Security Testing Fundamentals
Finding security vulnerabilities in your own code is far better than having attackers find them for you. Security testing uses multiple approaches because no single method catches everything.
Types of Security Testing
Static Application Security Testing (SAST) analyzes your source code without running it. These tools scan for patterns that indicate vulnerabilities — like SQL queries built from user input or hardcoded credentials. SAST catches issues early but can produce false positives and misses runtime-only problems.
Dynamic Application Security Testing (DAST) tests your running application from the outside, like an attacker would. It sends malicious inputs and observes responses, finding issues like cross-site scripting or SQL injection that only appear at runtime.
Interactive Application Security Testing (IAST) combines both approaches by instrumenting your application during testing. It sees both the code and runtime behavior, reducing false positives while catching more issues.
Penetration testing involves skilled testers simulating real attacks. They think creatively, chain vulnerabilities together, and find issues automated tools miss.
Common Security Testing Tools
For static analysis, language-specific tools work best:
# Python - Bandit finds common security issues
bandit -r src/
# JavaScript - ESLint with security plugins
npm install eslint-plugin-security
eslint --ext .js src/
OWASP ZAP is a free, powerful web application scanner for dynamic testing. It crawls your application and tests for common vulnerabilities automatically.
Dependency scanners check your packages for known vulnerabilities:
# npm projects
npm audit
# Python projects
pip-audit
When to Test
Integrate security testing throughout your development process:
Every commit should trigger automated SAST scans. These are fast and catch obvious issues immediately.
Every pull request should include dependency scanning. New packages or updates might introduce vulnerabilities.
Regular intervals — weekly or monthly — run DAST scans against staging environments. These take longer but find different issues.
Before major releases, consider professional penetration testing. Fresh eyes and expert knowledge find what automation misses.
Handling Results
Not every finding requires immediate action. Prioritize by severity and exploitability. Critical vulnerabilities in production code need immediate fixes. Low-severity issues in internal tools can wait for the backlog.
Document why you're accepting certain risks. "We acknowledge this theoretical vulnerability but mitigate it through network controls" is better than ignoring findings entirely.