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What is Dynamic Application Security Testing (DAST)?


DAST Definition

Dynamic application security testing (DAST) is the process of using simulated attacks on a web application to identify vulnerabilities. By attacking an application the same way a malicious user would, this strategy assesses the program through an approach sometimes referred to as “outside in.” After executing the attacks, a DAST scanner studies the results to look for undesired outcomes. This data is then used to identify security flaws.

How Does Dynamic Application Security Testing (DAST) Work?

DAST comes in two different forms: manual DAST and automated DAST.

Manual DAST refers to the use of human expertise and specialized knowledge to identify vulnerabilities that DAST scanners can miss. On the other hand, automated DAST involves automatically feeding data into DAST tools to test your code.

DAST may deliver a long string of numbers, for instance, to help find a SQL injection vulnerability. In this way, DAST imitates the behavior of an SQL injection, and by seeing how the application code reacts to it, you can determine if it is susceptible to SQL code.

DAST systems emulate a range of attacks to find security flaws, test endpoints, and check the security of the data the application is supposed to keep private. Automated DAST security technologies can identify unexpected and problematic outcomes that can impact the user experience by simulating malicious attacks on the application—at various points in the development lifecycle.

Application Security Testing (AST) Categories

There are a few different AST categories, including SAST, DAST, IAST, and RASP.

Static Application Security Testing (SAST)

SAST searches the source code, binary, or byte code to identify vulnerabilities. It is a white-box testing tool that helps address underlying security problems by determining vulnerability sources. SAST solutions do not require your system to be running to conduct scans. Instead, unlike DAST, they examine an application from the "inside out."

Through quick feedback to developers regarding problems introduced during development, SAST lowers your programs’ security risks. By providing users with real-time access to suggestions, SAST helps developers discover security issues as they work. This makes vulnerability assessment faster. Because developers have these measures in place, they can write more secure code.

Dynamic Application Security Testing (DAST)

A DAST test, as described above, is an application security solution that can identify specific vulnerabilities in web applications while they are running. Because it is conducted without access to the internal source code or application architecture, a DAST test is often known as a "black-box test." In effect, it employs the same methods that an attacker would use to identify potential vulnerabilities.

This makes DAST an effective solution for identifying problems that can expose an application to cross-site scripting (XSS) or SQL injection. A DAST test can also identify issues in the setup process, as well as other problems with how the application functions.

Interactive Application Security Testing (IAST)

IAST examines the code during any activity that "interacts" with the application's functionality. In this way, IAST can detect issues that specifically arise when other applications or systems are interacting with an application. This enables the development team to predict issues that are likely to emerge when an application interfaces with other software.

Runtime Application Self-Protection (RASP)

RASP is a security solution created to give applications specialized security during runtime execution. RASP uses knowledge of an application’s internal data to spot dangers at runtime that other security solutions may miss. This is particularly important because many different systems have to work in sync during runtime, and RASP can detect even small issues that arise as a result of any of these interactions.

How To Choose Between SAST vs IAST vs DAST vs RASP

Choosing between DAST vs SAST, IAST, and RASP involves understanding the strengths of each methodology and how they fit your testing needs.


DAST's ability to use dynamic code analysis to spot runtime problems—weaknesses that cannot be seen when a program is not running—is one of its main advantages. DAST also examines how an application actually responds to an attack, providing valuable information about the likelihood of a vulnerability being exploited.


SAST is excellent at finding vulnerabilities as code is being produced. Without SAST, a development team will likely not catch problems until later in the software development lifecycle (SDLC). Also, SAST can pinpoint coding errors, making it simple for developers to identify and address vulnerabilities.


IAST supports continuous testing, monitoring, evaluation, and validation in real time, which is particularly helpful for DevSecOps teams. IAST provides critical threat alerts. To reduce false positives that may waste the development team's time, it actively verifies whether a vulnerability is exploitable by an attacker. IAST solutions also enable developers to address security flaws in their code by spotting risky lines of code and helping to remediate them.


RASP operates on a server while an application is running. It examines an application's behavior to spot attacks and quickly address them. To do this, the RASP utility assumes control of an application when a security incident happens and tries to resolve the problem.

So choosing between SAST, DAST, IAST, and RASP may depend on where you are in the development lifecycle and the kinds of vulnerabilities you may be most concerned about. In many cases, It is best to use a combination of each as you develop and test an application. For instance, as you build out code, you may use SAST. But once the first iteration is complete, you can use RASP to check for issues.

Key differences between DAST and SAST

Why is DAST the Future of Application Security (AppSec)?

DAST represents the future of AppSec for various reasons that include the following:

  1. Language-agnostic: DAST is the only security testing technique that is not dependent on a particular programming language. DAST only checks the inputs and outputs of your system; it does not examine the source code, bytecode, or assembly code.
  2. Makes it easy to retest vulnerabilities that have been patched: If a security flaw is discovered and successfully reproduced, it can be added to the DAST test suite. This is valuable because the functions that caused the issue may end up in every subsequent version of the application. But because the problematic issues are stored in the DAST system, DAST can identify them so they do not end up in the version your development team releases.

Pros of DAST

Here is a basic breakdown of the advantages of DAST.

  1. It works with different kinds of applications.
  2. It immediately identifies vulnerabilities that attackers can take advantage of.
  3. It does not need access to an application’s source code to work.

Cons of DAST

As is the case with most technologies, there are some downsides to DAST, too:

  1. It cannot find exactly where in an application’s code the vulnerability is.
  2. You need to have security knowledge to understand what is in a DAST report.
  3. The testing process can take a long time.

How to Integrate DAST into the Software Development Lifecycle (SDLC)?

If you want to integrate DAST into your software development lifecycle, here are three ways to do it:

1. Adopt a Comprehensive Approach to Web Application Security Testing

It is best to use DAST alongside other testing tools, not in isolation. While DAST provides security teams with timely insight into how web applications perform in production, businesses frequently use DAST in conjunction with other security testing methods like SAST and application penetration testing.

2. Use DAST Consistently and Early for Best Results

Early and frequent testing throughout the software development lifecycle will, in the long run, save you time. It is easier to use DAST to pinpoint a problem early on than wait until the application is nearly finished. In this way, you eliminate problems that can introduce vulnerabilities into other facets of the application.

3. Integrate DAST into DevOps

When used in conjunction with DevOps, DAST pinpoints critical issues, enabling DevOps to resolve them. Because the DevOps process emphasizes quick iterations, using DAST throughout the development process can help your DevOps team make each version safe.

How Fortinet Can Help

FortiDAST performs automated black-box dynamic application security testing of web applications to identify vulnerabilities that bad actors may exploit. FortiDAST combines advanced crawling technology with FortiGuard Labs’ extensive threat research and knowledge base to test target applications against OWASP Top 10 and other vulnerabilities. Designed for Development, DevOps and Security teams, FortiDAST generates full details on vulnerabilities found - prioritized by threat scores computed from CVSS values – and provides guidance for their effective remediation.


What is dynamic analysis security testing?

Dynamic application security testing (DAST) uses simulated attacks on a web application to identify vulnerabilities.

What is the differences between SAST and DAST?

Static application security testing (SAST) searches the source code, binary, or byte code to identify vulnerabilities, and DAST involves attacking code to see if it breaks. By using both, a security team is testing an application from both the inside (with SAST) and the outside (with DAST).

What are the benefits of DAST?

  1. It works with different kinds of applications.
  2. It immediately identifies vulnerabilities that attackers can take advantage of.
  3.  It does not need access to an application’s source code to work.