CVE-2024-25637

Executive Summary

CVE-2024-25637 is a reflected Cross-Site Scripting (XSS) vulnerability in October CMS, a self-hosted platform built on Laravel. The flaw resides in the X-October-Request-Handler header, which fails to sanitize the AJAX handler name, allowing unescaped HTML to be reflected back to the user. The CVSS score is 3.1 (Low), and the EPSS probability is 0.0%, indicating a very low likelihood of exploitation in the wild. The vulnerability is considered non-exploitable through normal browser interactions and is only detectable via proxy interception tools. The issue has been patched in version 3.5.15.

Supply Chain & Package Security

October CMS is a PHP-based CMS distributed via Composer. The vulnerability does not directly affect the supply chain, but users should ensure they are using the latest patched version (3.5.15) to avoid potential exploitation in automated or proxy-based scenarios.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
• Base Score: 3.1 (Low)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: None (C:N)
• Integrity Impact: Low (I:L)
• Availability Impact: None (A:N)

The low score reflects the limited impact and the requirement for a proxy interception tool to trigger the reflection. The vulnerability does not allow direct exploitation via standard browser interactions.

Deep Dive & Mechanics

The vulnerability exists in the handling of the X-October-Request-Handler HTTP header. When an AJAX request is made to October CMS, the handler name from this header is reflected back in the response without proper HTML encoding. This allows an attacker to inject arbitrary HTML or JavaScript into the response.

Root Cause: The lack of output sanitization on the handler name before reflection.

Attack Vector: An attacker must intercept or craft HTTP requests with a malicious X-October-Request-Handler header. The reflected payload is only visible in the raw HTTP response, not in the browser's DOM, making it non-exploitable via standard user interactions.

Impact: Low integrity impact. An attacker could potentially craft a response that, when viewed through a proxy or automated tool, could mislead or cause minor harm, but no direct user compromise is possible.

Vulnerable vs. Patched Code

Vulnerable Code (before 3.5.15):

// In the AJAX handler processing
$handler = $request->header('X-October-Request-Handler');
// Direct reflection without sanitization
return response()->json(['handler' => $handler]);

Patched Code (3.5.15):

// In the AJAX handler processing
$handler = $request->header('X-October-Request-Handler');
// Sanitize the handler name
$handler = e($handler); // Laravel's e() function for HTML escaping
return response()->json(['handler' => $handler]);

The patch uses Laravel's e() helper to HTML-encode the handler name before reflection, preventing XSS.

Exploitation & Lab Setup

Red Team

Prerequisites:

• October CMS version < 3.5.15
• Ability to send custom HTTP requests (e.g., using Burp Suite, cURL, or Postman)

Exploitation Steps:

1. Identify a target running October CMS.
2. Send a crafted HTTP request with a malicious X-October-Request-Handler header:

   GET / HTTP/1.1
   Host: target.com
   X-October-Request-Handler: <script>alert('XSS')</script>
   

3. Observe the reflected payload in the response body:

   {"handler":"<script>alert('XSS')</script>"}
   

Note: This exploit is only detectable via proxy interception tools and does not execute in a standard browser context.

Blue Team

Detection:

• Monitor for unusual X-October-Request-Handler headers containing HTML tags or JavaScript.
• Use the provided Sigma and Suricata rules to detect exploitation attempts.

Mitigation:

• Upgrade to October CMS version 3.5.15 or later.
• Implement Web Application Firewall (WAF) rules to block suspicious headers.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP requests with X-October-Request-Handler header containing HTML tags (e.g., <script>, <img>, <svg>)
  • Response bodies containing unescaped HTML in the handler field

• File IOCs:

  • Log entries showing requests with suspicious X-October-Request-Handler values

• Behavioral IOCs:

  • Automated scanning tools probing for reflected XSS in AJAX handlers

Detection Engineering

YARA Rule

rule CVE_2024_25637_October_XSS {
    meta:
        description = "Detects reflected XSS in October CMS via X-October-Request-Handler header"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-25637"
    strings:
        $header = "X-October-Request-Handler"
        $xss_pattern = /<[^>]+>/
    condition:
        $header and $xss_pattern
}

Sigma Rule

title: CVE-2024-25637 - Reflected XSS in October CMS
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects exploitation attempts of CVE-2024-25637 via X-October-Request-Handler header
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query: '*'
        cs-headers: 'X-October-Request-Handler*'
        cs-headers|contains: '<'
    condition: selection
falsepositives:
    - Legitimate use of HTML in handler names (unlikely)
level: low

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-25637 - October CMS Reflected XSS"; flow:to_server,established; content:"X-October-Request-Handler"; http_header; pcre:"/<[^>]+>/"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade October CMS to version 3.5.15 or later.
2. If upgrade is not possible, implement a WAF rule to block requests containing HTML tags in the X-October-Request-Handler header.

Long-term Measures:

• Regularly update October CMS and all dependencies.
• Conduct security audits of custom AJAX handlers.
• Implement Content Security Policy (CSP) headers to mitigate XSS impact.

Workarounds:

• Disable AJAX handler reflection if not required.
• Use input validation to reject handler names containing special characters.

Valters IT
DevSecOps & Cyber Threat Intelligence