CVE-2024-1249: Keycloak OIDC Component Flaw Exposes Applications to High-Availability Attack via Unvalidated Cross-Origin Messages

A recently discovered vulnerability in Keycloak's OpenID Connect (OIDC) component has significant security implications. Known as CVE-2024-1249, this flaw exists in the "checkLoginIframe" [[1]] and enables attackers to send unvalidated cross-origin messages. Given the potential of this exploit to severely impact application availability, it is critical to understand the nature of the vulnerability and available security measures.

Exploit Details

The vulnerability is present in the "checkLoginIframe" function, part of Keycloak's OIDC component, which is designed to provide Single Sign-On (SSO) services. The purpose of this function is to handle authentication sessions for users, maintaining their logged-in state across multiple applications, and automatically logging them out when a session is terminated.

The vulnerability arises due to a lack of proper origin validation. The Keycloak application uses "postMessage" to send and receive messages from other windows and iframes within the same application. However, this function does not validate the origin of incoming messages, thereby permitting attackers to send malicious cross-origin messages without proper validation or restriction.

Code snippet showcasing the vulnerability

function checkLoginIframe() {
    var msg = '{"responseType":"callback", "callback":"check", "state":"' + state + '"}';
    ifr.contentWindow.postMessage(msg, clientOrigin);
}

As seen in the code snippet above, the "postMessage" function is being used to send a message to the iframe's contentWindow. However, there is no check in place to verify the origin of the incoming message, thus allowing malicious cross-origin messages to be sent and received.

Exploit Impact

The lack of proper origin validation creates the potential for attackers to exploit this vulnerability by sending a massive number of requests to the application in a short period. By doing so, they significantly impact the availability of the targeted service, leading to the widespread disruption of legitimate user access.

Original References

For more information on this vulnerability, please refer to the original report by Keycloak's security advisory:

- Keycloak OIDC Component Flaw (CVE-2024-1249)

Mitigation

To mitigate the impact of CVE-2024-1249, it is necessary to implement proper origin validation for incoming messages in the "checkLoginIframe" function. By restricting the reception of messages from unauthorized sources, it is possible to prevent attackers from taking advantage of this vulnerability.

Keycloak recommends updating to a fixed version of Keycloak to address this vulnerability

- Keycloak Fixed Versions: 12..4, 11..3, 13.., and later

Conclusion

In conclusion, the vulnerability CVE-2024-1249 in Keycloak's OIDC component highlights the critical importance of proper origin validation within applications. By addressing this vulnerability and implementing robust security measures, it is possible to reduce the risk of similar exploits in the future.

Timeline

Published on: 04/17/2024 14:15:08 UTC
Last modified on: 04/17/2024 16:15:07 UTC