Penetration testing is the practice of testing a computer system, network, or web application to find security vulnerabilities that an attacker could exploit.
What is Penetration Testing?
Penetration testing (pen testing) simulates real-world attacks against your systems to identify weaknesses before malicious hackers do. It's a critical component of any security program.
The Penetration Testing Methodology
Phase 1: Planning and Reconnaissance
Define the scope and goals of the test. Gather intelligence (OSINT) about the target—domain names, IP ranges, employee information, technology stack.
Key tools: Nmap, Shodan, theHarvester, Maltego, Google Dorks
Phase 2: Scanning
Use automated tools to understand how the target responds to various intrusion attempts. Port scanning, vulnerability scanning, and service enumeration reveal the attack surface.
Key tools: Nessus, OpenVAS, Nikto, Burp Suite
Phase 3: Gaining Access
Attempt to exploit identified vulnerabilities. This may involve web application attacks (SQL injection, XSS), network attacks (password cracking, man-in-the-middle), or social engineering.
Key tools: Metasploit, SQLmap, Hydra, John the Ripper
Phase 4: Maintaining Access
Determine if the vulnerability can be used to achieve persistent presence in the system. This simulates advanced persistent threats (APTs).
Phase 5: Reporting
Document findings including vulnerabilities discovered, data accessed, time spent undetected, and remediation recommendations. A good report is the most valuable deliverable of a pen test.
Types of Penetration Tests
- Black Box: No prior knowledge of the target system
- White Box: Full knowledge of the system, including source code
- Gray Box: Partial knowledge, simulating an insider or compromised user
Legal and Ethical Considerations
Always obtain written authorization before testing. Stay within the agreed scope. Follow responsible disclosure practices. Never test systems you don't have permission to test.
Getting Started
- Learn networking fundamentals (TCP/IP, DNS, HTTP)
- Practice on legal platforms (HackTheBox, TryHackMe, DVWA)
- Study for certifications (CEH, OSCP, PNPT)
- Build a home lab for practicing
- Join the community (bug bounty programs, CTF competitions)