CVE-2024-44818

Executive Summary

CVE-2024-44818 is a reflected Cross-Site Scripting (XSS) vulnerability in ZZCMS versions 2023 and earlier. The flaw resides in the caina.php component, where the HTTP_Referer header is improperly sanitized before being reflected in the application’s response. An attacker can craft a malicious link that, when clicked by an authenticated or unauthenticated user, executes arbitrary JavaScript in the context of the victim’s browser session. This can lead to session hijacking, credential theft, or defacement. No official patch has been released by the vendor, and no public exploit code or Nuclei template is available at this time.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
• Base Score: 5.4 (Medium)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must click a crafted link)
• Scope: Unchanged
• Confidentiality Impact: Low (potential cookie theft)
• Integrity Impact: Low (potential content injection)
• Availability Impact: None

Threat Level: Medium. The vulnerability requires user interaction but can be exploited without authentication, making it a viable vector for phishing campaigns.

Deep Dive & Mechanics

The vulnerability exists in the caina.php script, which processes the HTTP_Referer header. When a request is made to this endpoint, the application echoes the Referer value directly into the HTML response without proper encoding or sanitization. An attacker can craft a URL that, when visited, sets a malicious Referer header (e.g., via a <meta> refresh or a link with a javascript: URI). The injected payload executes in the victim’s browser, allowing the attacker to steal cookies, perform actions on behalf of the user, or redirect to phishing pages.

Root Cause: Lack of output encoding for user-controllable input (the Referer header) in the response.

Vulnerable vs. Patched Code

Vulnerable Code (zzcms/caina.php):

<?php
$referer = $_SERVER['HTTP_REFERER'];
echo "Referer: " . $referer;
?>

Patched Code (hypothetical):

<?php
$referer = $_SERVER['HTTP_REFERER'];
echo "Referer: " . htmlspecialchars($referer, ENT_QUOTES, 'UTF-8');
?>

The patched version uses htmlspecialchars() to encode special HTML characters, preventing script injection.

Exploitation & Lab Setup

Red Team

Proof-of-Concept (PoC):

1. Host a malicious page that sets a crafted Referer header:

   <html>
   <body>
   <a href="http://target-zzcms/caina.php" referrerpolicy="unsafe-url">Click me</a>
   <script>
   // Alternative: use meta refresh
   // <meta http-equiv="refresh" content="0;url=http://target-zzcms/caina.php">
   </script>
   </body>
   </html>
   

2. Alternatively, use a direct link with a javascript: URI:

   http://target-zzcms/caina.php
   

   Set the Referer header via a custom HTTP client:

   curl -H "Referer: <script>alert('XSS')</script>" http://target-zzcms/caina.php
   

Exploit-DB Code: None available.

Blue Team

Detection Steps:

• Monitor web server logs for unusual Referer headers containing <script>, onerror=, or other JavaScript event handlers.
• Deploy a Web Application Firewall (WAF) rule to block requests with suspicious Referer values.
• Conduct regular code reviews to ensure all user input is properly sanitized.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to /caina.php with Referer headers containing <script>, %3Cscript%3E, or other encoded script tags.
  • Outbound connections from the victim’s browser to attacker-controlled domains (e.g., for cookie exfiltration).
• File IOCs:
  • Modified caina.php file (if attacker gains write access).
  • Suspicious entries in web server access logs (e.g., "Referer: <script>...").

Detection Engineering

YARA Rule

rule CVE_2024_44818_XSS_Referer {
    meta:
        description = "Detects XSS payloads in HTTP Referer header targeting ZZCMS caina.php"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2024-44818"
    strings:
        $xss_payload = /<script[^>]*>.*<\/script>/i
        $event_handler = /on\w+\s*=\s*['"][^'"]*['"]/i
        $encoded_script = /%3Cscript%3E|%3C\/script%3E/i
    condition:
        any of them
}

Sigma Rule

title: Suspicious Referer Header in ZZCMS Request
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects XSS attempts via Referer header in ZZCMS caina.php
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-uri-stem: '/caina.php'
        cs(Referer): '*<script>*'
    condition: selection
falsepositives:
    - Legitimate use of script tags in Referer (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-44818 ZZCMS XSS via Referer Header"; flow:to_server; content:"/caina.php"; http_uri; content:"Referer|3a|"; http_header; pcre:"/<script[^>]*>.*<\/script>/i"; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Apply input validation and output encoding to the Referer header in caina.php. Use htmlspecialchars() or equivalent.
2. WAF Rule: Block requests containing <script> or onerror= in the Referer header.
3. User Education: Train users to avoid clicking suspicious links, especially those that redirect to ZZCMS.
4. Vendor Contact: Reach out to ZZCMS maintainers for an official patch. If none is forthcoming, consider migrating to a supported CMS.
5. Monitoring: Enable detailed logging for /caina.php and alert on anomalous Referer values.

Valters IT
Securing Digital Frontiers