CVE-2023-6496

Executive Summary

CVE-2023-6496 is a Missing Authorization vulnerability in the Manage Notification E-mails WordPress plugin, affecting all versions up to and including 1.8.5. The flaw resides in the card_famne_export_settings function, which fails to properly enforce access controls. This allows any unauthenticated attacker to export the plugin’s configuration settings, potentially exposing sensitive data such as email templates, notification rules, and other internal configurations. The vulnerability has a CVSS score of 5.3 (Medium) and an EPSS score of 0.0%, indicating low exploitation likelihood at this time. However, due to the ease of exploitation (no authentication required) and the potential for information disclosure, this issue warrants immediate attention.

WordPress Ecosystem Impact

This vulnerability is specific to the WordPress plugin ecosystem. The Manage Notification E-mails plugin is widely used to customize email notifications sent by WordPress. An attacker exploiting this flaw can retrieve the plugin’s settings, which may include email addresses, notification triggers, and other configuration details that could aid in further attacks.

CVSS Breakdown & Threat Level

• CVSS Score: 5.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• 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: Low (C:L)
• Integrity Impact: None (I:N)
• Availability Impact: None (A:N)

Threat Level: Medium. The vulnerability allows unauthenticated attackers to read plugin settings, which may contain sensitive information. While the direct impact is limited to confidentiality, the exposed data could be leveraged for more targeted attacks.

Deep Dive & Mechanics

The vulnerability exists in the card_famne_export_settings function, which is intended to export the plugin’s settings for backup or migration purposes. Due to a missing authorization check, this function can be called by any unauthenticated user via a direct request to the WordPress admin-ajax endpoint.

Root Cause: The function does not verify the user’s capabilities (e.g., manage_options) before executing the export. This is a classic case of Missing Authorization (CWE-862).

Attack Vector: An attacker can craft a POST request to /wp-admin/admin-ajax.php with the action parameter set to card_famne_export_settings. The server will then return the plugin’s settings in a serialized or JSON format.

Potential Impact:

• Disclosure of email notification templates.
• Exposure of email addresses used for notifications.
• Leakage of plugin configuration flags and rules.
• Information that could be used to craft phishing attacks or further compromise the site.

Vulnerable vs. Patched Code

Vulnerable Code (version <= 1.8.5):

add_action('wp_ajax_card_famne_export_settings', 'card_famne_export_settings');
function card_famne_export_settings() {
    // No capability check
    $settings = get_option('famne_settings');
    echo json_encode($settings);
    wp_die();
}

Patched Code (hypothetical fix):

add_action('wp_ajax_card_famne_export_settings', 'card_famne_export_settings');
function card_famne_export_settings() {
    // Added capability check
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $settings = get_option('famne_settings');
    echo json_encode($settings);
    wp_die();
}

The patch adds a current_user_can('manage_options') check to ensure only administrators can export settings.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with Manage Notification E-mails plugin version <= 1.8.5.
• No authentication required.

Exploitation Steps:

1. Identify the target WordPress site.
2. Send a POST request to /wp-admin/admin-ajax.php with the action parameter.
3. Parse the response to extract plugin settings.

Example cURL Command:

curl -X POST https://target-site.com/wp-admin/admin-ajax.php \
  -d "action=card_famne_export_settings"

Expected Response:

{
  "famne_settings": {
    "admin_email": "admin@example.com",
    "notification_rules": {...},
    "email_templates": {...}
  }
}

Blue Team (Detection & Defense)

Detection:

• Monitor for POST requests to /wp-admin/admin-ajax.php with action=card_famne_export_settings from unauthenticated sources.
• Look for anomalous spikes in admin-ajax traffic.

Defense:

• Immediately update the plugin to a patched version (if available).
• Implement a Web Application Firewall (WAF) rule to block requests to admin-ajax.php with the specific action parameter from unauthenticated users.
• Restrict access to admin-ajax.php via .htaccess or server configuration for non-logged-in users.

Indicators of Compromise (IOCs)

• Network IOCs:

  • POST requests to /wp-admin/admin-ajax.php with body containing action=card_famne_export_settings.
  • Responses containing JSON with keys like famne_settings, admin_email, notification_rules.

• File IOCs:

  • Unauthorized access logs showing the above request pattern.
  • Plugin settings file (if exported) containing sensitive configuration data.

• Behavioral IOCs:

  • Unauthenticated users triggering admin-ajax actions.
  • Sudden increase in 403 errors if a WAF is in place.

Detection Engineering

YARA Rule

rule Detect_CVE_2023_6496_Exploit {
    meta:
        description = "Detects exploitation attempts for CVE-2023-6496 in WordPress"
        author = "Valters IT"
        date = "2025-04-08"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2023-6496"
    strings:
        $ajax_action = "action=card_famne_export_settings"
        $admin_ajax = "/wp-admin/admin-ajax.php"
    condition:
        $ajax_action and $admin_ajax
}

Sigma Rule

title: CVE-2023-6496 Exploitation Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects unauthenticated POST requests to admin-ajax.php with the vulnerable action parameter
author: Valters IT
date: 2025-04-08
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: POST
        cs-uri-query|contains: "/wp-admin/admin-ajax.php"
        cs-uri-query|contains: "action=card_famne_export_settings"
    condition: selection
falsepositives:
    - Legitimate admin actions (if authenticated)
level: high

Suricata Rule

alert http any any -> any any (
    msg:"CVE-2023-6496 - Manage Notification E-mails Plugin Settings Export Attempt";
    flow:to_server,established;
    content:"POST";
    http_method;
    content:"/wp-admin/admin-ajax.php";
    http_uri;
    content:"action=card_famne_export_settings";
    http_client_body;
    classtype:attempted-recon;
    sid:10000001;
    rev:1;
    reference:cve,2023-6496;
)

Remediation & Mitigation

Immediate Actions:

1. Update the plugin: If a patched version is released, update to the latest version immediately.
2. Disable the plugin: If no patch is available, temporarily deactivate the Manage Notification E-mails plugin until a fix is applied.
3. Implement WAF rules: Block unauthenticated requests to admin-ajax.php with the vulnerable action parameter.

Long-term Measures:

• Conduct a security audit of all WordPress plugins to identify similar authorization flaws.
• Enforce the principle of least privilege for all AJAX actions.
• Regularly monitor WordPress security advisories and apply patches promptly.

Workaround:

• Add a capability check via a custom plugin or theme functions.php:

add_action('wp_ajax_card_famne_export_settings', function() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
}, 1);

Valters IT
Securing Digital Frontiers