安全测试（SAST、DAST、IAST）

Protecting your backend applications is absolutely vital. Security testing helps you find and fix vulnerabilities before attackers can exploit them.

It's a proactive approach, crucial for maintaining trust and preventing costly data breaches. It's a key part of building secure software from the ground up.

SAST (Static Application Security Testing) analyzes your application's source code, bytecode, or binary code without actually running it.

Think of it as a super-powered linter for security flaws. It's often called "white-box" testing because it needs access to your internal code. SAST helps you "shift left" by finding issues early in development.

SAST is great for early detection, but it has its quirks:

• Pros: Finds vulnerabilities very early in the SDLC, helps enforce coding standards, can cover 100% of the code.
• Cons: Can produce many false positives, doesn't detect runtime issues or configuration flaws, requires source code.

Common SAST findings include patterns for SQL injection, cross-site scripting (XSS) in code, and hardcoded secrets.

DAST (Dynamic Application Security Testing) tests your application while it's running. It simulates attacks from the outside, just like a malicious user would.

This is often called "black-box" testing because it doesn't need access to the source code. DAST checks how the application behaves in a real environment, focusing on runtime behavior and configuration.

DAST gives you an attacker's view, but also has specific characteristics:

• Pros: Finds runtime vulnerabilities, configuration errors, and environment-specific issues. No source code needed.
• Cons: Can't test unexecuted code paths, might produce false negatives, typically performed later in the SDLC.

DAST can uncover issues like broken authentication, session management flaws, and server misconfigurations.

IAST (Interactive Application Security Testing) combines elements of both SAST and DAST. It works by deploying an agent or instrumentation inside the running application.

This agent observes the application's behavior and data flow in real-time as it's being used or tested. It's like having an internal security expert watching everything.

IAST offers a powerful blend of insights:

• Pros: High accuracy with fewer false positives than SAST/DAST alone, identifies the exact line of code for vulnerabilities, works during regular functional testing.
• Cons: Requires an agent to be installed, might have some performance overhead, only tests executed code paths.

IAST provides detailed insights into how vulnerabilities manifest during runtime, pinpointing their source.

When should you use each testing type?

• Early Development: SAST for quick feedback on code quality and common patterns.
• QA/Staging: DAST to test the deployed application from an attacker's perspective.
• Continuous Testing: IAST for integrated, accurate findings during automated or manual functional tests.

Often, a combination of these tools provides the most comprehensive security coverage.

Integrating SAST, DAST, and IAST into your Continuous Integration/Continuous Delivery (CI/CD) pipeline is key to DevSecOps:

• SAST: Run on every code commit or pull request.
• DAST: Triggered after deployment to a test environment.
• IAST: Runs continuously during functional tests in dev/staging.

This automation ensures security is a continuous process, embedded throughout the development lifecycle, not an afterthought.

Which of the following statements correctly describe the characteristics of SAST, DAST, or IAST?

We've explored the three main types of application security testing:

• SAST: Static analysis, early detection, no execution.
• DAST: Dynamic analysis, running app, black-box view.
• IAST: Interactive analysis, hybrid approach, high accuracy.

Combining these methods within your DevSecOps pipeline provides comprehensive security coverage. In the next lesson, we'll dive into incident response planning!