Comparison Guide

SAST vs DAST

Static vs Dynamic Application Security Testing: understand the differences, know when to use each, and learn how to combine them for comprehensive security coverage.

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Quick Comparison

SAST

Analyzes source code without running the application

"What vulnerabilities exist in my code?"

DAST

Tests the running application from the outside

"What can attackers exploit right now?"

Detailed Comparison

AspectSASTDAST
Testing TypeWhite-box (inside-out)Black-box (outside-in)
Input RequiredSource codeRunning application URL
When in SDLCDevelopment (early)Testing/Production (late)
CoverageAll code pathsOnly discoverable endpoints
False PositivesHigherLower
Remediation InfoExact line numberURL/endpoint only
Language SupportMust support languageAny technology
Runtime IssuesCan't detectDetects
Business LogicCan't understandLimited understanding
Scan SpeedFast (minutes)Slower (hours)

What Each Approach Finds Best

SAST Excels At

  • Hardcoded secrets and credentials
  • SQL injection patterns in code
  • Buffer overflows and memory issues
  • Insecure cryptographic implementations
  • Code quality and maintainability issues
  • Vulnerable dependency versions

DAST Excels At

  • Authentication and session issues
  • Server misconfigurations
  • Missing security headers
  • SSL/TLS vulnerabilities
  • CORS and CSRF issues in practice
  • Runtime injection exploitability

When to Use Each

Use SAST When...

  • • On every commit via CI/CD pipeline
  • • During code review before merge
  • • When you need to find the exact vulnerable code line
  • • Checking for hardcoded secrets before commit
  • • Auditing code quality and security patterns

Use DAST When...

  • • After deploying to staging/production
  • • Validating security configurations
  • • Testing third-party integrations
  • • Verifying SAST findings are exploitable
  • • Compliance testing (PCI DSS, etc.)

Use Both Together...

  • • For comprehensive security coverage
  • • When security is critical (fintech, healthcare)
  • • In mature DevSecOps pipelines
  • • Before major releases

The Best Approach: Use Both

SAST and DAST are complementary, not competing approaches. Together they provide defense in depth:

1
SAST during development → Catch issues early, fix cheaply
2
DAST after deployment → Verify real-world security
3
Correlate findings → Prioritize what DAST confirms

Coverage improves dramatically: Studies show SAST finds 40-60% of vulnerabilities, DAST finds 30-50%, but together they can catch 80-90% of common vulnerabilities.

Frequently Asked Questions

If I can only choose one, which should I pick?

For early-stage startups: start with SAST in CI/CD—it's cheaper to fix issues in code than production. Add DAST once you have a live application. If you're already in production with security concerns, start with DAST to find exploitable issues immediately.

Do SAST and DAST replace penetration testing?

No. Automated tools find common vulnerability patterns. Pentesting adds human creativity to find business logic issues, complex attack chains, and novel vulnerabilities that automated tools miss. Use all three for best coverage.

How do I handle the false positives from SAST?

1) Configure rules to match your codebase, 2) Suppress known false positives, 3) Use DAST to verify if SAST findings are exploitable, 4) Prioritize findings in security-critical code paths first.

What about IAST (Interactive AST)?

IAST combines SAST and DAST by instrumenting the running application. It provides code-level detail with runtime confirmation. Consider IAST if you need the best of both worlds and can support the instrumentation overhead.

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Related Resources

What is SAST?What is DAST?Startup Security ChecklistAI Code Security

Last updated: January 2025