Dynamic Analysis (DAST)

What is DAST?

DAST is a complement to SAST, not a replacement

SAST looks at the code and DAST looks at the running app. The two must be applied together to reduce blind spots.

Definition: DAST sends real HTTP requests to a running application to detect runtime vulnerabilities such as SQL injection, XSS, authentication bypass, and sensitive information disclosure.

How it differs from SAST: SAST scans quickly during the coding phase but cannot observe runtime behavior. DAST verifies actual behavior after deployment, helping you find vulnerabilities that SAST misses.

---

Tool Comparison

Tool	Features	Main uses	License
OWASP ZAP	Industry-standard, GUI and automation support	Full scan of web apps/APIs	Apache-2.0
Nuclei	Template-based, fast, lightweight	Scanning for known vulnerability patterns	MIT

We recommend OWASP ZAP for in-depth web application scanning, and Nuclei for quick checks of known CVEs and misconfigurations.

---

OWASP ZAP setup

GitHub Actions

YAML

# .github/workflows/dast-zap.yml

name: DAST — OWASP ZAP

on:
  push:
    branches: [main]

jobs:
  zap:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      # run app (e.g., Docker Compose)
      - name: Start application
        run: |
          docker compose up -d
          sleep 10  # wait for app startup

      # ZAP Baseline scan (baseline vulnerability detection without manual intervention)
      - name: ZAP Baseline Scan
        uses: zaproxy/action-baseline@v0.12.0
        with:
          target: http://localhost:8080
          rules_file_name: zap-rules.tsv
          fail_action: true

      # ZAP API scan (based on OpenAPI spec)
      - name: ZAP API Scan
        uses: zaproxy/action-api-scan@v0.7.0
        with:
          target: http://localhost:8080/api/openapi.json
          format: openapi
          fail_action: true

      - name: Upload ZAP report
        uses: actions/upload-artifact@v4
        if: always()
        with:
          name: zap-report
          path: report_html.html

Select scan type

Scan Type	Action	Time required	Recommended situation
Baseline	action-baseline	2~5 minutes	Basic check per PR
API Scan	action-api-scan	5~15 minutes	When an OpenAPI specification exists
Full Scan	action-full-scan	20 minutes+	In-depth pre-release check

We recommend a two-tier strategy: run Baseline during the PR phase and Full Scan before release.

Rules file configuration

Rules that ignore or fail specific alerts are managed in the zap-rules.tsv file.

# zap-rules.tsv
10016	IGNORE	(Browser XSS protection header — legacy browser support not required)
10020	WARN	(X-Frame-Options header not set)
10021	FAIL	(Anti-CSRF token not set)

You can set the handling for each item at three levels: IGNORE·WARN·FAIL.

---

Nuclei setup

GitHub Actions

YAML

# .github/workflows/dast-nuclei.yml

name: DAST — Nuclei

on:
  push:
    branches: [main]

jobs:
  nuclei:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Start application
        run: |
          docker compose up -d
          sleep 10

      - name: Run Nuclei
        uses: projectdiscovery/nuclei-action@main
        with:
          target: http://localhost:8080
          templates: cves,misconfiguration,exposures
          severity: medium,high,critical
          fail-on-severity: high

      - name: Upload Nuclei report
        uses: actions/upload-artifact@v4
        if: always()
        with:
          name: nuclei-report
          path: nuclei.log

Main template categories

Category	Description
cves	Known CVE vulnerability patterns
misconfiguration	Security misconfigurations
exposures	Sensitive information/file exposure
default-logins	Default accounts/passwords
takeovers	Potential subdomain takeover

---

Precautions when adopting DAST

Always run DAST in an isolated test environment.

Environment separation: Because DAST sends real HTTP requests, running it against production can corrupt data and disrupt service. Always run it only in a staging or test environment.

Authentication setup: For endpoints that require authentication, pass a token through ZAP's authentication settings or Nuclei's header option to ensure full coverage.

False positive management: DAST has a higher false positive rate than SAST. We recommend a phased approach: start with WARN and switch to FAIL after reviewing the results.

---

Next steps

• Full security pipeline integration: Pipeline Design
• Continuous security monitoring after deployment: Monitoring and Automated Remediation