CVE-2024-50428

Executive Summary

CVE-2024-50428 identifies a Missing Authorization vulnerability in the Mondula Multi Step Form WordPress plugin, affecting versions up to and including 1.7.21. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized data access or manipulation of form submissions. The vulnerability is classified as a WordPress ecosystem issue, not related to the underlying web server (Apache/Nginx). With a CVSS score of 4.3 (Medium), the risk is elevated due to the lack of authentication required for exploitation. No public proof-of-concept (PoC) or exploit code has been released, and the patch status remains unknown, making this a significant concern for sites using the plugin.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. As such, it is part of the WordPress supply chain. Users must monitor the plugin’s update channel for a patched version. No NPM, PyPI, Go, or Ruby packages are involved.

CVSS Breakdown & Threat Level

• CVSS Score: 4.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Attack Vector (AV): Network – Exploitable remotely.
• Attack Complexity (AC): Low – No special conditions required.
• Privileges Required (PR): None – No authentication needed.
• User Interaction (UI): None – No user action required.
• Scope (S): Unchanged – Exploit does not affect other components.
• Confidentiality (C): Low – Limited data exposure possible.
• Integrity (I): None – No data modification.
• Availability (A): None – No denial of service.

Threat Level: Medium. The low complexity and no privileges required make it attractive for attackers, but the impact is limited to low confidentiality loss.

Deep Dive & Mechanics

The vulnerability stems from Missing Authorization (CWE-862) in the Mondula Multi Step Form plugin. The plugin likely exposes REST API endpoints or AJAX actions that handle form submissions or data retrieval without proper capability checks. An unauthenticated attacker can send crafted HTTP requests to these endpoints, bypassing access controls intended for administrators or authenticated users.

Root Cause: The plugin fails to verify user permissions before executing sensitive operations, such as viewing submitted form data, modifying form configurations, or accessing stored entries. This is a classic case of incorrectly configured access control security levels.

Attack Vector: The attacker sends a specially crafted HTTP request (e.g., GET or POST) to a vulnerable endpoint. For example, an endpoint like /wp-json/mondula/v1/entries might return all form submissions without authentication.

Impact: An attacker could enumerate form submissions, extract sensitive user data (e.g., email addresses, personal details), or manipulate form settings. The exact impact depends on the plugin’s functionality.

Vulnerable vs. Patched Code

Since no patch is available, we can only hypothesize the vulnerable code pattern. The plugin likely uses WordPress functions like wp_ajax_* or wp_ajax_nopriv_* without proper nonce or capability checks.

Vulnerable Code Example (Hypothetical):

add_action('wp_ajax_nopriv_mondula_get_entries', 'mondula_get_entries');
function mondula_get_entries() {
    // No capability check
    $entries = get_option('mondula_entries');
    wp_send_json($entries);
}

Patched Code Example (Hypothetical):

add_action('wp_ajax_mondula_get_entries', 'mondula_get_entries');
function mondula_get_entries() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized');
    }
    $entries = get_option('mondula_entries');
    wp_send_json($entries);
}

The patch would add a capability check (e.g., current_user_can('manage_options')) and remove the nopriv action to restrict access to authenticated users.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target WordPress site with Multi Step Form plugin <= 1.7.21.
• No authentication required.

Exploitation Steps:

1. Identify vulnerable endpoints using directory brute-forcing or plugin source analysis.
2. Send a crafted HTTP request to the endpoint (e.g., /wp-json/mondula/v1/entries).
3. Parse the JSON response to extract sensitive data.

Example Request (using curl):

curl -X GET "http://target.com/wp-json/mondula/v1/entries" -H "User-Agent: Mozilla/5.0"

Expected Response:

{
  "entries": [
    {"id": 1, "name": "John Doe", "email": "john@example.com", "message": "Test"}
  ]
}

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual HTTP requests to /wp-json/mondula/v1/* or /wp-admin/admin-ajax.php with action parameters related to the plugin.
• Look for requests from unauthenticated users to endpoints that should require authentication.

Defense:

• Immediately disable the plugin if no patch is available.
• Implement a Web Application Firewall (WAF) rule to block requests to known vulnerable endpoints.
• Restrict access to /wp-json/ endpoints using .htaccess or server configuration.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP requests to /wp-json/mondula/v1/entries or similar endpoints.
• Unusual GET/POST requests to /wp-admin/admin-ajax.php with action=mondula_* parameters.

File IOCs:

• Modified plugin files in /wp-content/plugins/multi-step-form/.
• Unexpected log entries in WordPress debug log.

Behavioral IOCs:

• Unauthorized access to form submission data.
• Anomalous traffic patterns from a single IP to plugin-specific endpoints.

Detection Engineering

YARA Rule

rule CVE_2024_50428_Mondula_MultiStepForm {
    meta:
        description = "Detects vulnerable Mondula Multi Step Form plugin files"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-50428"
    strings:
        $vuln_func = "wp_ajax_nopriv_mondula" nocase
        $vuln_endpoint = "mondula/v1/" nocase
    condition:
        $vuln_func or $vuln_endpoint
}

Sigma Rule

title: CVE-2024-50428 - Mondula Multi Step Form Unauthorized Access
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects attempts to exploit missing authorization in Mondula Multi Step Form plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 
            - '/wp-json/mondula/v1/'
            - 'action=mondula_'
    condition: selection
falsepositives:
    - Legitimate admin requests (if authenticated)
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-50428 - Mondula Multi Step Form Unauthorized Access Attempt"; flow:to_server; http.method; content:"GET"; http.uri; content:"/wp-json/mondula/v1/"; nocase; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Review server logs for any unauthorized access to plugin endpoints.
3. Implement a WAF rule to block requests to /wp-json/mondula/v1/* from unauthenticated users.

Long-term Fix:

• Monitor the WordPress plugin repository for an official patch.
• Apply the patch as soon as it becomes available.
• Consider replacing the plugin with an alternative that has active security support.

Workaround:

• Add the following .htaccess rule to block access to vulnerable endpoints:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REQUEST_URI} ^/wp-json/mondula/v1/ [NC]
RewriteCond %{HTTP_COOKIE} !wordpress_logged_in [NC]
RewriteRule .* - [F,L]
</IfModule>

Valters IT Signature:
This report was generated by Valters IT DevSecOps AI. All information is based on publicly available data and should be verified before action.