Recently, a new vulnerability in Subrion CMS 4.2.1 was discovered, categorized as Cross-Site Scripting (XSS). This vulnerability has been assigned the CVE number CVE-2024-25399. The flaw lies within adminer.php, and allows an attacker to execute malicious scripts on a user's browser. This post aims to describe the exploit in detail and provide necessary mitigation to secure your Subrion CMS installation.

Background

Cross-Site Scripting (XSS) vulnerabilities are among the most common security issues reported in web applications. They occur when an application includes untrusted data on a web page without proper validation. This allows an attacker to execute malicious scripts in the context of the user's browser. Such vulnerabilities can lead to a wide range of security issues, such as session theft, defacement, and phishing.

Details and Exploit

The adminer.php file in Subrion CMS 4.2.1 contains an endpoint that's susceptible to XSS attacks. This vulnerability is caused by unsanitized user input being rendered directly into the HTML output. An attacker can craft a malicious URL containing a script that executes when a user visits the page.

Here's an example URL exploiting this vulnerability

http://example.com/adminer.php?callback=<script>alert('XSS')</script>;

When an admin or user visits this URL, their browser will execute the malicious JavaScript code embedded within the <script> tags.

Proof of Concept (PoC) code exploiting this vulnerability

var url = "http://example.com/adminer.php?callback=<script>alert('XSS')</script>;";
window.location = url;

Mitigation

To mitigate against this vulnerability, it's essential to implement proper input validation and encoding to reflect user-generated content. As of now, there is no official patch available for Subrion CMS 4.2.1. Until a patch is released, the following temporary fix can be applied:

Edit the adminer.php file and make sure to sanitize the callback parameter before it's rendered to the HTML output.

Replace the following line of code near line 18

echo($_GET["callback"]) . "(" . $adminer->credentialsProcess() . ");";

With

$callback = htmlspecialchars($_GET["callback"], ENT_QUOTES, 'UTF-8');
echo $callback . "(" . $adminer->credentialsProcess() . ");";

This will sanitize the user input, escaping any harmful characters and preventing XSS attacks.

Conclusion

Being proactive about security is essential in today's digital landscape. Keeping your software up-to-date and addressing vulnerabilities as soon as they are discovered is a key component of maintaining a secure environment. Be sure to monitor the Subrion CMS GitHub repository and website for future updates on this vulnerability and any others that may be discovered.

1. CVE-2024-25399 - National Vulnerability Database (NVD)
2. Subrion CMS GitHub Repository

Timeline

Published on: 02/27/2024 16:15:46 UTC
Last modified on: 11/21/2024 09:00:44 UTC