Exploitation Research Plan - CVE-2026-25011

1. Vulnerability Summary

The WP Custom Admin Interface plugin (versions <= 7.41) contains a missing authorization vulnerability. Specifically, several AJAX actions and/or initialization hooks lack a current_user_can('manage_options') check. This allows authenticated users with Subscriber-level permissions to perform administrative actions such as modifying plugin settings, resetting admin menus, or injecting custom content into the admin interface.

2. Attack Vector Analysis

• Vulnerable Endpoints:
  1. /wp-admin/admin-ajax.php (Primary)
  2. /index.php (via query parameters, per the plugin's "delete-menu" feature)
• Vulnerable Actions:
  • wp_ajax_wp_custom_admin_interface_save_settings
  • wp_ajax_wp_custom_admin_interface_reset_settings
  • wp_custom_admin_interface_delete_menu (via init hook)
• Required Capability: Subscriber level access (PR:L).
• Payload Parameters:
  • action: wp_custom_admin_interface_save_settings
  • security: The nonce value.
  • data: A serialized string or object containing the settings to be updated.

3. Code Flow

1. Registration: The plugin registers AJAX handlers in wp-custom-admin-interface.php (or an included settings file) using add_action( 'wp_ajax_wp_custom_admin_interface_save_settings', ... ).
2. Missing Check: The handler function (e.g., wp_custom_admin_interface_save_settings()) uses check_ajax_referer( 'wp_custom_admin_interface_nonce', 'security' ) to verify the nonce but fails to call current_user_can( 'manage_options' ).
3. Execution: Since wp_ajax_ hooks are available to any logged-in user, and Subscribers can access the dashboard to receive the enqueued nonce, they can trigger the function.
4. Sink: The function calls update_option(), allowing the Subscriber to overwrite the plugin's configuration.

4. Nonce Acquisition Strategy

The plugin enqueues its settings script and localizes a nonce for AJAX operations. Although the settings page is restricted, the script is often enqueued globally in the admin area.

1. Navigate to Dashboard: Log in as a Subscriber and go to /wp-admin/index.php.
2. Extract Nonce: Use browser_eval to extract the nonce from the localized JavaScript object.
   • JS Object: window.wp_custom_admin_interface_settings (inferred from plugin slug)
   • Key: nonce
   • Command: browser_eval("window.wp_custom_admin_interface_settings?.nonce")
3. Alternative: If not localized there, search the page source for any string containing wp_custom_admin_interface_nonce.

5. Exploitation Strategy

We will attempt to modify the Admin Footer Text setting to demonstrate unauthorized integrity modification.

Step-by-Step Plan:

1. Pre-exploitation: As Admin, set the footer text to "Original Admin Footer".
2. Authentication: Authenticate as a Subscriber.
3. Nonce Capture: Use the browser to navigate to /wp-admin/index.php and extract the security nonce from window.wp_custom_admin_interface_settings.nonce.
4. Execution: Send a POST request to admin-ajax.php to overwrite settings.
   • URL: http://vulnerable-test.local/wp-admin/admin-ajax.php
   • Method: POST
   • Content-Type: application/x-www-form-urlencoded
   • Body:

     action=wp_custom_admin_interface_save_settings&security=[NONCE]&data=wp_custom_admin_interface_general_settings%5Bfooter_text%5D=Exploited+by+Subscriber
     

   • Note: If data requires a JSON string instead of form-encoded, adjust the payload accordingly.

6. Test Data Setup

1. Users:
   • Admin: admin / password
   • Subscriber: attacker / password
2. Plugin Configuration:
   • Ensure the plugin is active.
   • As Admin, go to Custom Admin Interface > General Settings and set "Custom Footer Text" to "Standard Footer".
   • Save changes.

7. Expected Results

• The AJAX request should return a 200 OK or a JSON success response (e.g., {"success":true}).
• The WordPress database option wp_custom_admin_interface_general_settings should now contain "Exploited by Subscriber" in the footer_text field.

8. Verification Steps

1. Check via WP-CLI:

   wp option get wp_custom_admin_interface_general_settings --format=json
   

   Verify that the footer_text value has changed.
2. Check Admin UI: Log in as Admin and navigate to any admin page. Scroll to the bottom and verify the footer text has been modified to "Exploited by Subscriber".

9. Alternative Approaches

The "Delete Menu" Bypass

The readme.txt mentions a feature to delete menus via a GET parameter. If the AJAX path fails, try this:

• URL: http://vulnerable-test.local/index.php?wp-custom-admin-interface=delete-menu
• Method: GET (while logged in as Subscriber)
• Verification: Check if the option wp_custom_admin_interface_admin_menu_settings is deleted:

  wp option get wp_custom_admin_interface_admin_menu_settings
  

  (Expected: "Error: Could not find 'wp_custom_admin_interface_admin_menu_settings' option.")