SAST vs DAST vs SCA: A Developer's Guide
SAST, DAST and SCA each test a different layer of application security. Here's how to combine them into an actual testing program, not just three separate tools.
Once a team has moved past ad hoc security testing, the next question is usually which combination of tools to actually adopt. SAST, DAST and SCA come up constantly in that conversation, often presented as competing choices. They're not competing — each covers a distinct layer, and a mature testing program typically uses all three together.
The three, briefly
SAST (Static Application Security Testing) analyzes your own source code without running it, catching insecure patterns and hardcoded secrets early, ideally before code merges.
DAST (Dynamic Application Security Testing) tests a running application from the outside, the way an attacker would, catching runtime and configuration issues that only appear once the application is actually deployed.
SCA (Software Composition Analysis) — also called dependency scanning — checks third-party libraries and packages against known-vulnerability databases, covering the code your team didn't write but ships anyway.
What each one actually covers
| SAST | DAST | SCA | |
|---|---|---|---|
| Analyzes | Your source code | Running application | Third-party dependencies |
| Catches | Insecure coding patterns, hardcoded secrets | Runtime/config issues, injection, auth flaws | Known-CVE vulnerable libraries |
| Runs against | Code, pre-execution | Deployed, running app | Dependency manifest/tree |
| Best integration point | CI, pre-merge | Staging/production, scheduled | CI, continuous |
Why one alone leaves a gap
Consider a vulnerability caused by an outdated library with a known CVE. SAST won't catch it — it's not a pattern in your own code. DAST might catch it if the vulnerable behavior is externally observable, but might miss it if the vulnerable function isn't triggered through normal application traffic. SCA catches it directly, because it's checking the dependency itself against known issues.
Now consider a hardcoded API key in your own code. SCA won't see it — it's not a dependency issue. DAST might not catch it unless the key is somehow exposed through application behavior. SAST catches it directly, because it's designed to flag exactly that pattern in source code.
Each tool has a lane. Relying on just one leaves the other two lanes uncovered.
What none of the three catches well
All three are automated and pattern- or database-driven. None of them reliably catches business logic flaws or access control issues — problems that require understanding what the application is supposed to do, not just matching a known pattern. That's the layer that still needs manual or expert testing, regardless of how complete the automated stack is.
Building a combined workflow
A practical setup looks like:
- SAST in CI, running on every pull request, catching insecure patterns before merge
- SCA continuously, checking dependencies on every build and on a recurring schedule, since new CVEs are disclosed independent of your own code changes
- DAST against staging, run on a regular schedule or before major releases, testing the actual running application
- Manual testing periodically, focused specifically on access control and business logic — the layer none of the automated tools reliably cover
Avoiding tool sprawl
It's possible to over-invest in tooling without improving actual security posture — three overlapping scanners generating triplicate alerts that nobody triages is worse than one well-configured tool per layer, properly integrated into the workflow and actually acted on. The goal is coverage across the three layers, not maximum tool count.
How does Averto fit in?
Averto's platform is built to cover the layers that automated tooling alone tends to leave gaps in — particularly the dynamic, runtime layer and the access-control and logic issues neither SAST, DAST nor SCA reliably catch — combined with continuous coverage so findings stay current as the application changes.
Frequently asked questions
Do small teams need all three — SAST, DAST and SCA?
Ideally yes, though the starting priority often depends on the application — SCA is usually the fastest to adopt given how much risk sits in dependencies.
Can SCA findings be false positives?
Yes — a flagged CVE in a dependency doesn't always mean the vulnerable code path is actually reachable in your application.
Is DAST redundant if I already run SAST?
No — they catch fundamentally different categories of issue. Runtime and configuration problems generally aren't visible to static code analysis.
What's missing even if I use all three?
Business logic and access control testing, which typically require manual or expert-driven testing rather than automated pattern matching.