Exploitation Research Plan - CVE-2025-68882 (Scalenut)

1. Vulnerability Summary

The Scalenut plugin (up to version 1.1.3) for WordPress contains a missing authorization vulnerability. Specifically, a function registered as an AJAX handler (likely via wp_ajax_nopriv_) fails to perform adequate capability checks (e.g., current_user_can('manage_options')). This oversight allows unauthenticated attackers to invoke sensitive administrative actions, such as updating plugin configurations or API keys, leading to full control over the plugin's integration with the Scalenut service.

2. Attack Vector Analysis

• Endpoint: /wp-admin/admin-ajax.php
• Action: scalenut_save_settings or scalenut_update_api_token (inferred based on plugin functionality; to be verified in source).
• HTTP Method: POST
• Payload Parameters:
  • action: The vulnerable AJAX action name.
  • nonce: (If applicable) The nonce required for the action.
  • scalenut_api_key or token: The malicious value to inject into the site settings.
• Authentication: None required (unauthenticated).
• Preconditions: The plugin must be active.

3. Code Flow

1. Registration: The plugin registers an AJAX action for unauthenticated users:
   add_action('wp_ajax_nopriv_scalenut_save_settings', array($this, 'scalenut_save_settings')); (inferred).
2. Invocation: An attacker sends a POST request to admin-ajax.php with action=scalenut_save_settings.
3. Execution: The scalenut_save_settings function is called.
4. Failure Point: The function likely checks for a nonce but fails to check for current_user_can('manage_options').
5. Sink: The function calls update_option('scalenut_settings', ...) or update_option('scalenut_api_key', ...) using user-supplied input from $_POST.

4. Nonce Acquisition Strategy

If the handler uses check_ajax_referer or wp_verify_nonce, we must extract the nonce from the frontend.

1. Identify Script Localization: Look for wp_localize_script in the plugin source (likely in inc/class-scalenut.php or admin/class-scalenut-admin.php).
2. Localization Keys: Search for the object name and key (e.g., scalenut_ajax_object.nonce).
3. Extraction:
   • Step A: Create a post/page to ensure the plugin's frontend scripts are loaded if they are conditional:
     wp post create --post_type=page --post_status=publish --post_title="Scalenut Proof" --post_content="[scalenut_content]" (Shortcode inferred).
   • Step B: Use browser_navigate to visit the page.
   • Step C: Use browser_eval to extract the nonce:
     browser_eval("window.scalenut_ajax_object?.nonce") (inferred).

Note: If wp_ajax_nopriv_ is used, the nonce is often exposed to unauthenticated users to allow legitimate frontend interactions.

5. Exploitation Strategy

Once the vulnerable action and any required nonce are identified:

1. Construct the POST Request:

   • URL: http://localhost:8080/wp-admin/admin-ajax.php
   • Headers: Content-Type: application/x-www-form-urlencoded
   • Body: action=scalenut_save_settings&nonce=[NONCE]&api_key=EVIL_TOKEN_123&settings[option_name]=malicious_value

2. Send via http_request:

{
  "method": "POST",
  "url": "http://localhost:8080/wp-admin/admin-ajax.php",
  "headers": {
    "Content-Type": "application/x-www-form-urlencoded"
  },
  "body": "action=scalenut_save_settings&nonce=abc123def4&api_key=pwned_key"
}

6. Test Data Setup

1. Install Plugin: Ensure Scalenut 1.1.3 is installed and active.
2. Initial State: Verify the current API key is empty or set to a default value.
   • wp option get scalenut_api_key (inferred option name).
3. Public Page: If a nonce is required, publish a page that enqueues the Scalenut script.

7. Expected Results

• The AJAX request should return a 200 OK response, often with a JSON body: {"success": true}.
• The WordPress database will be updated with the attacker-controlled value.

8. Verification Steps

1. Check Database: Use WP-CLI to confirm the option was changed:
   • wp option get scalenut_api_key
   • Result should be: pwned_key
2. Admin UI Check: Log in as an administrator and navigate to the Scalenut settings page to see the injected value in the "API Key" or "Settings" field.

9. Alternative Approaches

• Missing Nonce Check: If check_ajax_referer is entirely missing, the exploit becomes a direct POST request without the "Nonce Acquisition" step.
• REST API Endpoint: Search for register_rest_route with a permission_callback that returns true or is missing entirely.
  • Path: /wp-json/scalenut/v1/save-settings (inferred).
  • Exploit via http_request to the REST path.
• Settings API Injection: If the plugin registers settings via register_setting but does not properly restrict the admin-post.php or admin-ajax.php access to those settings.