Penetration Testing Concepts
Penetration testing — or "pen testing" — involves security professionals attempting to breach your systems with your permission. Unlike automated scanners, pen testers think creatively, chain vulnerabilities together, and simulate how real attackers operate.
Types of Penetration Tests
The amount of information testers receive affects what they find:
Black box testing gives testers no prior knowledge. They start like external attackers, discovering your systems through reconnaissance. This tests your external attack surface realistically but may miss internal vulnerabilities.
White box testing provides full access: source code, architecture diagrams, credentials. Testers can examine everything, finding deeper issues. This is thorough but doesn't simulate external attackers.
Gray box testing offers partial information — perhaps user-level credentials or basic architecture knowledge. This balances realism with depth, simulating attackers who've gained initial access.
The Penetration Testing Methodology
Professional pen testers follow structured approaches:
Reconnaissance gathers information about your systems. What domains do you own? What technologies do you use? What's publicly exposed? Much of this comes from public sources.
Scanning identifies potential entry points. Port scans reveal running services. Vulnerability scanners check for known issues. Web crawlers map application functionality.
Exploitation attempts to leverage discovered weaknesses. Can that outdated service be compromised? Does that input field allow SQL injection? Testers try to gain unauthorized access.
Post-exploitation assesses impact after initial access. Can they reach sensitive data? Escalate privileges? Move to other systems? This reveals how bad a breach could get.
Reporting documents everything: what was found, how it was exploited, and how to fix it. Good reports include severity ratings, reproduction steps, and remediation guidance.
When to Engage Pen Testers
Before major launches — new applications or significant features deserve security review before users encounter them.
After significant changes — major refactors, new integrations, or architecture changes can introduce vulnerabilities.
Annually at minimum — even stable systems need regular review as new attack techniques emerge.
For compliance — many regulations require periodic penetration testing.
DIY vs Professional Testing
Basic security testing is accessible to developers. Tools like OWASP ZAP can scan your applications automatically. Burp Suite enables manual testing of web applications.
However, professional pen testers bring expertise you can't easily replicate: years of experience, knowledge of obscure attack techniques, and fresh perspectives on systems you're too familiar with. For critical systems, professional testing is worth the investment.