What are SAST and DAST?
SAST and DAST are two complementary methods of testing the security of software. SAST (static testing) analyzes the source code without running it, early in development, and points to the flaw at its origin. DAST (dynamic testing) attacks the running application from outside, as an intruder would, and finds what only shows up with the system running. Together they cover what neither sees alone: one finds the flaw in the code, the other finds the flaw in action.
How SAST and DAST work in the software cycle
The core idea is to test early and test always, the so-called shift-left: the closer to the writing of the code a flaw is found, the cheaper it is to fix. SAST and DAST act at different moments of development, which is exactly why they complement each other.
As the code is written (SAST)
Static testing reads the source code while it is being written, right in the developer's tool, and flags dangerous patterns, like a query vulnerable to injection, before the program even runs.
In the integration pipeline (automated SAST)
With each new version of the code, static testing runs automatically in the delivery pipeline (CI/CD). The flaw is blocked before it reaches production, without relying on anyone remembering to test.
With the application running (DAST)
Dynamic testing attacks the running system from outside, without seeing the code. It finds what only appears in operation: configuration errors, authentication flaws, unexpected behavior under attack.
Before production (fix)
SAST and DAST findings come together in a single, prioritized view, to be fixed before the software reaches the customer. Fixing here costs a fraction of what it would later.
Source: N-able (DevSecOps and the shift-left principle) and the application security consensus (OWASP).
SAST, DAST, and IAST: what each one sees
- SAST (static) Analyzes the source code without running it, with an inside view (white box). It runs early and fast, finds flaws at the source, like injection and unsafe use of data, but can produce false positives because it does not see the system in action.
- DAST (dynamic) Attacks the running application from outside, without seeing the code (black box). It finds runtime, configuration, and authentication flaws the code alone does not reveal, but only after the software is already running.
- IAST (interactive) An agent inside the application watches the code while it is used (grey box), combining both views. It runs during quality testing and reduces false positives, tying the flaw to the exact point in the code.
- SCA (dependencies) An important complement: composition analysis examines the third-party libraries and components the software uses, where many of today's flaws live. None of the three above covers this point on its own.
What is at stake for the business
All software carries flaws, and every year adds tens of thousands of new vulnerabilities (CVE Program / NVD), many hidden in the third-party libraries that almost every system uses. The point of SAST and DAST is to find those flaws before the attacker, and before the customer. The economics is the whole point: identifying a vulnerability during coding is dramatically cheaper than discovering it in production, when the fix involves urgency, rework, and the risk of an incident (the shift-left principle, the basis of DevSecOps). A flaw that slips into production can become a breach, and a breach costs, on average, $ 4.44 million worldwide (IBM, 2025). SAST and DAST do not compete: the static one finds the problem in the code, early; the dynamic one finds what only appears with the system running. Mature programs use both, and still cover the dependencies, because no method alone sees the whole picture.
How to put SAST and DAST into practice
Application testing does not have to be a bureaucratic gate at the end of the project. Well set up, it speeds delivery instead of blocking it:
- Integrate SAST early, in the pipelinePut static testing in the developer's tool and in the delivery pipeline, so the flaw shows up the moment it is written, when the cost to fix is minimal.
- Run DAST before productionTest the running application before it reaches the customer, to catch the configuration and authentication flaws the code does not reveal.
- Cover third-party dependenciesMany of today's flaws come from external libraries. A composition test (SCA) maps those components and warns when one of them has a known vulnerability.
- Handle findings by priority, not as a wallNo tool is perfect: there are false positives. Prioritize the real findings by risk instead of blocking everything, so the test helps the team instead of becoming friction.
- Combine application testing and penetration testingSAST and DAST cover the code and the behavior; the pentest proves the impact across the whole environment. Together they close the loop, from code to reality.
In practice
If your company develops or customizes software, ask the team one question: was the last serious vulnerability found in the code, during development, or only after the system was already live? The answer reveals whether security is entering early, when it is cheap, or late, when it costs dearly.
How Zamak supports application testing
For companies that develop, customize, or depend on their own software, Zamak Technologies helps embed security testing into the development cycle, with static and dynamic analyzers, many of them open source, and coverage of third-party dependencies. The work is done alongside your development team, reinforcing whoever already builds the product, so flaws show up early, while they are still cheap to fix. It is part of the managed cybersecurity in the Zamak Method, and a good starting point is the cybersecurity diagnosis.