CVE-2023-29002: Cilium Debug Mode Vulnerability Exposes Sensitive Information

In today's security-conscious world, it's always important to stay on top of the latest vulnerabilities and their potential impacts on your systems. This post aims to raise awareness about a recently discovered vulnerability in Cilium, a widely used networking, observability, and a security solution with an eBPF-based dataplane.

Specifically, this vulnerability, designated as CVE-2023-29002, is centered around Cilium's behavior when run in debug mode. By logging sensitive information (such as TLS private keys), an attacker could potentially eavesdrop on or manipulate traffic between nodes within a cluster. Read on to learn more about the severity of this issue, as well as its mitigation and possible solutions.

Vulnerability Description

Cilium is designed to provide networking, observability, and security services in an eBPF-based dataplane. When run in debug mode, Cilium will log the contents of the cilium-secrets namespace, which could include sensitive data such as TLS private keys for Ingress and GatewayAPI resources.

An attacker who has access to the debug output of the Cilium containers could potentially use these details to intercept and modify traffic to and from the affected cluster. The exposure of this sensitive information can occur during Cilium agent restarts, right after the secrets within the namespace are modified, or upon the creation of new Ingress or GatewayAPI resources.

To better understand this issue, let's take a look at a sample code snippet that demonstrates how Cilium logs the cilium-secrets namespace when in debug mode:

package main

import (
	"fmt"
	"log"
	"os"

	"github.com/cilium/cilium/pkg/debug"
)

func main() {
	// Enable debug mode
	debug.Enable()

	// Get cilium-secrets
	secrets, err := GetCiliumSecrets()
	if err != nil {
		log.Fatalf("Failed to get cilium secrets: %v", err)
	}

	// Log sensitive information in debug output
	if debug.Enabled() {
		fmt.Printf("Cilium Secrets: %v\n", secrets)
	}

	// ...
}

func GetCiliumSecrets() (map[string]string, error) {
	// Dummy code to simulate fetching Cilium secrets
	secrets := map[string]string{
		"tls_key": "-----BEGIN RSA PRIVATE KEY-----...",
	}

	return secrets, nil
}

Mitigation

The developers of Cilium have addressed this vulnerability in the recent releases (1.11.16, 1.12.9, and 1.13.2). The recommended solution for affected users is to upgrade to one of these fixed versions immediately.

For users who are unable to upgrade, a temporary workaround is to disable debug mode in Cilium. This will prevent the logging of sensitive data within the cilium-secrets namespace, thus reducing the risk of information disclosure and data manipulation.

You can find more details about this vulnerability from the following sources

- Cilium GitHub Repository: https://github.com/cilium/cilium
- Cilium Security Advisory: https://cilium.io/security-advisory/cve-2023-29002

Conclusion

CVE-2023-29002 exposes a serious vulnerability in Cilium that could potentially enable attackers to view and manipulate traffic within affected clusters. It's essential for users to upgrade to the latest fixed versions or to disable debug mode in Cilium as soon as possible to mitigate this risk. Stay vigilant, and always prioritize the security of your systems.

Timeline

Published on: 04/18/2023 22:15:00 UTC
Last modified on: 05/04/2023 13:01:00 UTC