In today’s DevSecOps-driven environments, integrating security into every phase of the software development lifecycle is crucial. Two core methodologies widely used in application security testing are Static Application Security Testing (SAST) and Dynamic Application Security Testing (DAST).
Both SAST and DAST are important but work in different ways — SAST checks the code itself, while DAST tests the app while it’s running. Knowing what each one is good at, where it falls short, and when to use them helps QA and security teams keep applications safer.
What is SAST (Static Application Security Testing)?
SAST is a white-box testing approach that analyzes source code, bytecode, or binaries before the application runs. It helps identify flaws at the code level before the app is even deployed.
It detects issues like hardcoded credentials, poor input validation, and weak APIs early in the SDLC. These tools are often language-specific and integrate directly into IDEs or CI pipelines.
Common SAST Tools:
- SonarQube
- Fortify Static Code Analyzer
- Checkmarx
- Veracode (SAST module)
What is DAST (Dynamic Application Security Testing)?
DAST is a black-box testing technique that evaluates an application in its running state. It simulates real-world attacks to expose runtime vulnerabilities like injection flaws or broken authentication.
It’s especially valuable in staging and QA environments to test the entire application stack, including integrated APIs and frontends.
Common DAST Tools:
- OWASP ZAP
- Burp Suite
- Netsparker
- Acunetix
SAST vs DAST: Comparison Table
| Feature | SAST | DAST |
|---|---|---|
| Code Access | Requires source code | No source code access (black-box) |
| Testing Phase | Early in SDLC (pre-build) | Post-deployment (runtime) |
| Vulnerability Detection | Code-level issues | Runtime issues, misconfigurations |
| Test Speed | Fast once integrated | Slower due to interaction |
| Language Dependency | Yes | No |
| False Positives | Higher (static analysis) | Lower (validated behavior) |
| Dev Integration | IDEs, pipelines | Staging & QA environments |
When to Use SAST
SAST is best used during the early development phases, especially during code reviews and build time. It helps enforce secure coding standards and prevents vulnerabilities before they reach staging. Developers and DevSecOps engineers should integrate it into CI pipelines for shift-left testing.
When to Use DAST
DAST is effective for full-stack evaluation just before production. It helps test user workflows, integrated APIs, and staging environments. Security analysts and penetration testers often rely on DAST for real-world attack simulation.
Why Combine SAST and DAST? (Hybrid Approach)
A hybrid strategy combining both methods ensures complete coverage. SAST identifies code flaws, while DAST catches runtime issues like logic flaws or server misconfigurations.
Together, they offer full-spectrum protection from development through deployment. This approach is essential for fintech, healthcare, SaaS, and other industries requiring deep-risk coverage.
Real-World Implementation: Fintech SaaS Security Testing
A fintech company using Node.js and React implemented SAST with SonarQube for early development checks. Burp Suite was integrated into their staging phase for DAST. The result? A 65% reduction in production vulnerabilities and faster issue resolution.
XSS flaws were caught in staging that weren’t detectable through static code scans alone.
Frequently Asked Questions
Q: Can SAST and DAST be used together in DevOps pipelines?
Yes. SAST fits in the build stage, while DAST works during pre-release or staging.
Q: Which is more important — SAST or DAST?
Both. SAST prevents issues early, DAST uncovers runtime problems.
Q: Do SAST tools support open-source projects?
Yes. Tools like SonarQube offer free, community-supported versions.
✅ Conclusion
Choosing between SAST and DAST isn’t a matter of preference — it’s about aligning the right tools with the right stages of your software lifecycle. When used together, these methodologies form a robust defence against vulnerabilities that threaten application integrity and data security.
At Testriq QA Lab LLP, we offer end-to-end application security testing solutions leveraging both SAST and DAST to secure codebases, runtime environments, and everything in between.