Differences Between SAST, DAST, IAST, And RASP

This tutorial explains the differences between the four major security tools. We will compare them SAST vs DAST and IAST vs RASP:

It is no longer a usual business in terms of software security within the software development life cycle, as different tools are now readily available to ease the work of a security tester and help a developer to detect any vulnerabilities at an early stage of development.

Here we will analyze and compare four such major security tools SAST, DAST, IAST, And RASP.

Differences between SAST, DAST, IAST, and RASP

Differences Between SAST, DAST, IAST, And RASP

For some good years now, software applications have positively affected the way we work or do business. Most web applications now store and handle increasingly more sensitive data that has now brought the issue of data security and privacy security.

Fact Check: According to research conducted by Verizon in 2020 on Data Breach it was reported that 43% of breaches were attacks on web applications, while some other security breaches were as a result of some sort of vulnerabilities in web applications.

verizon research stats on Data Breach

In this tutorial, we will analyze the four major security tools that organizations should have at their disposal which can help developers and testers to identify vulnerabilities in their source code at different stages of the Software Development Lifecycle.

These security tools include SAST, DAST, IAST, and RASP.

History of Application Security Automation

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What Is SAST

The acronym “SAST” stands for Static Application Security Testing.

Many people tend to develop an application that could automate or execute processes very fast and also improve performance and user experience thereby forgetting the negative impact an application that lacks security could cause.

Security testing is not about speed or performance rather it is about finding vulnerabilities.

Why is it Static? This is because the test is done before an application is live and running. SAST can help to detect vulnerabilities in your application before the world finds them.

How Does It Work

SAST uses a testing methodology of analyzing a source code to detect any traces of vulnerabilities that could provide a backdoor for an attacker. SAST usually analyzes and scans an application before the code is compiled.

The process of SAST is also known as White Box Testing. Once a vulnerability is detected the next line of action is to check the code and patch the code before the code will be compiled and deployed to live.

White Box Testing is an approach or method that testers use to test the inner structure of software and see how it integrates with the external systems.

What Is DAST

“DAST” stands for Dynamic Application Security Testing. This is a security tool that is used to scan any web application to find security vulnerabilities.

This tool is used to detect vulnerabilities inside a web application that has been deployed to production. DAST tools will always send alerts to the security team assigned for immediate remediation.

DAST is a tool that can be integrated very early into the software development lifecycle and its focus is to help organizations to reduce and protect against the risk that application vulnerabilities could cause.

This tool is very different from SAST because DAST uses the Black Box Testing Methodology, it conducts its vulnerability assessment from outside as it does not have access to the application source code.

DAST is used during the testing and QA phase of SDLC.

What Is IAST

IAST” stands for Interactive Application Security Testing.

IAST is an application security tool that was designed for both web and mobile applications to detect and report issues even while the application is running. Before someone can comprehend the understanding of IAST fully, the person must know what SAST and DAST actually mean.

IAST was developed to stop all the limitations that exist in both SAST and DAST. It uses the Grey Box Testing Methodology.

How Exactly Does IAST Work

IAST testing occurs in real-time just like DAST while the application is running in the staging environment. IAST can identify the line of code causing security issues and quickly inform the developer for immediate remediation.

IAST also checks the source code just like SAST but this is at the post-build stage unlike the SAST that occur while the code is been built.

IAST agents is usually deployed on the application servers, and when DAST scanner performs it’s work by reporting a vulnerability the IAST agent that is deployed will now return a line number of the issue from the source code.

The IAST agents can be deployed on an application server and during functional testing performed by a QA tester, the agent study every pattern that a data transfer inside the application follows regardless of whether it’s dangerous or not.

For example, if data is coming from a user and the user wants to perform an SQL Injection on the application by appending SQL query to a request, then the request will be flagged as dangerous.

What Is RASP

RASP” stands for Runtime Application Self Protection.

RASP is a runtime application that is integrated into an application to analyze inward and outward traffic and end-user behavioral pattern to prevent security attacks.

This tool is different from the other tools as RASP is used after product release which makes it a more security-focused tool when compared to the others that are known for testing.

RASP is deployed to a web or application server which makes it to sit next to the main application while it’s running to monitor and analyze both the inward and outward traffic behavior.

Immediately once an issue is found, RASP will send alerts to the security team and will immediately block access to the individual making request.

When you deploy RASP, it will secure the whole application against different attacks as it does not just wait or try to rely only on specific signatures of some known vulnerabilities.

RASP is a complete solution that observes every little detail of different attacks on your application and also knows your application behavior.

Detect Vulnerabilities Early In SDLC

One good way to preventing defects and vulnerabilities from your application is to build security into the application from the beginning, i.e. all through the SDLC security is paramount.

Never curtail the developer from implementing secure coding, train them on how to implement this security from the very beginning of the SDLC. Application Security is not only meant for the security engineers rather it’s a general effort.

One thing is to build an App that is very functional, fast & performs fantastically well and another thing is for the application to be secure for usage. When conducting architecture design review meetings, include security professionals who will help to conduct a risk analysis of the proposed architectural design.

These reviews will always identify any architectural flaws early in the development process, which can help prevent any delayed releases and also save your organization money and time in finding a solution to an issue that could later erupt.

SAST is a very good security tool that developers can incorporate into their IDE. This is a very good static analysis tool that will help developers to detect any vulnerabilities early even before code compiling.

Before developers compile their code, it is always beneficial to conduct a secure code review session. Code reviews session like this are usually a saving grace and provide the first line of defense against any implementation defects that could cause vulnerability into the system.

Once you can access the source code, use static analysis tools like SAST to detect additional implementation bugs that the manual code review session missed.

Choose Between SAST Vs DAST Vs IAST Vs RASP

If I am being asked to make my choice, I will rather go for them all. But you may ask isn’t it capital intensive?

Anyway, Security is expensive and many organizations shy away from it. They use the excuse of too expensive to prevent them from securing their applications which in the long run could cost them more to fix an issue.

SAST, DAST, and IAST are great tools that can complement each other without any problem if only you have the financial backbone to carry them all. The security experts always support the use of two or more of these tools to ensure better coverage and this will in turn lower the risk of vulnerabilities in production.

You will agree that SDLC is rapidly adopting an agile approach over the years and the usual traditional testing methods cannot keep up with the pace of development.

Adopting the use of automated testing tools in the early stages of the SDLC can significantly improve application security with minimal cost and time.

But note that these tools are not meant to be a replacement for all the other secure coding practices, rather they are a part of an effort to achieve a community with secure applications.

Let’s check some of the ways where these tools are different from each other.



This is a White box testing where you have access to the source code application framework, design, and implementation.

The complete application is tested from the inside out. This type of testing is often referred to as the developer approach.
This is a Black box testing where you do not have access to internal framework that made up the application, source code and design.

The application testing is from outside in. This type of testing is often referred to as the hacker approach.
SAST does not need to be installed rather needs the source code to act.

It usually analyzes the source code directly without executing any application.
DAST needs to be deployed on the Application server and does not need to have access to the source code before acting.

It’s just a tool that needs to be executed to scan the application.
This is one tool that is used to find vulnerabilities very early in the SDLC.

It’s implemented immediately the code is being written. It points out vulnerability in the integrated development environment.
This is only used after the code have been compiled and used to scan the complete application for any vulnerabilities.
This tool is not expensive because the vulnerabilities are usually very early in the SDLC which makes its quicker for the remediation and before the code is placed in motion.This tool is expensive due to the fact that the vulnerabilities are usually discovered towards the end of the SDLC.

Remediation are usually not done real time except on emergency cases.
This tool scans only static code which makes it difficult to discover any run-time vulnerabilities.This tool scan an application by using dynamic analysis to find run-time vulnerabilities.
This supports any applications.This only scans application like web app it does not work with some other software.


This is mostly used as a security testing tool. it looks for security vulnerabilitiesIt’s used not just as a security testing tool but used to protect the entire application by running alongside it. This monitors the application against any attacks.
This support the accuracy of SAST through the use of the run-time analysis results from SAST.This is a tool that identifies and blocks threats in real-time. This activity does not even need any human intervention because the tool lives on the main application and protects it.
It is gradually being accepted and requires the deployment of an agent.It is not yet accepted and requires the deployment of an agent.
There is a limited language support.It’s not language or platform dependent.
This tool is very easy to Integrates for the analysis of source code, runtime control and all the frameworks that made up the application.This tool integrate seamlessly with the application and it’s not reliant on any network-level protections like WAF.
This tool brings out the best from the Combination of SAST and DAST functionality which equally helps it to discover vulnerabilities on a broader scale.Covers a broad range of vulnerabilities

Despite some of the constraints you may observe in technologies like SAST, DAST, IAST, and RASP, using these automated security tools will always guarantee software that’s more secure and save you the high cost of fixing a vulnerability that is discovered later.

Application Security

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Need To Integrate Security Tools Into DevOps

When you combine Development, Operation, and Security together and make them collaborate then you have in essence setup DevSecOps.

With DevSecOps you are able to integrate security into the entire application development process that will help to protect your application against any attack or threat.

DevSecOps is steadily gaining momentum as the rate at which many organizations now turn out applications is alarming. They cannot be blamed for this because the demand is high from customers. Automation is now an essential aspect of DevOps, and there is no difference while integrating security tools into the same process.

Just as every manual process is now being replaced by devops, the same applies to security testing that has been replaced with tools like SAST, DAST, IAST, RASP.

Every security tool that is now a part of any Devops should be able to perform security at a very high level and achieve continuous integration and continuous delivery.

SAST, DAST, IAST, and RASP have been tested by Security architects and are currently establishing high grounds in the DevOps setting. The reason for this is the ease of use and ability of these tools to be quickly deployed into the ever agile world.

Whether the tool is used to perform software composition analysis for vulnerabilities or used to perform an automated code review, the tests should be fast and accurate, and the report should be readily available to the development team to consume.

Frequently Asked Questions

Q #1) What is the difference between SAST and DAST?

Answer: SAST means Static Application Security Testing which is a white box testing method and analyzing the source code directly. Meanwhile, DAST means Dynamic Application Security Testing which is a black-box testing method that finds vulnerabilities at run-time.

Q #2) What is IAST testing?

Answer: IAST means Interactive Application Security Testing that analyzes code for security vulnerabilities while the app is running. It is usually deployed side by side with the main application on the application server.

Q #3) What is the full form of SAST?

Answer: SAST means Static Application Security Testing

Q #4) Which is the best approach or security tool among these four?

Answer: The best approach is usually to have all these tools implemented if your financial power can carry it. By implementing all these tools, you will make your software stable and free from vulnerabilities.


We can now see that the fast pace of our agile environment has now brought about the need to automate our security process. Security is not cheap at the same time security is important too.

We should never under estimate the use of security tools in our day to day development as it will always pre-empt any occurrence of attack into the application. Try as much as possible to introduce it early into the SDLC which is always the best approach to secure your software more.

Thus, making the decision for the right AST solution involves finding the right balance between speed, accuracy, coverage, and cost.