TL;DR
A penetration test (pen test) is a simulated attack on your system by authorized security experts. They try to find and exploit vulnerabilities the way real attackers would. Unlike automated scans, pen tests involve human creativity and can chain multiple issues together. Results include a report of findings with severity ratings and remediation guidance.
The Simple Explanation
You hire security experts to try to break into your app. They use the same techniques real attackers use: finding vulnerabilities, exploiting them, and seeing how far they can get. At the end, they tell you what they found and how to fix it. It is like hiring someone to test your locks by actually trying to pick them.
Types of Pen Tests
| Type | Tester Knowledge | Best For |
|---|---|---|
| Black Box | No prior knowledge | Simulating external attackers |
| White Box | Full access to code | Thorough coverage |
| Gray Box | Partial knowledge | Authenticated user attacks |
What Gets Tested
- Web application: OWASP Top 10, business logic
- API: Authentication, authorization, data exposure
- Network: Firewall rules, open ports, services
- Mobile app: Client-side security, API communication
- Cloud: Configuration, IAM, data storage
Pen Test Phases
- Scoping: Define what to test and rules of engagement
- Reconnaissance: Gather information about the target
- Scanning: Identify potential vulnerabilities
- Exploitation: Attempt to exploit findings
- Post-exploitation: See what access enables
- Reporting: Document findings and recommendations
Get written authorization. Pen testing without permission is illegal hacking. Always have a signed agreement defining scope, timing, and allowed techniques before testing begins.
Pen Test vs Vulnerability Scan
| Aspect | Vulnerability Scan | Penetration Test |
|---|---|---|
| Approach | Automated tools | Human experts |
| Depth | Surface-level | Deep exploitation |
| Frequency | Continuous/weekly | Annual or after changes |
| Cost | Lower | Higher |
What is the difference between a pen test and a vulnerability scan?
A vulnerability scan is automated and identifies potential vulnerabilities. A penetration test involves human experts who actively try to exploit vulnerabilities, chain them together, and demonstrate real impact. Scans find issues; pen tests prove they are exploitable and show what damage is possible.
How often should I do penetration testing?
At minimum, annually. Also test after major changes (new features, infrastructure changes), before launching new products, and as required by compliance (PCI-DSS requires annual pen tests). Continuous testing through bug bounty programs provides ongoing coverage between formal tests.
What is the difference between black box, white box, and gray box testing?
Black box: testers have no prior knowledge, simulating an external attacker. White box: testers have full access to source code and documentation. Gray box: testers have partial knowledge, like user credentials. Each approach has trade-offs between realism and thoroughness.