications

As a first step you'll need to:

1. Sign in to the Azure portal.
2. If your account is present in more than one Azure AD tenant, select your profile at the top right corner in the menu on top of the page, and then switch directory to change your portal session to the desired Azure AD tenant.

Register the service app (msal-node-api-acrs)

1. Navigate to the Azure portal and select the Azure AD service.

2. Select the App Registrations blade on the left, then select New registration.

3. In the Register an application page that appears, enter your application's registration information:

   • In the Name section, enter a meaningful application name that will be displayed to users of the app, for example msal-node-api-acrs.
   • Under Supported account types, select Accounts in this organizational directory only.
   • In the Redirect URI (optional) section, select Web in the combo-box and enter the following redirect URI: http://localhost:5000/admin.

     Note that there are more than one redirect URIs used in this sample. You'll need to add them from the Authentication tab later after the app has been created successfully.

4. Select Register to create the application.

5. In the app's registration screen, find and note the Application (client) ID. You use this value in your app's configuration file(s) later in your code.

6. In the app's registration screen, select Authentication in the menu.

   • If you don't have a platform added, select Add a platform and select the Web option.
   • In the Redirect URIs section, enter the following redirect URIs.
     • http://localhost:5000/admin/redirect

7. Select Save to save your changes.

8. In the app's registration screen, select the Certificates & secrets blade in the left to open the page where we can generate secrets and upload certificates.

9. In the Client secrets section, select New client secret:

   • Type a key description (for instance app secret),
   • Select one of the available key durations (6 months, 12 months or Custom) as per your security posture.
   • The generated key value will be displayed when you select the Add button. Copy and save the generated value for use in later steps.
   • You'll need this key later in your code's configuration files. This key value will not be displayed again, and is not retrievable by any other means, so make sure to note it from the Azure portal before navigating to any other screen or blade.

10. In the app's registration screen, select the API permissions blade in the left to open the page where we add access to the APIs that your application needs.

    • Select the Add a permission button and then,
    • Ensure that the Microsoft APIs tab is selected.
    • In the Commonly used Microsoft APIs section, select Microsoft Graph
    • In the Delegated permissions section, select the Policy.Read.ConditionalAccess, Policy.ReadWrite.ConditionalAccess in the list. Use the search box if necessary. Note: The Graph permission, **Policy.ReadWrite.ConditionalAccess** is required for creating new auth context records by this sample. In production, the permission, **Policy.Read.ConditionalAccess** should be sufficient to read existing values and thus is recommended.
    • Select the Add permissions button at the bottom.
    • Select Grant admin consent for (your tenant).

11. In the app's registration screen, select the Expose an API blade to the left to open the page where you can declare the parameters to expose this app as an API for which client applications can obtain access tokens for. The first thing that we need to do is to declare the unique resource URI that the clients will be using to obtain access tokens for this Api. To declare an resource URI, follow the following steps:

    • Select Set next to the Application ID URI to generate a URI that is unique for this app.
    • For this sample, accept the proposed Application ID URI (api://{clientId}) by selecting Save.

12. All APIs have to publish a minimum of one scope for the client's to obtain an access token successfully. To publish a scope, follow the following steps:

    • Select Add a scope button open the Add a scope screen and Enter the values as indicated below:
      • For Scope name, use access_as_user.
      • Select Admins and users options for Who can consent?.
      • For Admin consent display name type Access msal-node-api-acrs.
      • For Admin consent description type Allows the app to access msal-node-api-acrs as the signed-in user.
      • For User consent display name type Access msal-node-api-acrs.
      • For User consent description type Allow the application to access msal-node-api-acrs on your behalf.
      • Keep State as Enabled.
      • Select the Add scope button on the bottom to save this scope.

13. Select the Manifest blade on the left.

    • Set accessTokenAcceptedVersion property to 2.
    • Set the optionalClaims property as shown below to request client capabilities claim xms_cc:

    "optionalClaims": 
    {
      "accessToken": [
        {
          "additionalProperties": [],
          "essential": false,
          "name": "xms_cc",
          "source": null
        }
      ],
      "idToken": [],
      "saml2Token": []
    }

    • Click on Save.

Configure the service app (msal-node-api-acrs) to use your app registration

Open the project in your IDE (like Visual Studio or Visual Studio Code) to configure the code.

In the steps below, "ClientID" is the same as "Application ID" or "AppId".

1. Open the API\.env file.
2. Find the string Enter_the_Tenant_Info_Here and replace the existing value with your Azure AD tenant ID.
3. Find the string Enter_the_Application_Id_Here and replace the existing value with the application ID (clientId) of msal-node-api-acrs app copied from the Azure portal.
4. Find the string Enter_the_Client_Secret_Here and replace the existing value with the client secret you recorded earlier.
5. Find the string Enter_Database_Connection_String_Here and replace the existing value with the connection string of your Azure CosmosDB instance.
6. Find the string ENTER_YOUR_SECRET_HERE and replace the existing value with a secret that will be used when encrypting your app's session using the express-session package.

Register the client app (msal-react-spa-acrs)

1. Navigate to the Azure portal and select the Azure AD service.
2. Select the App Registrations blade on the left, then select New registration.
3. In the Register an application page that appears, enter your application's registration information:
   • In the Name section, enter a meaningful application name that will be displayed to users of the app, for example msal-react-spa-acrs.
   • Under Supported account types, select Accounts in this organizational directory only.
   • In the Redirect URI section, select Single-page application in the combo-box and enter the following redirect URI(s):
     • http://localhost:3000/
     • http://localhost:3000/redirect.html
4. Select Register to create the application.
5. In the app's registration screen, find and note the Application (client) ID. You use this value in your app's configuration file(s) later in your code.
6. In the app's registration screen, select the API permissions blade in the left to open the page where we add access to the APIs that your application needs.
   • Select the Add a permission button and then,
   • Ensure that the My APIs tab is selected.
   • In the list of APIs, select the API msal-node-api-acrs.
   • In the Delegated permissions section, select the Access 'msal-node-api-acrs' in the list. Use the search box if necessary.
   • Select the Add permissions button at the bottom.

Configure the client app (msal-react-spa-acrs) to use your app registration

Open the project in your IDE (like Visual Studio or Visual Studio Code) to configure the code.

In the steps below, "ClientID" is the same as "Application ID" or "AppId".

1. Open the SPA/src/authConfig.js file.
2. Find the string Enter_the_Application_Id_Here and replace it with the application ID (clientId) of msal-react-spa-acrs app copied from the Azure portal.
3. Find the string Enter_the_Tenant_Info_Here and replace it with your Azure AD tenant ID.
4. Find the string Enter_the_Web_Api_Scope_here and replace it with the scope of msal-node-api-acrs that you've exposed earlier, e.g. api://API_CLIENT_ID/access_as_user.

Running the sample

Start the web API first:

    cd API
    npm start

In a separate terminal, type

    cd SPA
    npm start

Explore the sample

1. We'd first replicate the experience of an admin configuring the auth contexts. For that, browse to http://localhost:5000/admin and sign-in using a tenant admin account. Click on the Dashboard link on the menu.

2. As a first step, you will ensure that a set of auth contexts is already available in this tenant. Click the Create or Fetch button to check if they exist. If they don't, the code will create three example auth context entries for you. These three entires are named Require strong authentication, Require compliant devices and Require trusted locations.

ℹ️ The Graph permission Policy.ReadWrite.ConditionalAccess is required for creating new records. In production, the permission Policy.Read.ConditionalAccess should be sufficient to read existing values and thus is recommended.

Select an operation in the web API and an auth context value to apply. Then select Save or Update. This updates this mapping in the local app's database. We advise you use the same auth context value for operations if possible, as this ensures that the user is redirected to Azure AD just once to perform the step-up authN.

⚠️ When changing auth context mappings, have the user sign-out and sign-back in for the changes to take effect.

3. Go to Details page to get details of data saved on the web API side in its database. You can select Delete if you need to delete a mapping from the local database.

The web API is now ready to challenge users for step-up auth for the selected operations.

Configure a conditional access policy to use auth context in Azure portal

1. Navigate to Azure Active Directory > Security > Conditional Access
2. Select New policy and go to Cloud apps or actions. In dropdown select Authentication context. The newly created auth context values will be listed for you to be used in this CA policy.

Select the value and create the policy as required. For example, you might want the user to satisfy a MFA challenge if the auth context value is Require strong authentication.

Test in the client app

1. Browse http://localhost:3000 and sign-in.
2. Select TodoList page and perform the operations.
   • If an operation was saved for a certain authContext and there is a CA policy configured and enabled, the user will be redirected to Azure AD and ask to perform the required step(s) like MFA.

ℹ️ Did the sample not work for you as expected? Then please reach out to us using the GitHub Issues page.

We'd love your feedback!

ℹ️ Consider taking a moment to share your experience with us

About the code

Checking for client capabilities

The client capabilities claim (xms_cc) indicate whether a client application can satisfy the claims challenge generated by a conditional access policy. To obtain this claim in an access token, we enable the clientCapabilities configuration option in authConfig.js:

const msalConfig = {
    auth: {
        clientId: 'Enter_the_Application_Id_Here', 
        authority: 'https://login.microsoftonline.com/Enter_the_Tenant_Info_Here',
        redirectUri: "/redirect", 
        postLogoutRedirectUri: "/",
        navigateToLoginRequestUrl: true, 
        clientCapabilities: ["CP1"] // this lets the resource owner know that this client is capable of handling claims challenge.
    }
}

const msalInstance = new PublicClientApplication(msalConfig);

Checking for auth context

In app.js, we add custom a routeGuard middleware to handle incoming requests web API's todolist endpoints:

app.use('/api',
    passport.authenticate('oauth-bearer', { session: false }), // validate access tokens
    routeGuard, // check for auth context
    todolistRoutes
);

The routeGuard middleware checks the database for any auth context entries, and inspects the access token in the authorization header of the incoming request to see if it contains the necessary claims. If it does, it passes the request to the next middleware in chain. If it doesn't, the checkForRequiredAuthContext middleware takes over. This is shown in routeGuard.js:

const authContextGuard = (req, res, next) => {
    const acrs = AuthContext.getAuthContexts(); // get the current auth contexts from db

    // if there is no auth context in the db, let the request through
    if (acrs.length === 0) {
        return next();
    } else {
        const authContext = acrs.find(ac => ac.operation === req.method && ac.tenantId === req.authInfo.tid); 

        if (!!authContext) {
            // if found, check the request for the required claims
            return checkForRequiredAuthContext(req, res, next, authContext.authContextId);
        }

        next();
    }
}

In claimsManager.js:

const checkForRequiredAuthContext = (req, res, next, authContextId) => {
    if (!req.authInfo['acrs'] || !req.authInfo['acrs'].includes(authContextId)) {
        if (isClientCapableOfClaimsChallenge(req.authInfo)) {
            
            const claimsChallenge = generateClaimsChallenge(authContextId);

            return res.status(claimsChallenge.statusCode)
                .set(claimsChallenge.headers[0], claimsChallenge.headers[1])
                .json({error: claimsChallenge.message});

        } else {
            return res.status(403).json({ error: 'Client is not capable' });
        }
    } else {
        next();
    }
}

const isClientCapableOfClaimsChallenge = (accessTokenClaims) => {
    if (accessTokenClaims['xms_cc'] && accessTokenClaims['xms_cc'].includes('CP1')) {
        return true;
    }

    return false;
}

Generating claims challenge

If there is an auth context entry in the database and the incoming request does not contain an access token with the necessary claims, the web API needs to create a claims challenge and send it to client application to allow the user to satisfy the challenge (for instance, perform multi-factor authentication). This is shown in claimsManager.js:

const generateClaimsChallenge = (authContextId) => {
    const clientId = process.env.CLIENT_ID;
    
    const statusCode = 401;
    
    // claims challenge object
    const challenge = { access_token: { acrs: { essential: true, value: authContextId }}};

    // base64 encode the challenge object
    const base64str = Buffer.from(JSON.stringify(challenge)).toString('base64');
    const headers = ["www-authenticate", "Bearer realm=\"\", authorization_uri=\"https://login.microsoftonline.com/common/oauth2/v2.0/authorize\", client_id=\"" + clientId + "\", error=\"insufficient_claims\", claims=\"" + base64str + "\", cc_type=\"authcontext\""];
    const message = "The presented access tokens had insufficient claims. Please request for claims designated in the www-authentication header and try again.";

    return {
        headers,
        statusCode,
        message
    }
}

Handling claims challenge

Once the client app receives the claims challenge, it needs to present the user with a prompt for satisfying the challenge via Azure AD authorization endpoint. To do so, we use MSAL's acquireTokenPopup() API and provide the claims challenge as a parameter in the token request. This is shown in fetch.js, where we handle the response from a HTTP POST request the to web API with the handleClaimsChallenge method:

export const postTask = async (task) => {
    const method = "POST"
    const accessToken = await getToken(protectedResources.apiTodoList.todoListEndpoint, protectedResources.apiTodoList.scopes, method);

    const headers = new Headers();
    const bearer = `Bearer ${accessToken}`;

    headers.append("Authorization", bearer);
    headers.append('Content-Type', 'application/json');

    const options = {
        method,
        headers: headers,
        body: JSON.stringify(task)
    };

    return fetch(protectedResources.apiTodoList.todoListEndpoint, options)
        .then((res) => handleResponse(res, protectedResources.apiTodoList.todoListEndpoint, options))
        .catch(error => console.log(error));
}

const handleResponse = async (response, endpoint, options, id = '') => {
    if (response.status === 200) {
        return response.json();
    } else if (response.status === 401) {
        if (response.headers.get('www-authenticate')) {
            return handleClaimsChallenge(response, endpoint, options, id);
        }

        throw new Error(`Unauthorized: ${response.status}`);
    } else {
        throw new Error(`Something went wrong with the request: ${response.status}`);
    }
}

const handleClaimsChallenge = async (response, endpoint, options, id = '') => {
    const account = msalInstance.getActiveAccount();

    const authenticateHeader = response.headers.get('www-authenticate');
    const claimsChallenge = parseChallenges(authenticateHeader);

    /**
     * Here we add the claims challenge to localStorage, using <cc.appId.userId.resource.method> scheme as key
     * This allows us to use the claim challenge string as a parameter in subsequent acquireTokenSilent calls
     * as MSAL will cache access tokens with different claims separately
     */
    addClaimsToStorage(
        `cc.${msalConfig.auth.clientId}.${account.idTokenClaims.oid}.${new URL(endpoint).hostname}.${options.method}`, 
        claimsChallenge.claims
    );

    try {
        const tokenResponse = await msalInstance.acquireTokenPopup({
            claims: window.atob(claimsChallenge.claims), // decode the base64 string
            scopes: protectedResources.apiTodoList.scopes,
            redirectUri: '/redirect.html',
        });

        if (tokenResponse.accessToken) {
            // call the API automatically with the new access token -this is purely for user experience.
            return callEndpoint(options, id);
        }

    } catch (error) {
        // catch if popups are blocked
        if (error instanceof BrowserAuthError &&
            (error.errorCode === "popup_window_error" || error.errorCode === "empty_window_error")) {

            const tokenResponse = await msalInstance.acquireTokenRedirect({
                claims: window.atob(claimsChallenge.claims),
                scopes: protectedResources.apiTodoList.scopes
            });

            if (tokenResponse.accessToken) {
                return callEndpoint(options, id);
            }

        }
    }
}

More information

• Developer's guide to Conditional Access authentication context
• Claims challenges, claims requests, and client capabilities
• Microsoft identity platform (Azure Active Directory for developers)
• Overview of Microsoft Authentication Library (MSAL)
• Quickstart: Register an application with the Microsoft identity platform (Preview)
• Quickstart: Configure a client application to access web APIs (Preview)
• Understanding Azure AD application consent experiences
• Understand user and admin consent
• Application and service principal objects in Azure Active Directory
• National Clouds
• MSAL code samples

For more information about how OAuth 2.0 protocols work in this scenario and other scenarios, see Authentication Scenarios for Azure AD.

Community Help and Support

Use Stack Overflow to get support from the community. Ask your questions on Stack Overflow first and browse existing issues to see if someone has asked your question before. Make sure that your questions or comments are tagged with [azure-active-directory react ms-identity adal msal].

If you find a bug in the sample, raise the issue on GitHub Issues.

To provide feedback on or suggest features for Azure Active Directory, visit User Voice page.

Contributing

If you'd like to contribute to this sample, see CONTRIBUTING.MD.

This project has adopted the Microsoft Open Source Code of Conduct. For more information, see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.