A newly discovered vulnerability in Keycloak, a widely-used open-source identity and access solution, exposes a Cross-site Scripting (XSS) vulnerability under certain conditions. This vulnerability, identified as CVE-2022-1438, allows attackers to exploit this weakness by injecting malicious JavaScript code while impersonating a user, leading to potential exploit scenarios such as data theft, account takeover, or other security breaches.

In this post, we will analyze the details of CVE-2022-1438, including the vulnerable code, steps to reproduce the vulnerability, mitigation steps, and useful links to original references and exploit details.

Code Snippet

The vulnerable code stems from Keycloak's handling of HTML entities during user impersonation. When an attacker attempts to impersonate a user, the system erroneously does not sanitize special HTML characters such as <, >, and &, thus allowing the embedded JavaScript code to be executed in the user's browser.

Consider the following example

// Attacker-controlled username with malicious payload
const username = "<script>alert('XSS');</script>";

// In Keycloak, impersonating a user without proper sanitization
keycloak.impersonate(username);

The malicious JavaScript payload in the example above would then be executed when an impersonation is made, rendering the user's environment vulnerable to attacks.

Exploit Details

To exploit this vulnerability, an attacker must have access to Keycloak's user impersonation feature. This typically requires elevated privileges like administrative access, but it could also result from misconfigurations that inadvertently grant this capability to lower-privileged users.

Once the impersonation access is secured, the attacker can then craft a malicious username containing a JavaScript payload, as shown earlier in the code snippet. With this username, the attacker can now effectively use the user impersonation feature to target users and execute arbitrary JavaScript code within their browser, leading to potential security threats.

Mitigation

To mitigate this vulnerability, it's crucial to apply vendor-supplied patches that address the flawed processing of HTML entities. Keycloak has already released a patch to fix this issue, which can be found on their official GitHub repository.

Furthermore, it's essential to review and enforce proper access controls for Keycloak's user impersonation feature. By restricting access to only authorized individuals or accounts, the risk of exploitation can be significantly reduced.

Original References

The vulnerability was initially reported through the Keycloak project, and further details can be found in the following locations:

- Keycloak - CVE-2022-1438 Advisory
- CVE Details - CVE-2022-1438
- National Vulnerability Database (NVD) - CVE-2022-1438

Conclusion

CVE-2022-1438 highlights the importance of proper input validation and sanitization as key components in developing secure applications. Users of Keycloak should patch their systems immediately and verify that access controls for privileged features are correctly enforced. Staying up-to-date with vendor-supplied patches and maintaining strong security practices will help to prevent exploitation and keep your environment safe.

Timeline

Published on: 09/20/2023 14:15:00 UTC
Last modified on: 09/25/2023 13:40:00 UTC