Penetration testing (pen testing) is a controlled, authorized attack against your systems conducted by security professionals to find exploitable vulnerabilities before real attackers do. Unlike automated scanning, pen testing involves human expertise to chain together weaknesses, test business logic, and simulate realistic attack scenarios against your applications, infrastructure, and processes.
Penetration testing, commonly called pen testing, is a security assessment where skilled professionals attempt to exploit vulnerabilities in your systems using the same techniques real attackers employ. The goal is to find weaknesses that automated tools miss by applying human creativity, contextual understanding, and the ability to chain together multiple low-severity issues into a significant compromise.
A pen test typically follows a structured methodology:
Pen tests come in several varieties: external (testing internet-facing assets), internal (simulating an insider or someone who's breached the perimeter), web application (focused on a specific app or API), social engineering (testing human vulnerabilities like phishing), and red team (a broader, adversarial simulation of a real-world attack campaign).
For startups, the question isn't whether you need pen testing, but when and how often.
Here's why it matters:
Fencer and pen testing serve different but complementary purposes. Fencer provides continuous, automated security monitoring. Pen testing provides periodic, human-driven security assessment. Together, they give you both breadth and depth.
How they work together:
A vulnerability scan is an automated process that checks your systems against a database of known vulnerabilities. It's fast, repeatable, and covers a broad surface, but it only identifies potential issues without verifying them. A penetration test is a manual, expert-driven assessment where a security professional actively tries to exploit vulnerabilities, chain them together, and demonstrate real-world impact. Vulnerability scans tell you what might be wrong. Pen tests prove what's actually exploitable and how far an attacker could get.
At minimum, once per year for compliance purposes (SOC 2, PCI DSS). Beyond that, schedule additional pen tests after major product releases, significant infrastructure changes, or before launching a new product. Many startups adopt a hybrid model: annual comprehensive pen tests supplemented by continuous automated scanning (SAST, DAST, CSPM) to catch issues between tests. As your product matures and your customer base grows, increasing to semi-annual testing is common.
Start with external pen testing, which evaluates your internet-facing attack surface (web applications, APIs, cloud infrastructure). This is where most attacks originate and what compliance frameworks prioritize. Internal pen testing (simulating an insider threat or a post-breach scenario) becomes important as your team grows and your infrastructure becomes more complex. For most early-stage startups, an external web application and cloud infrastructure pen test provides the highest return on investment.