Exploitation Research Plan - CVE-2025-67969

1. Vulnerability Summary

The UPI QR Code Payment Gateway for WooCommerce plugin (<= 1.5.1) contains a missing authorization vulnerability. Specifically, an administrative or sensitive function is exposed via an AJAX handler or a hook (likely admin_init or wp_ajax_nopriv_*) without a corresponding capability check (like current_user_can( 'manage_options' )). This allows an unauthenticated attacker to perform actions such as modifying plugin settings, which could include changing the UPI ID (VPA) or merchant details, effectively hijacking payments.

2. Attack Vector Analysis

• Endpoint: /wp-admin/admin-ajax.php
• Action: uqcp_save_settings (inferred based on plugin naming conventions) or a similar handler.
• Parameters: Likely action, uqcp_upi_id (or vpa), uqcp_merchant_name, and a nonce.
• Authentication: Unauthenticated (leveraging wp_ajax_nopriv_ or admin_init).
• Preconditions: The plugin must be active and configured with WooCommerce.

3. Code Flow

1. Entry Point: An unauthenticated request is sent to admin-ajax.php.
2. Hook Registration: The plugin registers a handler in includes/class-upi-qr-payment-gateway-woocommerce.php (inferred) or admin/class-upi-qr-admin.php (inferred) using:
   add_action( 'wp_ajax_nopriv_uqcp_save_settings', array( $this, 'save_settings' ) );
   OR a function is hooked to admin_init which executes on every request to admin-ajax.php.
3. Vulnerable Function: The callback function (e.g., save_settings) is called.
4. Missing Check: The function performs update_option() or similar database operations without verifying the user's permissions via current_user_can().
5. Sink: The update_option() function persists the attacker-supplied settings (e.g., a malicious UPI ID).

4. Nonce Acquisition Strategy

If the vulnerable endpoint requires a nonce for verification via check_ajax_referer() or wp_verify_nonce(), follow this strategy:

1. Identify the Localization: Search the source code for wp_localize_script to find the JS object and nonce key.
   • Search Command: grep -r "wp_localize_script" .
   • Likely JS Variable: window.uqcp_admin_vars or window.uqcp_vars (inferred).
   • Likely Nonce Key: nonce or uqcp_nonce.
2. Locate the Triggering Page: Identify if the script is enqueued on the plugin's settings page or a public WooCommerce checkout/product page.
3. Create a Triggering Page: If the nonce is only loaded for certain shortcodes:
   • wp post create --post_type=page --post_status=publish --post_content='[upi_qr_code]' (inferred shortcode).
4. Extract via Browser:
   • Navigate to the page.
   • Use browser_eval("window.uqcp_vars?.nonce") to retrieve the valid token.

5. Exploitation Strategy

We will attempt to change the Merchant UPI ID (VPA) to an attacker-controlled address.

• Request URL: http://localhost:8080/wp-admin/admin-ajax.php
• Method: POST
• Content-Type: application/x-www-form-urlencoded
• Payload (Draft):

  action=uqcp_save_settings&
  uqcp_upi_id=attacker@upi&
  uqcp_merchant_name=Attacker+Merchant&
  security=[NONCE_OBTAINED_IN_STEP_4]
  

• Step-by-Step:
  1. Confirm the exact action name and parameter names by grepping the source for update_option inside functions registered to wp_ajax.
  2. Obtain the nonce if required (as per Section 4).
  3. Send the http_request with the payload to update the UPI ID.
  4. Verify the change.

6. Test Data Setup

1. Install WooCommerce: Ensure WooCommerce is active.
2. Enable Plugin: Activate "UPI QR Code Payment Gateway for WooCommerce".
3. Initial Configuration: Set a dummy UPI ID in the plugin settings (e.g., original@upi).
4. Page Creation: Create a page containing the plugin's QR display shortcode to ensure scripts and nonces are loaded.

7. Expected Results

• The admin-ajax.php response should indicate success (e.g., {"success":true} or 1).
• The uqcp_upi_id (or equivalent) option in the WordPress database should be updated to attacker@upi.

8. Verification Steps

1. WP-CLI Check:
   • wp option get uqcp_upi_id (or the actual option name found during research).
2. Checkout Verification:
   • Add a product to the cart and proceed to checkout.
   • Select the UPI QR payment method.
   • Inspect the generated QR code or data-attributes to confirm it now uses attacker@upi.

9. Alternative Approaches

• Settings Save via admin_init: If the vulnerability is in an admin_init hook, the request might not need an action parameter in the body but rather specific GET/POST parameters that trigger the save logic when is_admin() is false (as admin_init still fires).
• Direct Option Update: If the plugin uses a generic save_options function, try to pass arbitrary option names to change other critical site settings (e.g., users_can_register).