CVE-2023-24488 - Cross-site scripting vulnerability in Citrix ADC and Citrix Gateway: How it works and what you need to know!

Citrix is a popular solution for application delivery, load balancing, and secure remote access. Two major components of the Citrix ecosystem are the Citrix ADC (Application Delivery Controller) and Citrix Gateway. Unfortunately, a new vulnerability (CVE-2023-24488) has been discovered that allows an attacker to perform a cross-site scripting (XSS) attack. In this post, we'll dive into the details of the vulnerability, explain how it can be exploited, and point you towards references and resources to help you understand and mitigate this issue.

The Vulnerability

CVE-2023-24488 revolves around a cross-site scripting vulnerability in Citrix ADC and Citrix Gateway. A cross-site scripting vulnerability occurs when an attacker is able to inject malicious code, usually JavaScript, into a victim's browser through a vulnerable application. This can lead to a range of malicious outcomes, like stealing sensitive information or gaining control of the victim's account.

In the case of CVE-2023-24488, the vulnerability exists due to insufficient input validation in certain components of Citrix ADC and Citrix Gateway. As a result, an attacker can craft a malicious URL containing the XSS payload, which, when clicked on by the unsuspecting user, triggers the XSS attack.

For a better understanding, let's take a look at a sample exploit code snippet for CVE-2023-24488

<a href="https://vulnerable-citrix.example.com/login.jsp?parameter=<script>/*malicious_code_here*/</script>">;
  Click here to login to Citrix
</a>

In this example, <script>/*malicious_code_here*/</script> represents the actual malicious JavaScript code that an attacker might use. When the user clicks the seemingly harmless "Click here to login to Citrix" link, the malicious code executes in their browser, enabling the attacker to carry out their desired action (e.g., stealing session cookies, redirecting to a malicious site, etc.).

Original References

The Citrix Security Bulletin for this vulnerability (CTX276688) can be found here: https://support.citrix.com/article/CTX276688

This bulletin provides a thorough overview of the vulnerability, affected products and versions, and recommended mitigation steps. The Common Vulnerabilities and Exposures (CVE) entry for this issue (CVE-2023-24488) can be found here: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-24488

Mitigation Measures

The most effective way to address this vulnerability is to apply the appropriate security updates provided by Citrix. You can find the relevant updates and detailed instructions in the Citrix Security Bulletin: https://support.citrix.com/article/CTX276688

In addition to applying the security patches, it's always a good practice to follow these general security guidelines to protect against XSS attacks:

1. Implement Content Security Policy (CSP) headers on your web applications to restrict the execution of external scripts.
2. Implement strong input validation and output encoding mechanisms to ensure user input is sanitized before rendering.
3. Educate your users on the risks of clicking untrusted links and the importance of verifying the URL before clicking on it.

Conclusion

CVE-2023-24488 is a serious cross-site scripting vulnerability in Citrix ADC and Citrix Gateway that could have potentially devastating consequences if exploited. It's important to stay informed about the latest security threats, apply the necessary patches, and implement good security practices to minimize the risk of falling victim to such attacks. Stay safe out there!

Timeline

Published on: 07/10/2023 21:15:00 UTC
Last modified on: 07/11/2023 13:28:00 UTC