Join our Newsletter — 33% off our NHI Course

Static and Dynamic Application Security Testing (SAST/DAST)

Static and dynamic application security testing are two methods for finding flaws in software. Static testing examines source code, bytecode, or binaries without running the application, while dynamic testing probes a live application from the outside to find runtime weaknesses such as injection, authentication and session handling issues.

How SAST and DAST differ

static application security testing inspects code, bytecode, or binaries without execution, so it is strongest for finding flaws before release. dynamic application security testing exercises a running application from the outside, so it is strongest for exposing runtime weaknesses that only appear in execution.

The practical difference is where each method sits in the delivery lifecycle and what it can observe. SAST can surface insecure coding patterns early, while DAST can confirm whether controls actually hold in a deployed or test environment.

What each method is best at finding

SAST is well suited to logic errors, insecure API usage, tainted data flows, and code-level weaknesses that can be spotted by analysing source or compiled artefacts. DAST is better at issues that depend on a live system, including injection paths, broken authentication behaviour, session handling flaws, and misconfigurations visible through the application interface.

Neither method is complete on its own. SAST may miss runtime-only behaviour, while DAST may miss dormant code paths, unreachable conditions, and weaknesses buried in libraries or branches that are not exercised during a scan.

That is why many programmes treat them as complementary controls rather than substitutes, and why testing guidance usually pairs them with manual review for business logic, privilege boundaries, and edge cases. OWASP ASVS is a useful external benchmark for deciding which classes of weakness each test method should help verify.

How organisations use SAST and DAST in practice

Most teams place SAST earlier in the delivery pipeline, where it can run on every commit or build and provide fast feedback to developers. DAST is usually run later, against a deployed test environment or staging release, where authenticated scanning, test data, and environment stability become important.

For application teams, the question is not which technique is “better” but which failure modes each one can reliably catch in the organisation’s context. A mature programme uses SAST to shift discovery left and DAST to validate exposed behaviour after integration, deployment, or major change.

When teams need a practical operating model for combining the two, NHIMG’s Application Security Guide explains how SAST, DAST, IAST, SCA, triage, and release gating fit into a broader application security programme. For tool selection, the Application Security Testing Buyer’s Guide helps compare SAST and DAST capabilities without confusing coverage claims with actual assurance.

Limits, tuning, and common misunderstandings

SAST often generates false positives when code patterns look risky but are contextually safe, and it can also miss issues introduced by deployment configuration, external integrations, or runtime state. DAST can miss vulnerabilities if the scanner lacks authentication, crawl coverage, realistic test data, or time to exercise the right application states.

A common misunderstanding is to treat scan output as equivalent to assurance. In reality, the value comes from matching the technique to the weakness class, tuning it to the application, and feeding results into secure coding and remediation workflows. That is why web testing guidance such as the Web Application Security Testing Guide remains relevant alongside automated scanners.

For teams that want a DAST-specific operational reference, the OWASP ZAP Guide shows how baseline, authenticated, API, and CI/CD scans translate into real web application testing work.

Standards & Framework Alignment

This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.

OWASP ASVS provides the primary governance reference for this term.

Framework Control / Reference Relevance
OWASP ASVS V6 — Authentication SAST/DAST often verify auth weaknesses and session flaws in applications.
V7 — Session Management DAST commonly reveals session handling failures in running applications.
V8 — Authorization Application testing must validate access-control logic that static and dynamic tests can both expose.
Recommendation — Use V6 to verify authentication behaviour and catch weaknesses scanners should expose. Use V7 to test session controls in the live app and confirm they hold under attack-like traffic. Use V8 to verify access decisions and detect broken authorization paths during testing.