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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.

SAST vs. DAST

SAST vs. DAST

Static application security testing (SAST) and dynamic application security testing (DAST) are both methods of testing for security vulnerabilities, but they’re used very differently. Here are some key differences between the two:

SAST

DAST

White box security testing

The tester has access to the underlying framework, design, and implementation. The application is tested from the inside out. This type of testing represents the developer approach.

Black box security testing

The tester has no knowledge of the technologies or frameworks that the application is built on. The application is tested from the outside in. This type of testing represents the hacker approach.

Requires source code

SAST doesn’t require a deployed application. It analyzes the sources code or binary without executing the application.

Requires a running application

DAST doesn’t require source code or binaries. It analyzes by executing the application.

Finds vulnerabilities earlier in the SDLC

The scan can be executed as soon as code is deemed feature-complete.

Finds vulnerabilities toward the end of the SDLC

Vulnerabilities can be discovered after the development cycle is complete.

Less expensive to fix vulnerabilities

Since vulnerabilities are found earlier in the SDLC, it’s easier and faster to remediate them. Findings can often be fixed before the code enters the QA cycle.

More expensive to fix vulnerabilities

Since vulnerabilities are found toward the end of the SDLC, remediation often gets pushed into the next cycle. Critical vulnerabilities may be fixed as an emergency release.

Can’t discover run-time and environment-related issues

Since the tool scans static code, it can’t discover run-time vulnerabilities.

Can discover run-time and environment-related issues

Since the tool uses dynamic analysis on an application, it is able to find run-time 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.

SAST and DAST techniques complement each other. Both need to be carried out for comprehensive testing.

Read The AppSec alphabet soup: A guide to SAST, DAST, IAST, and RASP

 

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