Securing AJAX requests against Cross-Site Request Forgery (CSRF) attacks is crucial for the safety of your Spring Security-enabled REST APIs. CSRF protection in Spring Security involves generating and validating tokens to ensure that the requests originate from the expected source. Below is a guide on how to implement CSRF protection for AJAX requests in Spring Security for REST APIs:

Step 1: Include CSRF Token in Response

In your server-side code, include the CSRF token in the response. This token can be obtained from Spring Security's CsrfToken class.

                
    @RestController
    public class CsrfController {

        @GetMapping("/csrf-token")
        public CsrfToken getCsrfToken(HttpServletRequest request) {
            return (CsrfToken) request.getAttribute(CsrfToken.class.getName());
        }
    }
                
            

Step 2: Retrieve CSRF Token on the Client Side

In your AJAX request, retrieve the CSRF token from the server and include it in the headers of subsequent requests.

                
    // Fetch CSRF token from the server
    fetch('/csrf-token')
        .then(response => response.json())
        .then(csrfToken => {
            // Include the CSRF token in the headers of AJAX requests
            const headers = new Headers();
            headers.append('X-CSRF-TOKEN', csrfToken.token);

            // Make AJAX request with the CSRF token in the headers
            fetch('/api/your-endpoint', {
                method: 'POST',
                headers: headers,
                body: JSON.stringify(yourData)
            })
            .then(response => response.json())
            .then(data => console.log(data))
            .catch(error => console.error('Error:', error));
        });
                
            

Step 3: Configure CSRF Protection in Spring Security

In your Spring Security configuration, ensure that CSRF protection is enabled.

                
    @Configuration
    @EnableWebSecurity
    public class SecurityConfig extends WebSecurityConfigurerAdapter {

        @Override
        protected void configure(HttpSecurity http) throws Exception {
            http
                .csrf().csrfTokenRepository(CookieCsrfTokenRepository.withHttpOnlyFalse())
                .and()
                // ... other configurations
        }
    }
                
            

In this example, CookieCsrfTokenRepository.withHttpOnlyFalse() is used to store the CSRF token in a cookie. Adjust this configuration based on your specific requirements.

Step 4: Test Your AJAX Requests

Ensure that your AJAX requests include the CSRF token in the headers, and the CSRF token is validated on the server-side. This helps protect your REST APIs against CSRF attacks.

Note:

• Customize the CSRF token handling based on your application's needs.
• Ensure that the CSRF token is correctly included in the headers of AJAX requests.
• Always validate the CSRF token on the server-side.

This example provides a basic setup for implementing CSRF protection for AJAX requests in Spring Security for REST APIs. Adjustments may be needed based on your specific use case and security requirements.