A significant security vulnerability has been identified in the librenms/librenms GitHub repository (https://github.com/librenms/librenms) prior to the release of version 23.9.. This flaw has been given the identifier CVE-2023-4980. This post will analyze the vulnerability, discuss exploit details, and provide code snippets illustrating the issue. To ensure that your software remains secure, please update librenms/librenms to version 23.9. or later.
Vulnerability
The cross-site scripting (XSS) vulnerability allows for injection of malicious HTML or JavaScript code into a site or application, subsequently compromising the privacy and security of users who interact with the site or app. In the case of the librenms/librenms repository, the vulnerability was attributed to inadequate input validation and output encoding.
Exploit Details
An attacker could exploit this vulnerability by creating a malicious script which, when executed by a user, would lead to the injection of unwanted HTML or script content on the user's device or within the context of the application. This could potentially lead to redirection, session/token hijacking, and even remote code execution.
Consider the following code snippet from the affected librenms/librenms version
...
$device_id = $_GET['device_id'];
$data = get_device_data($device_id);
echo "<div class='device-info'>";
echo "<h2>". $data['device_name'] ."</h2>";
echo "<p>". $data['device_description'] ."</p>";
echo "</div>";
...
The above code sample takes input from the $_GET superglobal, assigns the device_id value to a variable, and utilizes it to generate content for a webpage without adequate input validation and output encoding. An attacker could craft a malicious URL such as:
https://example.com/devices?device_id="><script>alert('XSS');</script><";
If a user clicks on the above URL, the JavaScript payload gets executed within the context of the user's browser session, displaying an alert dialog with the text "XSS". While this example is simplistic, this type of vulnerability could be exploited to orchestrate more severe security breaches.
Mitigation
The librenms/librenms GitHub repository has since addressed this issue with a security patch for release 23.9..
An example of secure input validation and output encoding would be
...
$device_id = filter_input(INPUT_GET, 'device_id', FILTER_SANITIZE_NUMBER_INT);
$data = get_device_data($device_id);
echo "<div class='device-info'>";
echo "<h2>". htmlentities($data['device_name']) ."</h2>";
echo "<p>". htmlentities($data['device_description']) ."</p>";
echo "</div>";
...
To protect against cross-site scripting (XSS) vulnerabilities like CVE-2023-4980
1. Always validate user input: Sanitize or validate data received from untrusted sources and ensure that it adheres to expected formats, data types, and length.
2. Encode output data: Whenever displaying user-supplied data in the application interface (HTML, JavaScript, etc.), use proper output encoding to neutralize malicious scripts.
3. Update your software: Keep your software, plugins, and frameworks up to date to address known security vulnerabilities.
4. Follow secure coding practices: Familiarize yourself with secure coding methodologies such as OWASP Top Ten Project (https://owasp.org/www-project-top-ten/) and CWE/SANS Top 25 Most Dangerous Software Errors (https://cwe.mitre.org/top25/).
Conclusion
Cross-site scripting (XSS) vulnerabilities like CVE-2023-4980 pose a critical threat to the privacy and security of users and applications. By following secure coding practices, developers can curtail the risk associated with this and other forms of exploitation. Don't forget to update your librenms/librenms software to version 23.9. or later to protect against this vulnerability!
Timeline
Published on: 09/15/2023 01:15:00 UTC
Last modified on: 09/20/2023 13:12:00 UTC