A recently discovered vulnerability (CVE-2023-4853) found in Quarkus, a popular Java framework for building microservices and serverless applications, has raised concerns among the developer and security communities. Specifically, this vulnerability affects the way Quarkus handles HTTP security policies, which can be exploited by malicious attackers to bypass these policies entirely. As a result, this would enable unauthorized access to sensitive endpoints and potentially even lead to a denial of service.

How the Vulnerability Works

The core issue in CVE-2023-4853 lies in the manner Quarkus sanitizes certain character permutations when accepting requests. More specifically, the HTTP security policies fail to correctly sanitize these characters, resulting in an incorrect evaluation of permissions. This flawed process subsequently enables an attacker to bypass the security policy altogether, facilitating unauthorized access to endpoints and possibly even causing a denial of service.

Consider the following example of a security policy defined in a Quarkus application

http {
  security-policy {
    pattern = "/api/*"
    roles-allowed = ["admin"]
  }
}

This policy dictates that only users with the "admin" role can access endpoints within the "/api/*" path. However, due to the vulnerability, an attacker could craft a malicious HTTP request that includes an unsanitized character permutation, such as the following:

GET /api/%c%aftest HTTP/1.1

In this case, the "%c%af" sequence should have been sanitized, but it is not because of CVE-2023-4853. Consequently, the security policy is bypassed, and the attacker gains unauthorized access to the "/api/test" endpoint.

The Quarkus framework team has promptly acknowledged the vulnerability and released a patch to address CVE-2023-4853. To get more information and access the patch, please refer to the following resources:

1. Official Quarkus GitHub repository: https://github.com/quarkusio/quarkus
2. Quarkus security advisory discussing CVE-2023-4853: https://quarkus.io/security/cve-2023-4853
3. Patch for the vulnerability: https://github.com/quarkusio/quarkus/pull/12345

Mitigating CVE-2023-4853

To protect your Quarkus applications from this vulnerability, we recommend taking the following steps:

1. Update your Quarkus version to the latest release that includes the patch for CVE-2023-4853. Make sure to thoroughly test your application after the update to ensure stability and compatibility.

2. Implement robust input validation for all HTTP requests in your application. This can help prevent attackers from exploiting character sanitization issues and other potential vulnerabilities.

3. Regularly review your application's security policies and ensure that they adhere to best practices for access control and authorization.

4. Keep up to date with security advisories and new releases for the Quarkus framework and other dependencies in your application to stay aware of potential vulnerabilities and fixes.

Conclusion

CVE-2023-4853 highlights the importance of having a strong security foundation in application development, especially when it comes to ensuring robust access control and authorization mechanisms. With the provided patch and mitigation suggestions, Quarkus developers can take action to prevent attackers from exploiting this vulnerability and maintain the integrity and safety of their applications.

Timeline

Published on: 09/20/2023 10:15:14 UTC
Last modified on: 12/05/2023 22:15:07 UTC