Securing API Access to SharePoint Online: A Guide to Azure Application Registration and SharePoint App Creation

Gaining API access to a SharePoint environment is essential for developers looking to build applications that interact with SharePoint data. This can be achieved in two primary ways: through Azure Application registration or by creating an application directly in SharePoint. Each method has its own set of steps and considerations. In this blog, we will explore both methods and guide you through the process of setting up and securing API access to your SharePoint environment.

Method 1: Azure Application Registration

Azure Active Directory (Azure AD) offers a secure way for applications to access SharePoint through Azure Application registration. Here's how you can set it up:

1. Navigate to Azure Portal: Start by going to the Azure portal and creating a new application registration. This will represent your application in the directory and will be the basis for its authentication and authorization processes.

2. Configure Application Settings: Assign a name to your application and configure settings such as supported account types and redirect URIs. These settings will determine how your application interacts with users and other services.

3. Set API Permissions: The most crucial step is setting the API permissions for your application. Navigate to the "API permissions" section and add permissions for SharePoint. For read-only access, you will typically add permissions such as Sites.Read.All or Files.Read.All. Ensure you understand the scope and implications of each permission you grant.

Method 2: Creating an Application in SharePoint

For those who prefer to work directly within the SharePoint environment, creating an application in SharePoint is a viable alternative. Here's how to do it:

1. Access SharePoint Admin Center: Log into your SharePoint admin center and navigate to the 'appregnew.aspx' page (https://<main-site name>.sharepoint.com/_layouts/15/appregnew.aspx ). This is where you'll register your new application. This is needed only if the Azure AD APPlication is not created.

1. Generate Client ID & Secret: Click on the "Generate" button to create a new client ID and secret. These credentials will be used to authenticate your application with SharePoint.

Once the Application is created through Method 1 or Method 2 next step is to provide right access to the same. 

Next step is granting permissions to the newly created principal. Since we're granting tenant scoped permissions this granting can only be done via the appinv.aspx page on the tenant administration site. You can reach this site via https://sitename-admin.sharepoint.com/_layouts/15/appinv.aspx. 

Once the page is loaded add your client id and look up the created principal:

Set Permissions: Define the permissions your application will need by providing the permission XML. For full control permissions, you might use something like:

<AppPermissionRequests AllowAppOnlyPolicy="true"> <AppPermissionRequest Scope="http://sharepoint/content/tenant" Right="FullControl" /> </AppPermissionRequests>

When you click on Create you'll be presented with a permission consent dialog. Press Trust It to grant the permissions:

Best Practices and Considerations

• Security: Regardless of the method you choose, security should be your top priority. Treat your client ID and secret as you would any sensitive credentials. Ensure that only authorized personnel have access to this information and that it's stored securely.

• Permission Scope: Always adhere to the principle of least privilege. Grant only the permissions necessary for your application to function. Excessive permissions can pose a security risk.

• Maintenance: Regularly review and update your application's settings and permissions to accommodate changes in your environment or application requirements.

• Documentation: Both Microsoft's Azure documentation and SharePoint documentation are excellent resources. Refer to these regularly to stay updated on best practices and new features.

By following these steps and considerations, you can successfully set up API access to your SharePoint environment, whether through Azure Application registration or directly within SharePoint. Each method has its own benefits and the best choice depends on your specific needs and environment. Always prioritize security and stay informed on best practices to ensure a successful and safe integration.