SAST vs DAST: Understanding Security Testing Approaches

Security testing is a vital component of the software development lifecycle (SDLC), both for organizations that develop software to sell and those that develop for in-house use. Two of the most common security testing methods are static application security testing (SAST) and dynamic application security testing (DAST). But in the head-to-head world of SAST vs DAST, what should teams know?

How early and how often can teams deploy them without crushing developer velocity? And can either offer meaningful exploitability context without drowning teams in noise? How do they fare with modern container architectures, coordinating supply chain dependencies, and APIs?

We’re breaking down these approaches to application security testing, examining their key differences and best practices. 

What is SAST? What is DAST?

SAST is white-box, source code analysis. SAST is a great way to test early in the SDLC, but it can overwhelm teams with noise and false positives, especially on large monolithic repositories or legacy codebases.

DAST is black-box, runtime testing. It comes with more actionable, runtime-specific vulnerabilities, but often too late in CI/CD for fast-moving teams. Further, it can’t cover logic flaws well or reach the parts of an application beyond authorization.

Is SAST or DAST Best?

Codebases have flaws, but not every flaw is a vulnerability, and not every vulnerability matters. The purpose of security testing isn’t to chase perfection for its own sake, but to surface risks that matter most. In the real world, developers choose SAST vs. DAST tools almost equally in order to make that happen. 

According to Gitlab’s 2022 Global DevSecOps Survey, 53% of developers run SAST scans, while a nearly identical number, 55%, use DAST testing.

The simplest answer is that neither SAST nor DAST is better. Teams use SAST to catch issues early, using it often and filtering carefully. It’s best for identifying dangerous code patterns before they ever run. But teams also use DAST to catch runtime issues SAST doesn’t — or can’t, since they emerge at runtime.

Specific kinds of flaws are closely correlated with testing types:

SAST is best for insecure coding patterns, secrets in code, and insecure dependencies.

DAST is best for broken authentication, exploitable input/output, and logic flaws.

Let’s go over the basics of how each solution works.

Advantages and Limitations of SAST

SAST is a testing method where static code is scanned for vulnerabilities or logical fallacies that could interfere with the normal operation of an application. 

The name “static testing” refers to scanning the source code of the application as it is written. It’s a shift-left approach, and in this process, DevSecOps teams examine code for any misconfigurations, missing dependencies, compliance violations, or other potential issues. 

There are a few advantages to this method of examining static code:

• Early detection of vulnerabilities: Because the source code is scanned before deployment, SAST can catch potential vulnerabilities, flag them to developers, and check if they are properly resolved before they are pushed to the live application. Code is simpler and less expensive to fix at this early stage.
• More secure code overall: Running SAST early and often can help reduce the number of rewrites needed to the application source code later on in the development lifecycle. 
• Improved compliance and coding consistency: The integration of SAST into CI/CD pipelines lets organizations enforce security policies at scale. Automated scans help detect deviations from best practices and ensure adherence to regulatory requirements. Especially in complex development environments where multiple teams contribute to code, SAST can help maintain a consistent security posture.  

Despite their usefulness, SAST solutions have their limitations. SAST solutions can only analyze static source code — but in the real world, some vulnerabilities emerge at runtime. Issues like authentication flaws, privilege escalation, race conditions, and injection attacks dependent on execution context typically are not flagged by SAST tools.  

SAST tools may also be prone to false positives. SAST tools are typically built to analyze code without the full context of the application’s threat model. Without proper tuning, security teams may need to expend substantial effort to triage false positives and identify actual vulnerabilities. 

Finally, SAST tools are only as good as their database of vulnerabilities. Without continuous maintenance, SAST solutions may fail to detect emerging threats, increasing the risk of overlooked security flaws in application source code.

Advantages and Limitations of DAST

DAST is a method of application testing that focuses solely on the runtime environment. A DAST test examines applications once they are launched and running.

DAST solutions have no visibility into the underlying application source code. Instead, they function by simulating how an attacker might try to compromise the runtime environment, delivering valuable insights into runtime vulnerabilities.

DAST tools check running applications against databases of known software vulnerabilities, flagging any active runtime issues they detect. DAST is especially useful for detecting misconfigurations in servers or databases, as well as authentication and encryption issues that could allow unauthorized access. DAST can also test APIs or web services connected to the application, introducing a valuable layer of cybersecurity to the broader IT environment where the application operates.

Because DAST scans require a complete working application, they are used in later stages of the application development process. These tools are often deployed at or near the end of the SDLC, after all code reviews have been completed and the static code has been secured against vulnerabilities. DAST is particularly effective when the application is running in its real-world environment, but that limits how much it can do to avoid the lengthy and costly re-architecting of apps.

But How Do SAST and DAST Really Compare?

What are the key differences between SAST and DAST? And when should a DevOps team deploy one over the other? If you’re not familiar with the basics, start here:

	Static Application Security Testing (SAST)	Dynamic Application Security Testing (DAST)
What is scanned?	Source code in the development environment	The running application in a staging or live environment
What does it look for?	Code-level vulnerabilities, misconfigurations, and license violations	Runtime issues in the environment, architecture, or integrations
What can’t it look for?	Runtime-specific vulnerabilities	Issues in the application’s source code
When is it used in the SDLC?	Early in development, integrated into the build pipeline	Later in the SDLC, during QA or post-deployment
What does it excel at finding?	Finding known code flaws and open-source risks	Identifying real-world, environment-specific security issues
Is it programming language-specific?	Yes, depends on the language support of the tool	No, language-agnostic since it tests behavior, not code

Both are types of testing that help Appsec teams make their apps more secure. There’s also Runtime Application Self-Protection (RASP) that lives inside the running application to actively monitor it in real time. Unlike SAST and DAST, which are external scanners, RASP runs alongside apps in production. They can inspect runtime behavior, detect attacks like SQL injection, XSS, or command injection — and block malicious inputs immediately. 

RASP isn’t always the right fit. For one, it adds performance overhead. It fails to scale well, especially in cloud-native environments. RASP was built for monolithic apps and long-lived VMs, so SAST and DAST fill a gap for apps that will run in cloud environments.

Integrating SAST and DAST for Complementary Coverage

It’s unlikely that the companies that choose to use SAST testing are an entirely different group than those that choose DAST: the reality is that each solves different problems at different phases of the SDLC — it’s likely that teams using SAST are also the ones using DAST. 

It’s not SAST vs DAST. It’s about how and when to use both. Most mature teams leverage both because they catch different classes of vulnerabilities at different stages of the SDLC for a layered, complementary defense when integrated well.

Here are some best practices: 

• Integrate testing where it adds value, not friction and slowed processes. Embed SAST into the CI pipeline at the pull request level with scoped scanning, not full repository scanning every time. Run DAST on staging environments post-deployment, especially against real user workflows and authenticated endpoints.
• Automate without increasing the burden on humans. Automate scans but filter results based on severity, exploitability, and code ownership. Correlate SAST/DAST with asset and exposure risk, especially if using a CNAPP.
• Prevent security regressions in real time. Block merges on critical SAST findings that override workflows. DAST gating rules can be used for final QA, especially for apps exposed to the public. It’s all meant to help teams master enforcement without relying on manual reviews.
• Keep signals relevant. Update rule sets and analyzers to reflect the latest CVEs. Tune SAST to focus on real issues to reduce noise.
• Make results actionable. Integrate scans into tools that are already in the workflow, making sure that teams from DevOps to product have shared visibility into critical issues, and use dashboards that track key metrics, like time to resolve.

Considering Tools Beyond SAST and DAST

No single tool can offer full visibility into modern application risks. Even with coverage across the lifecycle, teams typically rely on multiple tools for full coverage. But as the security stack grows, so does the pressure to consolidate. Let’s go deeper into cutting noise and reducing tool sprawl by understanding other closely related solutions and how each solves a distinctive problem.

	SAST	DAST	IaC Scanning	SCA	Secrets Detection	CNAPP
What it scans	Source code	Running application	Infrastructure-as-code configs	Open-source packages and dependencies	Hardcoded credentials and tokens	Misconfigurations, lateral movement, and exposures
When it’s used	During development	Post-deployment (QA/production)	Pre-deploy (in CI or PR)	In dev and CI pipelines	At commit, at CI/CD, or image build	Post-deploy runtime
What it finds	Code flaws, logic issues	Runtime behavior and logic flaws	Misconfigurations before deploy	Known CVEs, license risks	Secrets in code or environments	Correlating risk across the stack and lifecycle
Understands runtime context?	No	Partially	No	No	No	Yes
Programming Language Dependent?	Yes	No	No	Yes	No	No
Prioritizes by exploitability?	No	Limited	No	No	No	Yes
Best at	Secure code early	Behavioral bugs, exposed endpoints	Catching risky configurations before deployment	Managing open-source risk	Prevents credential exposure	Correlating risk across stack and lifecycle
What it misses	Runtime issues, misconfigurations	App code flaws	Runtime drift, actual cloud state	Runtime behavior, code logic	Runtime secrets, cloud access risks	App logic, unless integrated externally

For shift-left teams, SAST, SCA, and secrets detection can be combined: SAST catches logic bugs and insecure patterns without redundancy, SCA tracks vulnerable packages and licenses, and secrets detection helps to avoid committing credentials, all before the deployment stage.

Use this combination if dev teams push code to production daily and need guardrails early on. Consolidate when these capabilities are already covered by a DevSecOps platform or a CNAPP.

DAST and CNAPP is another typical pairing, since DAST simulates runtime behavior but has blind spots in modern architectures. CNAPP can monitor runtime behavior and expose reachable attack paths based on traffic, identity, and cloud misconfigurations. Lean on CNAPP for runtime-aware exposure insights without manual scripting or test payloads. 

Upwind Complements Security Testing Across the Lifecycle

Upwind’s runtime-focused CNAPP cuts the noise for insight into code that’s exposed and poses a real-life threat. But with integration in the CI/CD lifecycle, teams don’t have to choose to shift left vs. right. Instead, they’ll get seamless, efficient detection that’s prioritized for critical threats and incorporated into new code at the build stage.

Upwind provides a comprehensive scan of all resources, automatically identifying and cataloging everything it finds for full 360-degree visibility of the entire environment. With Upwind, DevSecOps teams can perform a deep assessment of Layers 3, 4, 7, and DNS alongside process-level identity and scanning of all API connections. Want to see how? Reach out today.

Frequently Asked Questions 

Can SAST and DAST replace each other? 

No. SAST and DAST are not replacements for each other. 

Static Application Security Testing (SAST) is a critical method of ensuring that code as written does not include any obvious errors prior to deployment. This static analysis isn’t a testing tool for the dynamic cloud environment, but for code alone.

DAST makes sure that all applications operate the way they should when they reach the runtime environment. The two application security methodologies examine different components of the application and are most often used in tandem to ensure applications are secure and function as expected. 

How do you integrate both approaches effectively? 

To integrate SAST and DAST effectively, run SAST early in the CI pipeline to catch insecure code before deployment. Run DAST in staging to detect runtime issues like auth flaws and exposed endpoints. 

Here’s the key to integration: prioritize findings where SAST and DAST overlap and correlate results with runtime context for better triage. Automate both scans, enforce gating on critical issues, and route alerts to the right teams via existing dev tools for faster remediation.

What are the cost implications of each approach? 

The primary cost implications of static application security testing (SAST) lie in the initial tool purchase, potential false positive analysis time for developers, and the need to integrate it effectively into the development workflow. These costs are outweighed by delivering more secure code and catching vulnerabilities earlier in the process. 

The cost implications of Dynamic Application Security Testing (DAST) primarily involve the initial purchase or subscription cost of the DAST tool and the time required for scanning and remediation of identified vulnerabilities. Although the time commitment can increase if issues are discovered late in the development cycle, the potential cost savings from preventing data breaches by identifying vulnerabilities early on makes DAST a cost-effective solution.