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IAST vs DAST: What Is the Difference?

March 7, 2023
Lucjan Zaborowski
What Is DAST?What Is IAST? 
DAST stands for Dynamic Application Security Testing. It is a method of testing the security of a web application by executing it and analyzing its behavior while it’s running. 
Unlike SAST (Static Application Security Testing), which analyzes the source code without executing it, DAST focuses on the application’s runtime environment and how it interacts with the underlying infrastructure, such as the web server, database, and other components.
DAST tools typically simulate attacks against the application by sending requests to the application and examining its responses. This can include injecting malicious data into form fields, attempting to access restricted areas of the application, and other actions that an attacker might take. 
IAST stands for Interactive Application Security Testing. It is a method of testing the security of a web application that combines elements of both SAST and DAST. 
Like SAST, IAST analyzes the source code of an application, but it also executes the code and monitors its behavior in real-time. The goal of IAST is to provide a more comprehensive view of the application’s security posture than either SAST or DAST alone. 
IAST tools typically instrument the application’s code to provide visibility into its behavior, including the data that is being processed and the interactions between components. This information is used to identify security vulnerabilities and provide detailed information about the nature and severity of the issues.

In this article:

How DAST Works 

The basic idea behind DAST is to send HTTP requests to the application and analyze the responses, looking for indications of security issues such as SQL injection, cross-site scripting (XSS), broken authentication and authorization, and other common web application attacks. DAST tools typically automate this process, sending a large number of requests to the application and analyzing the results to identify potential vulnerabilities.

DAST tools can be used to scan entire web applications or specific parts of an application, such as a particular URL or form. They can be run on a schedule, or triggered manually as part of a security testing process.

How IAST Works

In IAST, security testing is performed while the application is running, similar to DAST. However, instead of simply sending requests to the application and analyzing the responses, IAST instruments the application’s code to monitor its behavior in real-time. This allows IAST to provide more detailed and accurate information about potential security vulnerabilities, as it has access to information about the application’s internal state.

The IAST process works as follows:

  1. The IAST tool is integrated into the application, usually by adding a special library or agent to the application’s code.
  2. The IAST tool monitors the application’s behavior as it runs, tracking information such as the input and output of each function, the values of variables, and the flow of control through the code.
  3. When a potential security vulnerability is detected, the IAST tool raises an alert, providing information about the nature of the issue and the location in the code where it was found.

IAST vs DAST: What Are the Differences? 

IAST and DAST are both methods of testing the security of web applications. However, there are some key differences between the two:

Approach

IAST is a hybrid approach that combines both dynamic and static analysis methods. It analyzes the behavior of the application at runtime and also performs a static analysis of the source code. This provides a more comprehensive approach to security testing as it takes into account both the runtime environment and the source code. On the other hand, DAST is a dynamic testing approach that only analyzes the behavior of the application while it is running.

Testing Method

IAST tests the application while it is running, providing real-time analysis of the security vulnerabilities. It monitors the application’s behavior and provides continuous feedback on the security issues it discovers. DAST tests the application by sending various inputs to it and observing how it responds. This approach simulates real-world attacks and identifies vulnerabilities that exist in the application.

Information Gathering

IAST provides more detailed information about security vulnerabilities as it has access to both the source code and the runtime environment. This allows IAST to identify vulnerabilities that are not easily detected through dynamic testing alone. DAST, on the other hand, provides limited information about vulnerabilities as it only has access to the runtime environment.

Performance

IAST may impact the performance of the application being tested, as it runs in real-time and analyzes the application’s behavior. DAST, on the other hand, does not impact the performance of the application, as it only sends inputs to the application and observes how it responds.

Ease of Use

DAST is easier to set up and use, as it requires fewer resources and expertise. It is a good option for organizations that do not have a dedicated security team or the resources to set up and use IAST. On the other hand, IAST requires more resources and expertise to set up and use effectively, as it combines both dynamic and static analysis methods.

In conclusion, both IAST and DAST have their own advantages and disadvantages, and the choice between them will depend on the specific needs and requirements of the organization. A combination of both IAST and DAST can provide a more comprehensive approach to web application security testing. Organizations should consider their security needs, resources, and expertise when deciding which method to use.

Learn more in our detailed guide to dast vs sast.

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Bright Security tests every aspect of your apps. It enables you to scan any target, including web applications, internal applications, APIs (REST/SOAP/GraphQL), and server side mobile applications. It seamlessly integrates with the tools and workflows you already use, automatically triggering scans on every commit, pull request or build with unit testing. Scans are blazing fast, enabling Bright to work in a high velocity development environment.

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