Posted in AZ-500 Azure Security Engineer Associate, Azure Administrator, Azure Security Engineer, Azure Solutions Architect, MS Cyber Security Architect Expert

Entra Application Registration

   October 31, 2024

Entra Application Registration in Microsoft Entra ID (formerly Azure Active Directory) is essential for allowing applications to authenticate and integrate with Microsoft Entra services, enabling secure access to resources. Let’s break down the core concepts, functions, features, configuration, management, monitoring, and usage of Entra Application Registration with examples for a comprehensive understanding.

1. Core Concepts in Entra Application Registration

Application Registration
This process creates a unique application identity within Entra ID, which allows the application to securely access Microsoft APIs and other resources on behalf of users or the application itself. Each application registration includes details about the app, such as its client ID, redirect URIs, and permission scopes.

Application Object vs. Service Principal

  • Application Object: The application object is the global definition of the application in Entra ID and represents the application’s identity, configuration, and metadata.
  • Service Principal: A service principal is a local instance of an application object that enables the app to access resources within a specific tenant. This is especially relevant when the app needs permissions in multiple Entra tenants.

Client ID and Client Secret

  • Client ID: A unique identifier for your application, automatically generated during registration.
  • Client Secret: A password-like credential used by the application to authenticate itself when accessing APIs.

Redirect URI
The redirect URI (or callback URL) is where the application receives the authentication response after a user or app is authenticated.

Permissions and Scopes
Permissions determine what data or resources the application can access. They are divided into:

  • Delegated Permissions: Access data on behalf of a signed-in user.
  • Application Permissions: Allow the application to access data without a signed-in user.

2. Key Functions and Features of Entra Application Registration

Authentication
Entra Application Registration enables an app to authenticate users securely using various protocols, like OpenID Connect and OAuth 2.0, enabling single sign-on (SSO) and secure access to Microsoft 365 or custom applications.

Authorization and Access Control
Through permissions, the app can request access to resources with various levels of granularity. Administrators can control which permissions the app can request and ensure that access is approved before the app can perform specific actions.

Single Sign-On (SSO)
With SSO, registered applications can enable users to sign in once and gain access to multiple resources or applications without needing to re-enter their credentials.

API Integration and Microsoft Graph Access
Applications can request access to Microsoft Graph, which provides access to Microsoft 365 data, including users, groups, and email.

Multi-Tenant Applications
By registering an app as multi-tenant, it can be used by users from other Entra tenants, making it ideal for SaaS (Software as a Service) applications.

Certificates and Secrets
Application registration allows for secure app authentication using either client secrets or certificates. Certificates are more secure and are recommended for production environments.

3. Configuration and Management of Entra Application Registration

Step-by-Step Configuration:

Step 1: Register a New Application

  1. In the Microsoft Entra admin center, go to App registrations > + New registration.
  2. Enter the application’s Name.
  3. Select the Supported account types:
  • Single tenant: Only available in your organization.
  • Multi-tenant: Available to any organization.
  • Multi-tenant + personal accounts: Allows Microsoft accounts to access as well.
  1. Specify a Redirect URI if needed (e.g., for web or mobile apps).
  2. Click Register to create the application.

Step 2: Configure Authentication

  1. Go to the Authentication tab.
  2. Add a Platform (Web, Mobile, or Desktop) and specify redirect URIs for each platform.
  3. Enable features like ID tokens (for OpenID Connect) if required.

Step 3: Set Permissions

  1. Under the API Permissions tab, add necessary permissions for the application.
  • For Microsoft Graph or other APIs, select permissions such as User.Read for basic profile access.
  1. Choose between Delegated or Application permissions based on the app’s requirements.

Step 4: Add Certificates and Secrets

  1. Go to the Certificates & secrets tab.
  2. Add a Client Secret or upload a Certificate for secure app authentication.
  3. Save the secret value immediately as it won’t be displayed again.

Step 5: Branding and Properties (Optional)

  1. Go to the Branding & properties tab.
  2. Customize app branding, including logo, publisher, and terms of service URL.
  3. Branding enhances the user experience during the sign-in process.

Step 6: Create a Service Principal (for Multi-Tenant Applications)
Once registered, a service principal is automatically created for single-tenant applications within the same tenant. For multi-tenant apps, a service principal will be created in each tenant that consents to the app.

4. Usage and Working Examples

Example 1: Web Application Using Microsoft SSO

  1. Register App: Create a new app registration for a web app, specify a redirect URI (https://myapp.com/auth), and enable ID tokens for OpenID Connect authentication.
  2. Permissions: Assign User.Read permission to allow the app to fetch basic profile data.
  3. Client ID and Secret: Use the client ID and client secret to configure the app’s authentication flow.
  4. Implementation: Use Microsoft Authentication Library (MSAL) to implement sign-in and request profile data from Microsoft Graph.
  5. User Authentication: When users visit the app, they are redirected to Microsoft’s login page, authenticate, and are redirected back to https://myapp.com/auth.

Example 2: Service Application Accessing Microsoft Graph

  1. Register App: Register the app as a single-tenant service application with no redirect URI.
  2. Permissions: Add Application Permissions for User.Read.All to allow the app to access all users’ information.
  3. Client ID and Certificate: Configure the app to use a certificate for secure access.
  4. Implementation: Write a script using Microsoft Graph SDK, authenticating with the client ID and certificate to fetch user data.
  5. Execution: The app can now run as a background service, querying Microsoft Graph for user data securely without requiring user sign-in.

5. Monitoring and Management of Entra Application Registration

Monitoring Application Sign-ins

  1. In the Entra admin center, go to Monitoring > Sign-ins.
  2. Filter by Application to see authentication requests, including successes, failures, and user details.

Conditional Access Policies

  1. Configure Conditional Access to control access to the application based on factors like device compliance, location, or risk level.
  2. For example, enforce multi-factor authentication (MFA) for specific apps for higher security.

Audit Logs

  1. Go to Audit logs in the Entra portal to track changes to app configurations, permissions, and assignments.
  2. Logs help identify changes over time, useful for compliance and troubleshooting.

Token Lifetime and Session Management

  1. Set custom token lifetimes in Token configurations to control how long tokens are valid, balancing security and usability.
  2. Manage session persistence to keep users logged in or require re-authentication based on security needs.

6. Best Practices for Entra Application Registration

  • Use Certificates Over Secrets: Certificates are more secure than client secrets, especially for production applications.
  • Regularly Review Permissions: Limit permissions to the minimum required and review them periodically to prevent excessive access.
  • Enable Conditional Access for Security: Apply conditional access policies to add layers of security for sensitive applications.
  • Monitor Sign-Ins and Audit Logs: Regularly review sign-in and audit logs to detect unauthorized access or misconfigurations.
  • Rotate Secrets Periodically: If using client secrets, rotate them regularly to reduce risk of credential compromise.
  • Use Application Roles and Scopes: Define application roles and scopes for granular access control, especially for multi-tenant applications.

Summary

Entra Application Registration provides a structured, secure method for integrating applications with Microsoft Entra ID. Through this process, apps can authenticate users, access Microsoft APIs, and integrate with various services securely. From configuring authentication and permissions to monitoring activity, it enables a seamless experience for app developers while maintaining a high level of security and compliance for organizations.

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Author: tonyhughes