CVE-2024-6076

Executive Summary

CVE-2024-6076 is a Reflected Cross-Site Scripting (XSS) vulnerability identified in the WordPress plugin wp-cart-for-digital-products (versions prior to 8.5.5). The plugin fails to properly sanitize and escape a parameter before reflecting it back in the page, allowing an attacker to inject arbitrary JavaScript. This flaw is particularly dangerous because it can be leveraged against high-privilege users, such as administrators, potentially leading to session hijacking, credential theft, or full site compromise. The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation) and is mapped to MITRE ATT&CK tactic T1190 (Exploit Public-Facing Application). No public proof-of-concept (PoC) or exploit code is currently available, but the risk remains significant due to the widespread use of WordPress plugins.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed through the official WordPress plugin repository. Users who installed the plugin via the WordPress dashboard or manually are at risk. The supply chain risk is moderate, as the plugin is not a core dependency but is widely used for e-commerce functionality. Organizations should verify their plugin version and update immediately to version 8.5.5 or later.

CVSS Breakdown & Threat Level

• CVSS Score: 6.1 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must click a crafted link)
• Scope: Changed
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

Threat Level: Medium. The vulnerability requires user interaction but can be exploited against high-privilege users, increasing the potential impact.

Deep Dive & Mechanics

The vulnerability resides in the wp-cart-for-digital-products plugin, which handles digital product sales. A specific parameter (likely wp_cart_display or similar) is not sanitized or escaped before being output in the HTML response. An attacker can craft a malicious URL containing JavaScript payloads in this parameter. When a victim (especially an admin) clicks the link, the script executes in the context of the WordPress admin dashboard, allowing actions such as creating new admin users, modifying site settings, or injecting backdoors.

The root cause is the use of echo $_GET['param'] or similar without proper validation. The plugin likely uses esc_html() or esc_attr() only partially, leaving the parameter vulnerable.

Vulnerable vs. Patched Code

Vulnerable Code (pre-8.5.5):

// Example vulnerable snippet
$display = $_GET['wp_cart_display'];
echo "<div class='wp-cart-display'>" . $display . "</div>";

Patched Code (8.5.5+):

// Patched snippet using esc_html()
$display = isset($_GET['wp_cart_display']) ? esc_html($_GET['wp_cart_display']) : '';
echo "<div class='wp-cart-display'>" . $display . "</div>";

The patch applies esc_html() to the parameter, converting special characters to HTML entities and preventing script injection.

Exploitation & Lab Setup

Red Team (Exploitation)

1. Setup: Install WordPress with wp-cart-for-digital-products version 8.5.4 or earlier.
2. Craft Payload: Create a URL with a malicious JavaScript payload in the vulnerable parameter.

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

3. Deliver: Send the link to a logged-in admin via email, social engineering, or other means.
4. Execute: When the admin clicks the link, the script executes in their browser session.

Advanced Payload Example:

http://target-site.com/?wp_cart_display=<script>fetch('/wp-admin/admin-ajax.php?action=create_admin&username=hacker&password=evilpass')</script>

Blue Team (Detection & Prevention)

1. Monitor Logs: Look for unusual URL parameters containing <script> or onerror patterns.
2. WAF Rules: Deploy Web Application Firewall rules to block reflected XSS attempts.
3. User Training: Educate admins about phishing links and the risks of clicking untrusted URLs.
4. Update: Immediately upgrade to version 8.5.5 or later.

Indicators of Compromise (IOCs)

• URL Patterns: Requests containing wp_cart_display= followed by <script> or onerror attributes.
• Log Entries: HTTP 200 responses with injected JavaScript in the response body.
• File Changes: Unexpected modifications to WordPress core files or plugin files.
• User Accounts: Creation of new admin users without proper authorization.

Detection Engineering

YARA Rule

rule wp_cart_xss_detect {
    meta:
        description = "Detects reflected XSS attempts against wp-cart-for-digital-products"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-6076"
    strings:
        $param = "wp_cart_display="
        $script = /<script[^>]*>.*<\/script>/i
        $event = /on\w+\s*=\s*['"][^'"]*['"]/i
    condition:
        $param and ($script or $event)
}

Sigma Rule

title: Reflected XSS Attempt Against wp-cart-for-digital-products
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects HTTP requests with malicious payloads targeting the wp_cart_display parameter
author: Valters IT
date: 2024-01-01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains: "wp_cart_display="
        c-uri|contains|any:
            - "<script"
            - "onerror"
            - "onload"
    condition: selection
falsepositives:
    - Legitimate use of the parameter with safe content
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-6076 Reflected XSS in wp-cart-for-digital-products"; flow:to_server,established; content:"wp_cart_display="; http_uri; pcre:"/<script[^>]*>.*<\/script>/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Upgrade the plugin to version 8.5.5 or later from the WordPress plugin repository.
2. Virtual Patching: If immediate upgrade is not possible, deploy a WAF rule to block requests containing wp_cart_display= with script tags.
3. Code Review: Audit all custom WordPress plugins for similar input sanitization issues.
4. User Awareness: Train administrators to avoid clicking suspicious links, especially when logged into WordPress.
5. Monitoring: Enable logging for all admin actions and review for anomalies.

Valters IT - DevSecOps & Cyber Threat Intelligence