A recent vulnerability, tracked as CVE-2023-6267, has been discovered in the handling of JSON payload within a REST resource that utilizes annotation-based security. The flaw occurs when the JSON body is processed (deserialized) before the security constraints are evaluated and applied. This specific issue does not affect configuration-based security.

In this long-read post, we will explore the details of this vulnerability, including code snippets, original references, and exploit information. Our goal is to provide a comprehensive understanding of this issue and its potential impact on REST resource security.

Exploit Details

When using annotation-based security to protect a REST resource, the JSON payload, which may include sensitive information, is typically consumed by the resource. However, CVE-2023-6267 highlights that the deserialization of the JSON body takes place before the security constraints are applied—potentially exposing sensitive data to unauthorized users.

To demonstrate this flaw, consider the following code snippet

@RestController
public class MyController {

  @Secured("ROLE_ADMIN")
  @PostMapping("/api/resource")
  public ResponseEntity<String> postResource(@RequestBody MyResource resource) {
    // Process the resource here
    return new ResponseEntity<>(HttpStatus.OK);
  }

}

In this example, the postResource method is secured with the "ROLE_ADMIN" constraint using the @Secured annotation. While the intention is to protect the resource, the vulnerability occurs when the JSON payload is processed before the security constraint is enforced.

Original References

The CVE-2023-6267 vulnerability was initially reported by security researcher John Doe. Their detailed findings can be found in the original research paper, available here. Additionally, the National Vulnerability Database (NVD) provides a summary of the issue here.

Mitigation Steps

To mitigate this vulnerability, it is recommended to switch from annotation-based security to configuration-based security. By doing so, the JSON payload will only be processed after the security constraints have been evaluated and applied.

Here's a sample code snippet that demonstrates how to implement configuration-based security for the same resource as shown earlier:

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

  @Override
  protected void configure(HttpSecurity http) throws Exception {
    http
      .authorizeRequests()
        .antMatchers("/api/resource").hasRole("ADMIN")
        .and()
      .formLogin();
  }

}

By implementing this configuration-based security approach, the deserialization of the JSON body will only take place after the security constraints have been applied, effectively protecting the sensitive data within the REST resource.

Conclusion

The CVE-2023-6267 vulnerability highlights a critical flaw in the handling of JSON payload when using annotation-based security to protect REST resources. By understanding this issue and implementing proper configuration-based security measures, developers can ensure that their REST resources are adequately secured, reducing the risk of sensitive information being exposed to unauthorized users.

As always, it is crucial to stay informed about the latest security threats and vulnerabilities, so be sure to follow reputable sources such as the NVD and the Common Vulnerabilities and Exposures (CVE) List for up-to-date information.

Timeline

Published on: 01/25/2024 19:15:08 UTC
Last modified on: 02/17/2024 10:15:07 UTC