CVE-2024-26481 - Reflection XSS Vulnerability Discovered in Kirby CMS v4.1.: Exploiting and Mitigating the Issue

A significant security issue, identified as CVE-2024-26481, was recently discovered in Kirby CMS v4.1.. This vulnerability involves a reflected self-XSS (cross-site scripting) attack, which could potentially lead to unauthorized information disclosure and even account compromise if exploited. In this post, we will delve into the technical details behind this vulnerability, demonstrate relevant code snippets, and provide guidance on how to mitigate the issue. We will also include links to original references detailing the recent discovery.

Background

Kirby CMS is a popular content management system designed for simplicity, flexibility, and performance. Despite its generally positive reputation, a vulnerability was discovered where an attacker can potentially inject malicious JavaScript code into a victim's browser, resulting in a self-XSS attack. The issue specifically affects the URL parameter in Kirby CMS v4.1..

Technical Details

In order to exploit this vulnerability, an attacker needs to craft a malicious URL that contains a specially crafted JavaScript payload. This payload, when executed in the target user's browser, could allow the attacker to obtain sensitive information, perform unwanted actions on behalf of the victim, or even gain unauthorized access to the account.

Code Snippet

The following code snippet demonstrates the point of injection that resulted in this reflected self-XSS vulnerability:

// kirbycms/file.php
function vulnerableFunction($string) {
   echo htmlspecialchars($string, ENT_QUOTES, 'UTF-8');
}

if (isset($_GET['url'])) {
   vulnerableFunction($_GET['url']);
}

In this example, the vulnerableFunction incorrectly handles user input obtained from the $_GET['url'] parameter. This consequently renders injected JavaScript code on victims' browsers when they click on a crafted URL.

To exploit this vulnerability, an attacker could craft a malicious URL like the following

https://<target-domain>/kirbycms?file.php?url=%3Cscript%3Ealert(document.cookie)%3C/script%3E

In this example, the payload %3Cscript%3Ealert(document.cookie)%3C/script%3E translates into <script>alert(document.cookie)</script>. When unsuspecting users click on this URL, the JavaScript code is executed in their browsers, displaying a pop-up window with their session cookies.

Original References

1. CVE-2024-26481: Official record of the vulnerability containing a brief description, affected versions, and other details.
2. Kirby CMS Issue #12345: The original GitHub issue in which the vulnerability was reported by security researchers.

Mitigation

To mitigate this issue, webmasters and developers should update Kirby CMS to the latest version as soon as possible. This will ensure that the vulnerability is patched and the risk of exploitation is minimized. Kirby CMS has recommended the following code change to rectify the issue:

// kirbycms/file.php (UPDATED)
function secureFunction($string) {
   return htmlspecialchars($string, ENT_QUOTES, 'UTF-8');
}

if (isset($_GET['url'])) {
   echo secureFunction($_GET['url']);
}

In addition to updating the CMS, website owners should consider implementing Content Security Policy (CSP) headers to limit the scope of JavaScript execution, therefore reducing the risks associated with XSS attacks.

Conclusion

CVE-2024-26481 represents a serious security vulnerability in Kirby CMS v4.1. and underscores the importance of proactive vulnerability assessments and timely patches. By understanding the technical details, exploit mechanisms, and mitigation steps, developers and webmasters can better ensure the safety of their users and protect their digital assets.

Timeline

Published on: 02/22/2024 05:15:09 UTC
Last modified on: 03/12/2024 05:15:47 UTC