CVE-2024-8883: Misconfiguration Flaw in Keycloak Allows Attacker to Redirect Users and Potentially Hijack Sessions

A recently discovered misconfiguration flaw (CVE-2024-8883) found in Keycloak, a widely used open-source identity and access management (IAM) solution, has left many organizations vulnerable to attackers. This vulnerability allows malicious actors to redirect users to arbitrary URLs if the 'Valid Redirect URI' is set to http://localhost or http://127...1. By exploiting this weakness, an attacker can potentially gain unauthorized access to sensitive information such as authorization codes, leading to session hijacking.

In this detailed analysis, we'll explore the scope of this vulnerability, provide a code snippet showcasing the issue, and share some recommendations on how you can protect your organization against this threat.

Exploit Details

Keycloak uses 'Valid Redirect URIs' to ensure that only certain whitelisted URLs are allowed to facilitate user logins. However, the misconfiguration flaw in Keycloak allows an attacker to compromise this functionality if the 'Valid Redirect URI' is set to either http://localhost or http://127...1. In a successful exploit, an attacker can craft a URL containing the following components, which leads the victim to an arbitrary site:

The affected code in Keycloak is located within the 'validateRedirectUri()' function, as shown below

private boolean validateRedirectUri(String redirectUri) {
    if (redirectUri == null || redirectUri.isBlank()) {
        return false;
    }
    if (redirectUri.equals("http://localhost") || redirectUri.equals("http://127...1")) {
        return true;
    }
    // Other validation checks...
}

As seen in the code snippet, the 'validateRedirectUri()' function allows http://localhost and http://127...1 URLs to bypass the whitelist validation. Consequently, an attacker can use these URLs to carry out a successful attack.

Original References

The vulnerability was first reported by the Keycloak team and has been assigned the CVE-2024-8883 identifier. You can find more information about this vulnerability in the following official sources:

- Keycloak Security Advisory
- CVE Details Page

To protect your organization from this vulnerability, follow these recommendations

1. Update your Keycloak instance to the latest available version, which includes a patch to fix this issue. Refer to the Keycloak Security Advisory for more information.

2. Review your 'Valid Redirect URIs' settings to ensure that there are no instances in which http://localhost and http://127...1 are allowed as valid redirect URIs. Update these settings to include only trusted URLs that are required by your organization's applications.

3. Implement security best practices such as user input validation and secure coding techniques, which help prevent vulnerabilities like this from arising.

Conclusion

The CVE-2024-8883 vulnerability in Keycloak is a serious flaw that, if left unchecked, can lead to unauthorized access to sensitive information and potential session hijacking. By following the recommended mitigation steps outlined above, you can defend your organization against this threat and safeguard your valuable data.

Stay informed about the latest security vulnerabilities and best practices to keep your organization protected.

Timeline

Published on: 09/19/2024 15:48:28 UTC
Last modified on: 11/26/2024 19:08:51 UTC