Istio is an open platform designed to provide a secure and manageable connection between microservices. However, CVE-2022-23635, a newly discovered vulnerability in Istio, affects its control plane (istiod) and allows attackers to send specially crafted messages that can crash the control plane, consequently impacting the security and management of connected microservices. In this post, we'll dive deep into the details of this exploit, its potential impact, and possible mitigation strategies to protect your Istio deployments.

Exploit Details

The vulnerability in Istio's control plane exists due to a request processing error. Attackers can exploit this vulnerability by sending a precisely crafted message to an unprotected endpoint served over TLS port 15012. It's important to note that the attacker does not require authentication to exploit this vulnerability.

This link sheds more light on the original reference related to CVE-2022-23635.

To illustrate the vulnerability, let's consider the following code snippet

// istiod vulnerable code example
func onRequest(req *Request) error {
  // ...
  err := processMessage(req)
  if err != nil {
    return err
  }
  // ...
}

func processMessage(req *Request) error {
  // Vulnerability: The code does not validate the input properly,
  // which causes the control plane to crash when processing a malicious request
  // ...
}

Impact

For simple Istio installations, Istiod is usually reachable only from within the cluster, which limits the vulnerability's blast radius. However, in some deployment scenarios, particularly those involving multicluster topologies, Istiod's port 15012 can be exposed over the public internet, significantly increasing the potential for exploitation.

Mitigation Strategies

Currently, there are no effective workarounds for this vulnerability other than upgrading Istio to a version that addresses the issue. However, you can minimize the vulnerability's scope to some extent by limiting network access to Istiod as much as possible, thus reducing the number of potential clients that can exploit this vulnerability.

Here are a few suggestions

1. Update your Istio deployment to the latest version: Always ensure that you are running the most up-to-date version of Istio, as security fixes and enhancements are continually being added to new releases. You can check for updates and upgrade instructions on Istio's official documentation.

2. Limit access to Istiod's port 15012: Configure your network settings to restrict access to Istiod's port 15012, allowing only trusted clients to communicate with the control plane, especially in multicluster topologies.

3. Monitor your Istio environment: Regularly monitor your Istio deployments to detect any inconsistencies or potential attack attempts by setting up logging, metrics, and alerting so that you can respond promptly to potential security threats.

Conclusion

CVE-2022-23635 is a critical vulnerability that affects Istio's control plane, exposing it to potential attacks from malicious actors. Having discussed the nature of the exploit and its impact, we urge users to follow the recommended mitigation strategies and keep their Istio deployments up-to-date. By taking these steps, you can ensure a higher degree of security and robustness in your microservices environment.

Timeline

Published on: 02/22/2022 22:15:00 UTC
Last modified on: 03/01/2022 20:45:00 UTC