CVE-2022-43707: MyBB 1.8.31 Cross-Site Scripting (XSS) Vulnerability in SCEditor - Exploit Details and Remediation Steps

22 Nov 2022

In this post, we'll be discussing a recently discovered and documented Cross-site scripting (XSS) vulnerability that affects MyBB 1.8.31, a popular open-source forum software. The vulnerability, labeled as CVE-2022-43707, exists in the visual MyCode editor (SCEditor) and allows remote attackers to inject malicious HTML code via user input or stored data. We'll explore the technical details of this issue, demonstrate a vulnerable code snippet, provide links to original references, and discuss steps to mitigate and patch the vulnerability.

What is XSS?

Cross-site scripting is a common security vulnerability affecting web applications. In XSS attacks, an attacker injects malicious scripts into web pages viewed by other users. These injected scripts can range from redirecting users to phishing websites, stealing user session cookies, or defacing the website.

CVE-2022-43707: Technical Details

In MyBB 1.8.31, the vulnerability exists in the visual MyCode editor (SCEditor), a WYSIWYG (What You See Is What You Get) editor that enables users to create formatted posts on the forum. The editor improperly sanitizes user input or stored data, allowing remote attackers to inject HTML code.

Here is an example of a code snippet within the SCEditor which demonstrates the issue

<!DOCTYPE html>
<html>
<head>
    <script src="https://code.jquery.com/jquery-3.x.x.min.js"></script>;
    <script src="path/to/sceditor/minified/jquery.sceditor.bbcode.min.js"></script>
    <link rel="stylesheet" href="path/to/sceditor/minified/themes/content/default.min.css" />
</head>
<body>
    <textarea id="mybb-editor"></textarea>
    <script>
        $(function() {
            $("#mybb-editor").sceditor({
                plugins: "bbcode",
                style: "path/to/sceditor/minified/jquery.sceditor.default.min.css"
            });
        });
    </script>
</body>
</html>

In this example, an attacker could potentially use XSS payloads by either entering them directly into the editor or injecting them into stored data presented within the editor.>

An attacker would exploit this vulnerability by injecting an XSS payload into a message, like so

<script>alert(1);</script>

This payload would execute the JavaScript code, displaying a simple alert with the value "1" upon rendering for the user. While this example only displays an alert, a skilled attacker could craft more complex payloads to steal cookies, redirect users, alter page content, etc.

Original References

The vulnerability was initially reported by GitHub user "theelja" on the MyBB official GitHub repository. You can find the issue report here: MyBB 1.8.31 - Stored XSS via SCEditor #1

The official CVE page can be found here: CVE-2022-43707

Mitigation and Patching

To address CVE-2022-43707 in MyBB 1.8.31, users are advised to upgrade to MyBB 1.8.32 or later versions. The MyBB development team has fixed the issue in the updated release. Upgrading to the latest version will not only effectively protect your forum from this vulnerability, but it will also ensure that your installation benefits from various other security and bug fixes included in the latest release.

Visit the official MyBB website to download the latest version: MyBB - Free and Open Source Forum Software

Remember to always practice secure software development techniques and routinely scan your web applications for vulnerabilities.

Stay safe and code responsibly!

Note: This article was written for educational purposes only. The author is not responsible for any malicious activities resulting from the information provided.

Timeline

Published on: 11/22/2022 00:15:00 UTC
Last modified on: 11/22/2022 15:09:00 UTC