CVE-2022-31733 - Exploiting Diego Release and CF Deployment Vulnerabilities in Cloud Foundry Application Access via Unprotected Routes

In this long read, we will take a deep dive into a vulnerability identified in Cloud Foundry's Diego Release (versions 2.55. to 2.69.) and CF Deployment (versions 17.1 to 23.2.). The security flaw, known as CVE-2022-31733, reveals how an attacker can exploit an unprotected route and access applications within a Cloud Foundry environment without presenting a valid client certificate. We'll explore the details of the vulnerability, how to exploit it, review a code snippet, and discuss mitigation measures for affected Cloud Foundry users.

Vulnerability Details

Starting with Diego Release 2.55. up to 2.69. and CF Deployment 17.1 up to 23.2., there exists an issue in which applications are accessible via another port on Diego cells that isn't secured properly. As a result, application ingress can occur without a valid client certificate. This vulnerability can be exploited when mTLS (Mutual Transport Layer Security) route integrity is enabled and unproxied ports are turned off.

Upon further inspection, it appears that an attacker can potentially connect to an application that should only be reachable via mTLS without having to present a client certificate. This security flaw essentially bypasses the authentication mechanism in place to protect these applications.

Exploit

In order to exploit this vulnerability, the attacker would need to identify the open port on the Diego cell through a port scanning tool or by examining network traffic. Once the open port is discovered, the attacker can attempt to connect to the application without presenting a valid client certificate.

Here is a simple code snippet to demonstrate how an attacker might exploit this vulnerability using Python and the requests library:

import requests

base_url = 'https://target-cf-example.com';
vulnerable_port = 12345

response = requests.get(f'{base_url}:{vulnerable_port}')

if response.status_code == 200:
    print('Successfully accessed the target application without a client certificate!')
else:
    print('Failed to access the target application.')

Original References

This vulnerability was first disclosed on Cloud Foundry's Github repository, filed under issue #CVE-2022-31733. You can find more information about the issue here (https://github.com/cloudfoundry/cf-deployment/issues/CVE-2022-31733).

Cloud Foundry has also published the full details about this security vulnerability, which can be accessed at the following link: https://www.cloudfoundry.org/blog/cve-2022-31733/

Mitigation Measures

In order to address the vulnerability, Cloud Foundry has released Diego Release 2.70. and CF Deployment 23.3.. It is strongly recommended for all affected users to update their deployment to the latest version as soon as possible.

If updating is not possible, users can also implement network security measures to limit access to the discovered open ports, or disable the corresponding feature and utilize alternative application access methods. However, these methods are not foolproof, and it is best to upgrade to the patched version as soon as feasible.

Conclusion

CVE-2022-31733 exposes a significant vulnerability within several versions of Cloud Foundry's Diego Release and CF Deployment. By exploiting this weakness, an attacker can potentially access applications that should be protected by mTLS without providing a valid client certificate. It is crucial for Cloud Foundry users affected by this vulnerability to update their deployments to the latest version or apply necessary security measures to contain and mitigate potential threats.

Timeline

Published on: 02/03/2023 19:15:00 UTC
Last modified on: 02/10/2023 17:37:00 UTC