Software Integrity


SAST vs. DAST: What’s the best method for application security testing?

High profile security breaches are leading to heightened organizational security concerns. Firms around the world are now observing the consequences of security breaches that are becoming more widespread and more advanced. Due to this, firms are ready to identify vulnerabilities in their applications and mitigate the risks.

Two ways to go about this are static application security testing (SAST) and dynamic application security testing (DAST). These application security testing methodologies are used to find the security vulnerabilities that make your organization’s applications susceptible to attack.

Which one is right for your organization?

The two methodologies approach applications very differently. They are most effective at different phases of the software development life cycle (SDLC) and find different types of vulnerabilities. For example, SAST detects critical vulnerabilities such as cross-site scripting (XSS), SQL injection, and buffer overflow earlier in the SDLC. DAST, on the other hand, uses an outside-in penetration testing approach to identify security vulnerabilities while web applications are running.

Key differences between SAST and DAST

Static Application Security Testing (SAST)
Dynamic Application Security Testing (DAST)
White box security testing
  • Tester has access to the underlying framework, design and implementation.
  • Tests the application from the inside-out.
  • The developer approach.
Black box security testing
  • Tester has no knowledge of the technologies or frameworks that the application is built on.
  • Tests the application from the outside-in.
  • The hacker approach.
Requires source code
  • Doesn’t require a deployed application.
  • Analyzes source code or binaries without executing the application.
Requires a running application
  • Doesn’t require source code or binaries.
  • Analyzes software by executing it.
Finds vulnerabilities earlier in the SDLC
  • The scan can be executed as soon as code is deemed feature-complete.
Finds vulnerabilities towards the end of the SDLC
  • Vulnerabilities can be discovered after the development cycle is complete.
Less expensive to fix vulnerabilities
  • Since vulnerabilities are found ealier in the SDLC, it’s easier and faster to get a vulnerability remediated.
  • Findings can often be fixed before the code enters the QA cycle.
More expensive to fix vulnerabilities
  • Since vulnerabilities are found towards the end of the SDLC, remediation often gets pushed into the next cycle.
  • Critical vulnerabilities may be fixed as an emergency release.
Runtime and environment-related issues can’t be discovered
  • Sinces the tools cans static code, runtime vulnerabilities can’t be discovered.
Runtime and environment-related issues can be discovered
  • Since the tool uses dynamic analysis on an application, it is able to find runtime vulnerabilities.
Typically supports all kinds of software
  • Examples include web applications, web services and thick clients.
Typically scans only apps like web applications and web services
  • DAST is not useful for other types of software.