SAST, DAST, and SCA: Essential Layers of Application Security (Shift Left)
SAST vs DAST vs SCA: How SAST, DAST, SCA Transform Application Security (Shift-Left Explained)
SAST, DAST, and SCA are more known as shift left tools.
What is Shift Left?
Shift Left is all about bringing security into the development process right from the earliest stages of software development.
SAST, DAST, and SCA form a robust, multi-layered approach to identifying and mitigating vulnerabilities at the early stages of the development cycle.
- SAST (Static Application Security Testing)
- DAST (Dynamic Application Security Testing)
- SCA (Software Composition Analysis)
Let’s explore each of these tools and how they work together to help to develop a secure application.
SAST: Finding Vulnerabilities Early
SAST tools analyze source code line by line, even before it’s compiled or executed, searching for potential vulnerabilities like:
- SQL injection flaws
- Cross-site scripting (XSS) issues
- Open Redirect
- Server-Side Request Forgery
- Other common coding errors
Some SAST tools: Checkmarx, SNYK etc.
How it Works: SAST tools analyze code patterns, data flow, and potential injection points against a database of known vulnerabilities and coding standards (like OWASP Top 10 or CWE).
Pros:
- Early detection in the development lifecycle
- Can find deep-rooted vulnerabilities
- Integrates well into developer workflows/IDE
Cons:
- Can generate false positives (identifying issues that aren’t real threats)
- Might miss vulnerabilities that only surface when the application is running. (it may be detected by DAST)
DAST: Attacking From the Outside In
DAST analyzes a running application, it tests the application from the outside in, like a real hacker attack. It probes running web application, sending many malicious inputs to try and expose vulnerabilities that are difficult to catch with static analysis:
- Input validation weaknesses
- Authentication and authorization problems
- Session management flaws
Some DAST tools are: Acunetix, Checkmarx DAST, OWASP ZAP etc.
How it works: DAST tools work as “black boxes” — they don’t need access to source code. It sends attack payloads or fuzzing inputs to the application’s interfaces and finds out vulnerabilities.
Pros:
- Identifies vulnerabilities that might be missed by SAST
- Good for testing runtime environment security
- No false positives — reported issues are real risks
Cons:
- Finds vulnerabilities later in the development lifecycle
- May have difficulty testing the full range of application functionality
SCA (Software Composition Analysis)
SCA is all about understanding the ingredients i
n a software recipe. It scans the application to identify all the open-source libraries, frameworks, and third-party components used. These are then checked against databases of known vulnerabilities(CVE and OWASP).
Some SCA tools are: Veracode Software Composition Analysis, SNYK,
How it Works: SCA tools build a software inventory, matching components against known vulnerability databases (like CVE, OWASP).
Pros:
- Critical for managing risk in modern development, which heavily relies on third-party code
- Proactive identification of vulnerabilities in external components
Cons:
- Requires diligent maintenance of software inventory
- Might report vulnerabilities not relevant to how you’re using a component
SAST, DAST, and SCA don’t compete; they provide multiple layers of security to develop a secure application:
- SAST: Catches coding errors at the source, the earliest possible fix.
- DAST: Finds runtime problems stemming from how components interact.
- SCA: Ensures software isn’t built on a foundation of vulnerable external code.
Why Do They Matter?
These three tools complement each other in a strategy of “Shift Left.” This means integrating security testing early in the software development life cycle (SDLC), and catching problems before they make it into production environment. It saves money, time, and the headache of dealing with breaches when they are detected at production.
These tools can be integrated into CI/CD (Continuous Integration/Continuous Delivery) workflow to run scans automatically with each code change and deployment.
Let me know if you’d like a deeper dive into a specific tool — SAST, DAST, or SCA — or perhaps some examples of common vulnerabilities they help detect.
Follow me on LinkedIn: https://www.linkedin.com/in/ajay-monga2/