Magneticlab Sàrl, a renowned software company, developed the Homepage Pop-up plugin, which is designed to display pop-up notifications on the main page of a website seamlessly. Recently, however, a security research team discovered a Stored Cross-Site Scripting (XSS) vulnerability in the plugin (<= 1.2.5 versions). This blog post aims to dig deeper into the exploit and dissect its potential implications. We will also reveal how the vulnerability, dubbed CVE-2022-43480, can be mitigated.
The Vulnerability: Overview
CVE-2022-43480 is an authenticated (admin+) stored XSS vulnerability found in the Homepage Pop-up plugin's <= 1.2.5 versions. Attackers who manage to exploit this vulnerability can execute arbitrary JavaScript code in the context of a victim user's browser, potentially leading to sensitive data leakage, unauthorized actions, or full account compromise.
The Root Cause
Upon investigating the plugin's source code, it was found that user input was not sufficiently sanitized before being stored or rendered. More specifically, when an administrator creates or edits a pop-up notification, the plugin's save_postdata() function fails to properly filter the user-supplied input. The vulnerable code snippet is as follows (found in magneticlab-homepage-popup.php):
function save_postdata($post_id) {
global $post;
if ( ! empty( $_POST['magneticlab_home_popup_nonce'] ) && wp_verify_nonce( $_POST['magneticlab_home_popup_nonce'], 'my_theme_admin' ) ) {
// Gather input and save
update_post_meta($post_id, "_nhp_link",
strip_tags($_POST["_nhp_link"], '<a><iframe><div><script>'));
}
}
In the above code, the strip_tags() function is used to remove unwanted HTML tags, but it fails to strip the potentially malicious <script> tag. Consequently, an attacker could inject arbitrary JavaScript code inside the _nhp_link textarea field, exploiting the stored XSS vulnerability.
Access to an admin or higher-privileged account on the target WordPress site.
2. The vulnerable Homepage Pop-up plugin (<= 1.2.5 versions) should be installed and active on the target site.
In the "_nhp_link" textarea field, enter the JS payload with the <script> tag, such as
<script>alert('XSS')</script>
Save the pop-up notification.
5. Once the pop-up notification is displayed on the website's main page, any user that visits it will trigger the XSS payload, executing the attacker's arbitrary JavaScript code in their browser context.
Mitigation Recommendations
To protect against this vulnerability, users of the Homepage Pop-up plugin should immediately take these preventive measures:
1. Update the plugin to its latest version, as the developers have addressed this vulnerability in subsequent releases.
Make sure that only trusted users have admin or higher-level privileges on your WordPress site.
3. Conduct regular security audits and source code reviews to identify and rectify vulnerabilities in your web applications and plugins.
Original References
Readers interested in a deeper understanding of this vulnerability can find the relevant documentation and references below:
1. CVE-2022-43480 Details - Official documentation from the CVE database.
2. Magneticlab Homepage Pop-up plugin - The official WordPress plugin repository page for the Homepage Pop-up plugin.
Conclusion
CVE-2022-43480 highlights the criticality of thoroughly sanitizing user inputs and ensuring that potential vulnerabilities are promptly addressed. By keeping plugins and applications up to date, restricting high-level access to trusted users, and conducting regular security audits, WordPress users can significantly reduce their vulnerability risks and protect their websites from attacks.
Timeline
Published on: 04/16/2023 09:15:00 UTC
Last modified on: 04/21/2023 04:16:00 UTC