How do you handle CSRF protection in Spring Security?

Table of Contents

Introduction

Cross-Site Request Forgery (CSRF) is a type of attack where malicious websites can trick a user’s browser into making unwanted requests to a different site where the user is authenticated. This can lead to security breaches, like transferring money or changing account settings, without the user's knowledge.

Spring Security provides built-in support to protect against CSRF attacks. This is typically done by generating a CSRF token that is included in every state-changing HTTP request (like POST, PUT, DELETE) sent by the client. The server then validates this token to ensure that the request is legitimate and originates from the authenticated user.

In this article, we'll explore how to handle CSRF protection in Spring Security, from enabling to disabling it, and how to customize the CSRF configuration based on your application's requirements.

1. Enabling CSRF Protection in Spring Security

By default, Spring Security enables CSRF protection in most web applications. The CSRF token is automatically included in forms (via hidden fields) and is validated on the server side for each state-changing request.

If you're using Spring Boot, CSRF protection is typically enabled out-of-the-box in the default configuration. However, you can explicitly enable it and configure its behavior through Spring Security's Java-based configuration.

Example: Enabling CSRF Protection

In this example, **http.csrf().enable()** explicitly enables CSRF protection (although it is enabled by default).

2. How CSRF Protection Works in Spring Security

When CSRF protection is enabled, Spring Security generates a CSRF token that must be included in every state-changing HTTP request (POST, PUT, DELETE, etc.). This token is sent along with the request and compared with the token stored in the user’s session.

• Form-based requests: When using Spring Forms (e.g., @FormTag), the CSRF token is automatically added as a hidden form field.

• Ajax-based requests: For AJAX requests, you can manually include the CSRF token in the request header.

3. Customizing CSRF Protection

Spring Security allows you to configure the behavior of CSRF protection to fit the needs of your application.

1. Custom CSRF Token Repository

By default, Spring Security uses an in-memory repository for storing CSRF tokens. However, you can customize this to store tokens elsewhere, such as in a database or Redis.

In this example, the CSRF token is stored in a cookie (with HTTPOnly set to false, making it accessible to JavaScript). You can also configure other types of repositories, such as custom **JwtCsrfTokenRepository** or **RedisCsrfTokenRepository**.

2. Excluding Specific Endpoints from CSRF Protection

Sometimes, certain endpoints (e.g., for API calls or third-party integrations) don't require CSRF protection. You can disable CSRF for specific URLs while keeping it enabled for others.

In this configuration, CSRF protection is disabled for any URL that matches /api/**, but it is still applied to other endpoints.

3. Changing CSRF Token Parameter Name

By default, the CSRF token is expected to be in a request parameter called _csrf. If you want to change this parameter name, you can configure the CSRF protection to use a custom parameter.

4. Disabling CSRF Protection (Not Recommended)

While it is generally advised to keep CSRF protection enabled to ensure the security of your application, there are scenarios where you may need to disable CSRF protection, especially in stateless applications (like those using JWT tokens for authentication), or when handling non-browser clients (e.g., mobile apps or API-based services).

Example: Disabling CSRF Protection

However, disabling CSRF protection in a traditional web application (where sessions and cookies are used) is not recommended because it opens the application to CSRF attacks.

5. Testing CSRF Protection

To verify that CSRF protection is working properly, you can:

1. Attempt a POST request to a protected URL without including the CSRF token. You should get a 403 Forbidden error.
2. Send the correct CSRF token in the request, either through the form or the HTTP header, and the request should be successfully processed.

Spring Security provides a number of tools to log CSRF protection events, allowing you to debug or trace invalid CSRF attempts.

Conclusion

CSRF protection is essential for defending your Spring applications against malicious attacks where unauthorized requests are made on behalf of an authenticated user. Spring Security provides robust, out-of-the-box support for CSRF tokens and makes it easy to enable, customize, or disable CSRF protection based on your application's needs.

• Enabling CSRF is straightforward and often enabled by default.
• Customizing CSRF allows you to change the token repository, exclude certain URLs, or even change the parameter name.
• Disabling CSRF should only be done in specific cases, such as API-driven or stateless applications.

By configuring CSRF protection correctly, you can safeguard your application from this common web security vulnerability and ensure your users' data remains safe.