Penetration Testing: Your Own Systems

TL;DR

Learn how to safely test your own systems for weaknesses before attackers do. This guide covers planning, tools, and basic techniques.

1. Planning & Scope

Before you start, it’s vital to plan carefully. You don’t want to accidentally disrupt important services or break the law!

• Define the scope: What systems are you allowed to test? (e.g., a specific web server, your home network). Never test systems you don’t own or have explicit permission to assess.
• Document everything: Keep detailed records of what you do, what tools you use, and any findings. This is crucial for reporting and fixing issues later.
• Backup your data: Before making *any* changes, create backups of all systems involved. This allows you to restore them if something goes wrong.
• Consider the impact: Testing can cause downtime or unexpected behaviour. Schedule tests during off-peak hours whenever possible.

2. Information Gathering (Reconnaissance)

The first step is to gather as much information about your target system as possible.

• Network Scanning: Use tools like nmap to identify open ports and services running on your systems.

  nmap -sV -O <target_IP>

  (-sV for version detection, -O for OS detection – use with caution as it can be noisy).

• Website Analysis: If testing a web application, examine the source code, robots.txt file, and sitemap to understand its structure.
• DNS Enumeration: Find subdomains and other DNS records using tools like dig or online services such as DNSDumpster.

3. Vulnerability Scanning

Automated vulnerability scanners can identify common weaknesses.

• Nessus: A popular commercial scanner with a free ‘Home’ version for personal use.
• OpenVAS: An open-source alternative to Nessus. Requires more setup but is very powerful.
• Nikto: Specifically designed for web server scanning, identifying outdated software and potential vulnerabilities.

  nikto -h <target_IP>

Important: Vulnerability scanners often produce false positives. Always manually verify the findings.

4. Exploitation (Basic Techniques)

This is where you attempt to exploit identified vulnerabilities. Start with simple techniques and always be careful!

• Password Attacks: Try common passwords or use password cracking tools like John the Ripper or Hashcat against password hashes (if obtained).
• SQL Injection: If testing a web application, try injecting SQL code into input fields to bypass security measures. Be extremely careful with this as it can damage your database.

  ' OR '1'='1

• Cross-Site Scripting (XSS): Inject malicious JavaScript code into web pages to steal cookies or redirect users.
• Exploit Databases: Search for known exploits on websites like Exploit Database based on the software versions identified during reconnaissance.

5. Post-Exploitation

Once you’ve gained access to a system, what can you do?

• Privilege Escalation: Attempt to gain higher levels of access (e.g., from user to administrator).
• Data Exfiltration: Simulate stealing sensitive data to assess the impact of a successful attack.
• Persistence: Try to establish a persistent presence on the system so you can regain access later.

6. Reporting & Remediation

Document your findings in a clear and concise report.

• Executive Summary: A high-level overview of the vulnerabilities found and their potential impact.
• Technical Details: Detailed information about each vulnerability, including steps to reproduce it.
• Remediation Recommendations: Specific actions to fix the vulnerabilities (e.g., patching software, changing passwords, implementing security controls).