CVE-2024-13346

Executive Summary

CVE-2024-13346 is a critical vulnerability in the Avada | Website Builder For WordPress & WooCommerce theme, affecting all versions up to and including 7.11.13. The flaw allows unauthenticated attackers to execute arbitrary shortcodes due to improper validation of user-supplied input before passing it to the do_shortcode() function. This can lead to unauthorized data access, content manipulation, and potential privilege escalation within the WordPress ecosystem. The vulnerability is classified as a WordPress-specific issue and does not involve Apache or Nginx.

Supply Chain & Package Security

This vulnerability resides in a commercial WordPress theme distributed via Themefusion. The theme is not available on public package registries like Packagist or WordPress.org, but it is commonly installed via manual upload or commercial license keys. Users should verify the integrity of their theme files and ensure they are sourced from official channels.

CVSS Breakdown & Threat Level

• CVSS Score: 7.3 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: Low

The vulnerability is easily exploitable by unauthenticated attackers, making it a high-priority target for threat actors.

Deep Dive & Mechanics

The vulnerability stems from the theme's failure to validate or sanitize user-supplied input before passing it to the do_shortcode() function. In WordPress, do_shortcode() processes shortcode tags within a string, executing any registered shortcode handlers. By injecting malicious shortcodes, an attacker can trigger arbitrary actions, such as:

• Executing PHP code via shortcodes like [eval] or custom shortcodes.
• Reading sensitive data via shortcodes that output database contents.
• Modifying posts or user roles via shortcodes that trigger administrative actions.

The attack vector is typically through HTTP POST requests to endpoints that accept shortcode input, such as custom AJAX handlers or form submissions.

Vulnerable vs. Patched Code

Vulnerable Code (<= 7.11.13):

// Example of vulnerable code in a theme function
function avada_process_shortcode($input) {
    // No validation or sanitization
    return do_shortcode($input);
}

Patched Code (Hypothetical):

function avada_process_shortcode($input) {
    // Validate and sanitize input
    $allowed_shortcodes = array('gallery', 'caption');
    $sanitized = wp_kses_allowed_html($input);
    // Only process allowed shortcodes
    return do_shortcode($sanitized);
}

The patched version would restrict shortcode execution to a whitelist of safe shortcodes and sanitize input to prevent arbitrary code execution.

Exploitation & Lab Setup

Red Team

1. Setup: Deploy a WordPress instance with Avada theme version 7.11.13.
2. Exploit: Send a crafted HTTP request to a vulnerable endpoint (e.g., /wp-admin/admin-ajax.php) with a malicious shortcode payload.

   POST /wp-admin/admin-ajax.php HTTP/1.1
   Host: target.com
   Content-Type: application/x-www-form-urlencoded
   
   action=avada_custom_action&shortcode=[wp_options]
   

   This shortcode could dump WordPress options, revealing database credentials.
3. Privilege Escalation: Use shortcodes like [user_register] or [add_role] to create admin accounts.

Blue Team

1. Detection: Monitor for unusual shortcode parameters in HTTP requests.
2. Mitigation: Implement a Web Application Firewall (WAF) rule to block requests containing do_shortcode or suspicious shortcode patterns.
3. Honeypot: Deploy a fake endpoint that logs and alerts on shortcode injection attempts.

Indicators of Compromise (IOCs)

• Network: HTTP requests with parameters containing shortcode= or do_shortcode.
• File: Modified wp-config.php or theme files with injected shortcode handlers.
• Log: WordPress debug logs showing do_shortcode calls with unexpected input.
• Database: New user accounts with elevated privileges or modified options.

Detection Engineering

YARA Rule

rule CVE_2024_13346_Shortcode_Injection {
    meta:
        description = "Detects Avada theme shortcode injection attempts"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-13346"
    strings:
        $shortcode_param = "shortcode=" nocase
        $do_shortcode = "do_shortcode" nocase
        $avada_action = "avada_" nocase
    condition:
        any of ($shortcode_param, $do_shortcode) and $avada_action
}

Sigma Rule

title: Avada Theme Shortcode Injection
id: 8f4b3c2a-1d5e-4f7a-9b8c-0d1e2f3a4b5c
status: experimental
description: Detects HTTP requests attempting to exploit CVE-2024-13346
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'shortcode='
        cs-uri-query|contains: 'avada_'
    condition: selection
falsepositives:
    - Legitimate use of shortcodes in admin area
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-13346 Avada Shortcode Injection"; flow:to_server,established; content:"POST"; http_method; content:"shortcode="; http_client_body; content:"avada_"; http_client_body; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Disable the vulnerable theme and switch to a secure alternative.
2. Short-term: Apply a WAF rule to block requests containing shortcode= and avada_ parameters.
3. Long-term: Monitor Themefusion for an official patch and apply it as soon as available.
4. Validation: Regularly audit WordPress themes for insecure do_shortcode() usage.

Valters IT
Securing Digital Frontiers