CVE-2024-11410

Executive Summary

CVE-2024-11410 is a Stored Cross-Site Scripting (XSS) vulnerability in the YooBar WordPress plugin (versions up to and including 2.0.6). The flaw resides in the plugin’s settings panel, where insufficient input sanitization and output escaping allow authenticated attackers with at least Contributor-level access to inject arbitrary web scripts. When an administrator or other user visits a page containing the injected script, it executes in their browser, potentially leading to session hijacking, defacement, or redirection to malicious sites.

This vulnerability is specific to the WordPress ecosystem and does not affect the underlying web server (Apache/Nginx). The plugin is used to display announcement, notification, advertisement, and promotion bars on WordPress sites.

Supply Chain & Package Security

This is a WordPress plugin vulnerability. The plugin is distributed via the official WordPress plugin repository. Users should verify they are running version 2.0.7 or later once a patch is released. No NPM, PyPI, Go, or Ruby packages are involved.

CVSS Breakdown & Threat Level

• CVSS Score: 6.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (Contributor-level)
• User Interaction: None
• Scope: Changed (impact on other components)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

Threat Level: Medium. The vulnerability requires authentication, but Contributor-level access is relatively easy to obtain in multi-author WordPress sites. The stored XSS can be used to target administrators, leading to full site compromise.

Deep Dive & Mechanics

The YooBar plugin stores its configuration (including bar content) in the WordPress database via the plugin’s settings page. The vulnerability occurs because the plugin does not properly sanitize user input before storing it, and does not escape the output when rendering the bar on the frontend.

Attack Flow:

1. An attacker with Contributor-level access logs into WordPress.
2. The attacker navigates to the YooBar settings page (e.g., /wp-admin/admin.php?page=yoobar-settings).
3. The attacker injects a malicious JavaScript payload into one of the text fields (e.g., bar message, announcement text).
4. The plugin stores the unsanitized payload in the wp_options table.
5. When any user (including administrators) visits a page where the YooBar is displayed, the payload executes in their browser.

Root Cause: The plugin uses update_option() to save settings without applying sanitize_text_field() or wp_kses() on the input, and outputs the value directly using echo without esc_html() or wp_kses_post().

Vulnerable vs. Patched Code

Vulnerable Code (version 2.0.6):

// In yoobar.php or similar
function yoobar_save_settings() {
    if ( isset($_POST['yoobar_message']) ) {
        update_option('yoobar_message', $_POST['yoobar_message']); // No sanitization
    }
}

function yoobar_display_bar() {
    $message = get_option('yoobar_message');
    echo '<div class="yoobar">' . $message . '</div>'; // No escaping
}

Patched Code (hypothetical fix):

function yoobar_save_settings() {
    if ( isset($_POST['yoobar_message']) ) {
        update_option('yoobar_message', sanitize_text_field($_POST['yoobar_message'])); // Sanitized
    }
}

function yoobar_display_bar() {
    $message = get_option('yoobar_message');
    echo '<div class="yoobar">' . esc_html($message) . '</div>'; // Escaped
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• WordPress site with YooBar plugin <= 2.0.6
• Valid user account with Contributor-level privileges

Exploitation Steps:

1. Log in to WordPress as a Contributor.
2. Navigate to YooBar Settings in the admin menu.
3. In the "Bar Message" field, enter the following payload:

   <script>alert('XSS')</script>
   

4. Click "Save Changes".
5. Visit any frontend page where the YooBar is active. The JavaScript will execute.

Advanced Payload (Session Hijacking):

<script>
fetch('/wp-admin/admin-ajax.php?action=your_custom_action', {
    method: 'POST',
    credentials: 'include',
    body: new URLSearchParams({ 'cookie': document.cookie })
});
</script>

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual changes to the yoobar_message option in the database.
• Look for <script> tags or event handlers in the wp_options table.
• Use Web Application Firewall (WAF) rules to block common XSS patterns in POST requests to admin-ajax.php or plugin settings pages.

Hardening:

• Restrict Contributor-level access to trusted users only.
• Implement Content Security Policy (CSP) headers to block inline scripts.
• Use a WordPress security plugin that monitors file integrity and option changes.

Indicators of Compromise (IOCs)

• File: /wp-content/plugins/yoobar/yoobar.php (check for version 2.0.6)
• Database: wp_options table where option_name = 'yoobar_message' contains <script> tags or base64-encoded JavaScript.
• Network: Outbound requests to attacker-controlled domains from the WordPress admin or frontend.
• Logs: WordPress debug log entries showing unexpected option updates.

Detection Engineering

YARA Rule

rule CVE_2024_11410_YooBar_XSS {
    meta:
        description = "Detects YooBar plugin version 2.0.6 or lower with stored XSS indicators"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-11410"
    strings:
        $vuln_version = "Version: 2.0.6" nocase
        $xss_payload = /<script[^>]*>.*<\/script>/is
        $option_name = "yoobar_message"
    condition:
        $vuln_version and $option_name and $xss_payload
}

Sigma Rule

title: CVE-2024-11410 - Stored XSS in YooBar WordPress Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects stored XSS payloads in YooBar plugin settings
author: Valters IT
date: 2025-04-10
logsource:
    category: application
    product: wordpress
detection:
    selection:
        option_name: "yoobar_message"
        option_value|contains: 
            - "<script"
            - "onerror="
            - "onload="
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in bar content (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-11410 - YooBar Stored XSS Payload"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin.php"; http_uri; content:"yoobar_message"; http_client_body; pcre:"/<script[^>]*>.*<\/script>/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the YooBar plugin until a patched version is released.
2. Review all Contributor-level accounts and remove any that are not essential.
3. Scan the database for existing XSS payloads in the yoobar_message option.

Long-term Fix:

• The vendor (Yoobar) must release version 2.0.7 with proper input sanitization and output escaping.
• Users should update to the latest version as soon as it becomes available.

Workaround:

• Add a custom function to your theme’s functions.php to sanitize the option on output:

  add_filter('option_yoobar_message', 'esc_html');
  

Valters IT
Securing Digital Frontiers