SAST vs DAST: Key Differences Between Static and Dynamic Application Security Testing

SAST vs DAST: What’s the Difference?

Nowadays, hackers often target software applications to attack companies and steal data. To protect themselves, companies use special tools that examine their code for any security issues. This helps them fix problems early before hackers can exploit them.
The two main types of app testing are called SAST and DAST. SAST is short for “Static Application Security Testing.” DAST stands for “Dynamic Application Security Testing.”

While both SAST and DAST are important for app security, they actually check for problems in different ways. This article will explain what SAST and DAST do, what each one is good at, and when to use them.

Table comparing static application security testing (SAST) and dynamic application security testing (DAST) in three categories - what is tested, how it works, and optimal timing of use. SAST analyzes source code while DAST tests the running application.
This table highlights how static application security testing (SAST) and dynamic application security testing (DAST) take complementary approaches to identify vulnerabilities in software. SAST scans code early on while DAST confirms exploit prevention later against staged environments. Using both together provides comprehensive coverage.

By understanding the differences between these two key app tests, you’ll learn why using both SAST and DAST together provides the best security. They complement each other by constantly inspecting code for risks from different angles.

What is SAST?

SAST analyzes application code without executing it. SAST tools scan source code, binaries, and libraries to find security vulnerabilities. They use techniques like data flow analysis and control flow analysis to understand how data moves through code.

Benefits of SAST include:

  • Scans code early in development so vulnerabilities get fixed faster
  • Checks entire codebase for vulnerabilities
  • Good for detecting common flaws like SQL injection, cross-site scripting, etc.
  • Automated testing takes the burden off developers

Limitations of SAST:

  • Only analyzes code it has access to
  • Can generate false positives if certain test cases aren’t modeled properly
  • Struggles with highly complex code flows

When Should You Use SAST?

Use SAST early on as code gets written to find and fix security bugs quickly. Integrate SAST tools into CI/CD pipelines for automatic scans. SAST works well for modern code languages with available analyzers like Java, C#, and JavaScript.

What is DAST?

DAST tests applications from the outside by actually attacking the running app. DAST tools crawl sites to find all available content/functions, then launch exploits to analyze behavior and find potential vulnerabilities.

Benefits of DAST:

  • Tests the application in a running state which is how hackers would attack it
  • Good for validating often-missed flaws like authentication issues, access control weaknesses, etc
  • Helps prioritize patching known vulnerabilities being exploited in the wild

Limitations of DAST:

  • Typically conducted later in development so bugs persist longer
  • Won’t analyze areas of code it can’t reach by testing the UI/APIs
  • Can be disruptive to test directly on production sites

When Should You Use DAST?

Run DAST once functionality is built to confirm exploits can’t bypass implemented security controls. Use DAST assessment services or cloud-based DAST that spins up identical staging sites to safely test production environments.

Conclusion on SAST vs DAST

For optimal security, utilize both SAST early in development and DAST later on in production-like environments. This balances finding coding flaws quickly while also validating the assembled application handles real attacks securely. SAST and DAST together provide comprehensive application security visibility.

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