HashiCorp Nomad has become one of the popular tools for container orchestration, enabling developers to distribute and manage applications across various environments. However, with great power comes great responsibility. A recent vulnerability in Nomad versions 1.4. to 1.4.1 has been identified as CVE-2022-3867, which affects event stream subscribers using a token with Time-To-Live (TTL). The vulnerability has been fixed in version 1.4.2. In this post, we'll dissect this security issue and provide insights into its exploitation and how to mitigate its impact.

CVE-2022-3867: The Issue

In Nomad versions 1.4. to 1.4.1, event stream subscribers that use a token with TTL continue to receive updates even after the token has expired, until the token garbage is collected. This poses a security concern as unauthorized users can gain access to sensitive or confidential information beyond their allowed TTL. Let's take a closer look at this vulnerability with an example.

Example Code Snippet with Vulnerability

package main

import (
	"fmt"
	"time"

	"github.com/hashicorp/nomad/api"
)

func main() {
	// Create a new Nomad client
	client, _ := api.NewClient(api.DefaultConfig())

	// Create a new token with TTL
	createdToken, _, _ := client.ACLTokens().Create(&api.ACLToken{
		Name:      "Test Token",
		Type:      "client",
		Policies:  []string{"readonly"},
		Global:    true,
		ExpiresAt: time.Now().Add(10 * time.Minute),
	}, nil)

	// Subscribe to the event stream
	updates, _, _ := client.Event().Stream(api.QueryOptions{Token: createdToken.SecretID})

	for {
		select {
		case update := <-updates:
			fmt.Printf("Update: %v\n", update)
		}
	}
}

In this code snippet, we create a new Nomad client, create a token with a 10-minute TTL, and subscribe to the event stream. The updates channel will continue to receive updates even after the token has expired.

Exploitation Details

An attacker who manages to gain access to an expired token can exploit this vulnerability by continuing to listen to the event stream and gain unauthorized information beyond the token's allowed TTL. This can lead to potential information leakage or unauthorized changes in the system depending on the permissions granted to the token.

Mitigation: Upgrading to Nomad 1.4.2

The vulnerability has been fixed in Nomad version 1.4.2. Users are strongly advised to upgrade to the latest version to prevent any exploitation of this vulnerability. You can find the release notes and download links here:

- Nomad 1.4.2 Release Notes
- Nomad 1.4.2 Download Page

After upgrading to Nomad 1.4.2, the tokens with TTL will no longer receive updates from the event stream after their expiration, ensuring a more secure and controlled environment.

Conclusion

The CVE-2022-3867 vulnerability in HashiCorp Nomad and Nomad Enterprise 1.4. to 1.4.1 demonstrates the importance of staying updated on security issues and patching them immediately. As an open-source project, the collaboration between the community and the project maintainers plays a significant role in identifying and fixing vulnerabilities like this one. By upgrading to Nomad 1.4.2, users can safeguard their systems from potential attackers and ensure the security and integrity of their applications and infrastructure.

Timeline

Published on: 11/10/2022 06:15:00 UTC
Last modified on: 11/15/2022 17:24:00 UTC