SAST, DAST, SCA and MAST: Differences and How to Choose

SAST analyzes source code without running it, DAST attacks a running application from the outside, SCA finds vulnerabilities in open-source dependencies, and MAST tests mobile applications. These are not competitors but layers of the same defense: start with SCA and SAST, then add DAST, and bring in MAST and binary analysis as needed.

SAST: static application security testing

Static Application Security Testing analyzes source (or binary) code without running the application. The OWASP DevSecOps Guideline describes SAST as a form of static code analysis and part of white-box code review. The scanner builds a model of the program, tracks data flows from input points to dangerous functions, and finds SQL injection, XSS, path traversal, insecure cryptography, and hardcoded passwords and keys.

• Pros: works at the earliest stages, in the IDE or on a pull request; points to the exact line of code, so developers can fix the defect faster.
• Cons: does not see problems in the environment configuration; without tuning, rules can produce false positives; quality depends heavily on support for a specific language and framework.

We cover how to evaluate SAST analyzers before buying in our article how to choose a SAST analyzer.

DAST: dynamic testing

Dynamic Application Security Testing is a black-box approach: the tool attacks a running application from the outside, the way an attacker would, sending requests, injecting malicious input and analyzing responses. According to OWASP, DAST is especially useful for checking input and output handling, authentication, and server configuration errors, and it requires neither source code nor knowledge of the framework.

• Pros: finds vulnerabilities that are actually exploitable, as well as configuration, authentication and session problems; does not depend on the development language; once configured, needs minimal involvement, for example nightly scheduled runs.
• Cons: requires a deployed test environment; runs later than SAST; does not point to the line of code that caused the vulnerability.

For regular automated scanning of dozens or hundreds of websites, teams use platforms such as Burp Suite DAST; for manual testing by penetration testers, Burp Suite Professional.

SCA: software composition analysis

Software Composition Analysis checks third-party open-source libraries, which make up a significant part of the code in modern applications. SCA finds components with known vulnerabilities (CVEs), malicious packages and problematic licenses, and produces an SBOM, the list of all components. The use of vulnerable and outdated components has its own category, A06, in the OWASP Top 10 2021.

Log4Shell showed the scale of the risk: vulnerability CVE-2021-44228 in the Apache Log4j library allowed an unauthenticated attacker to execute code remotely through a specially crafted request. In December 2021, CISA described active, mass exploitation. Because Log4j is embedded in products from many different vendors, many organizations were affected. SCA solutions such as Sonatype Lifecycle and Repository Firewall let you quickly find where a vulnerable component is used and block a malicious package before it reaches the build. For more on component inventories, see our article on SBOMs.

MAST: mobile application security

Mobile Application Security Testing combines static and dynamic analysis for Android and iOS. The reference points are OWASP projects: the MASVS verification standard, with requirement groups for data storage, cryptography, authentication, network communication, platform interaction, code quality, reverse-engineering resilience and privacy, and the MASTG testing guide. Typical findings include insecure data storage on the device, weak traffic protection, data leaking through logs, and excessive permissions.

Binary analysis

Binary analysis lets you check applications for which no source code is available: legacy systems, contractor solutions and third-party builds. It is especially relevant during software acceptance and when searching for undeclared functionality, when you cannot take the vendor's word for it.

Comparing tool classes

• SAST — what it checks: your own code; when: while writing code and on pull requests; needs code: yes.
• SCA — what it checks: open-source dependencies; when: during builds and continuously; needs code: manifests or the build.
• DAST — what it checks: the running web application and API; when: on a test environment and in production; needs code: no.
• MAST — what it checks: mobile applications; when: before publication; needs code: preferably.
• Binary — what it checks: executable files; when: during software acceptance; needs code: no.

IAST (interactive application security testing, using an agent inside the application) is less common and is usually considered a complement to the classes above, not a replacement.

What to choose first?

The answer "just one thing" is almost always wrong, because the tools complement each other. A practical order for most companies:

1. SCA — quick results, few false positives, and it covers the most widespread risk.
2. SAST — built into pull requests, and it helps developers learn to write secure code.
3. DAST — regular scanning of the external perimeter of web applications.
4. MAST and binary analysis — if you have mobile applications or software from contractors.

Full-cycle platforms such as DerScanner combine SAST, DAST, SCA, MAST and binary analysis in one interface, which simplifies rollout and reporting. To avoid buying blind, run a comparative test on your own repositories. How to organize this within a month is described in our article on a 30-day SAST and SCA pilot.

How to build checks into the process

Each check has its place in the pipeline. SAST and secrets scanning run on pull requests, SCA runs at build time, and DAST runs on a test environment and regularly in production. Agree in advance which findings block a release and which become tasks. Start with reporting and tighten the rules gradually, otherwise the team will drown in thousands of findings and begin bypassing the checks.

Criteria for choosing a specific product

Once the tool class is defined, the product choice begins. There is no universal "best" scanner: the result depends on your stack and processes. Things to look at when comparing:

• Language and framework support. The list of languages in a vendor presentation says nothing about analysis depth. Test on your own code: does the scanner find known defects in your projects, and how well does it handle your frameworks?
• False positive rate. If developers spend time sorting through noise, they will stop trusting the tool. Measure the share of confirmed findings, not the number of findings.
• Integrations. The scanner should work in your CI/CD, task tracker and IDE. A finding that cannot be handed to a developer in their usual tool will stay in a report.
• Deployment model. For banks and the public sector, it is often important that source code does not leave the organization's perimeter. That is why many companies in the region consider solutions installed on their own infrastructure (on-premise).
• Reporting. Security leadership needs summaries by application, trends and remediation deadlines, not just a list of defects.

Common mistakes when choosing

• One tool for everything. Expecting SAST to cover both dependencies and environment configuration creates blind spots.
• Enabling all rules at once. Thousands of findings in old code paralyze the team. Start with critical vulnerability classes and new changes in pull requests, and work through the accumulated debt gradually.
• Buying without testing on your own data. Compare candidates on the same repositories, otherwise you are comparing presentations, not products.
• Ignoring the process. A tool without assigned owners for remediation and agreed quality gates becomes a report generator.
• Forgetting mobile and third-party code. Mobile clients and contractor software often stay outside the checks, even though incidents often come through them.

Who does what on the team

Different tool classes serve different roles. Developers work with SAST and SCA: results appear in the pull request and the IDE. The DevOps engineer is responsible for running the checks and enforcing policies in the pipeline. The penetration tester uses DAST and manual tools such as Burp Suite for deep testing of critical applications. The security lead reviews summary reports and metrics across all classes. If these roles are not defined in advance, checks either do not run or their results never reach the people who can fix them.

Frequently asked questions

Sources

• OWASP DevSecOps Guideline: Static Application Security Testing
• OWASP DevSecOps Guideline: Dynamic Application Security Testing
• OWASP Mobile Application Security (MASVS and MASTG)
• CISA: Apache Log4j Vulnerability Guidance