Application Security Testing Methods and How They Differ: SAST, DAST, and IAST

Application security testing (AST) can be of different kinds, and knowing which one to use may be difficult. In this blog post, we will discuss the three most common types of application security testing: static application security testing (SAST), dynamic application security testing (DAST), and interactive application security testing (IAST). We will explain the differences between these three types of testing, their pros, and cons, and help you decide which type is best for your needs.

Types of Application Security Testing Methods

SAST

This is a type of application security testing that analyzes source code for potential vulnerabilities. SAST tools examine the code itself, rather than how the code is executed. This makes SAST an ideal choice for applications that are in development or have not yet been released to the public. Static analysis can identify issues such as coding errors and insecure configurations, but it cannot detect issues that occur during runtime.

SAST Pros:

• SAST tools can help you find flaws in your code as and when you’re working on it
• Many SAST tools allow integrations with most coding platforms such as GitHub, Eclipse, etc.
• It is more accurate and reports fewer false positives

SAST Cons:

• Since it does not test applications during runtime, it can miss critical vulnerabilities
• Doesn’t look for flaws after deployment

DAST

This is a type of application security testing that tests an application while it is running. DAST tools use automated scanners or manual testers to simulate attacks on the live application. This allows DAST to find vulnerabilities that may only be exploitable when the application is running. However, since dynamic application security testing (DAST) does not have access to the source code, it cannot identify issues that occur during compile time.

DAST Pros:

• DAST can find vulnerabilities that only occur during runtime
• It can test applications that are already deployed
• It’s effective in finding high-level vulnerabilities

DAST Cons:

• Can take up more time
• May cause the application to crash during testing
• Not as accurate as SAST as it may report quite a few false positives.
• Since DAST tools do not have access to the source code, they cannot identify issues that occur during compile time.
• It’s more challenging to employ on apps that need a lot of user input as it can be difficult to automate

IAST

This type of application security testing is much like DAST as it is performed on applications that are running. However, it goes a step further and “interacts” with the application while testing. This can include fuzzing, injecting code into the application, testing with different inputs, etc. IAST tends to be more accurate than DAST, as it detects flaws based on the application’s response to the inputs given. It’s also just as good as DAST in detecting issues that occur during runtime.

IAST Pros:

• IAST is more accurate than DAST, as it detects flaws based on the application’s response to the inputs given.
• It can detect issues that occur during runtime
• IAST is just as good as DAST in detecting issues that occur during runtime

IAST Cons:

• Can be more difficult to set up
• Takes more time than SAST or DAST
• May require more technical expertise than SAST or DAST

SAST vs. DAST vs. IAST:

In short, SAST tests an application’s source code while DAST tests an application while it is running/in its live environment. IAST tests applications by interacting with them with various inputs and analyzing the application’s response to them.

So, what’s the best type of Application Security Testing (AST) for your needs?

The answer to that depends on what type of application you’re testing, how much of it has been developed, and the goal of the test.

• If you’re looking for a way to find coding errors and insecure configurations in your code, SAST is the best option for you.
• If you’re looking for a way to find vulnerabilities that occur during runtime, DAST is the best option.
• And if you’re looking for a more accurate and in-depth assessment of your application’s security, IAST is the best option.

However, keep in mind that no single type of application security testing can provide a complete view of an application’s security posture.

Conclusion

Application security testing is vital and crucial for ensuring safe and secure applications are put out in the world.

As a matter of fact, there are other two application testing methods that we omitted but are open to discussing in the future; Software Composition Analysis (SCA) which acts differently from the others, it monitors open-source, third-party libraries, for vulnerabilities in all types of mobile or web applications, and Penetration Testing (pen test) is the reliant on human agent to assess the application’s architecture, components, and code libraries by simulating an attack.

SAST, DAST, and IAST are three different types of application security testing methods with their own strengths and weaknesses. Choose the right type of AST for your needs or use all three in conjunction to get the most comprehensive view of your application’s security posture.

Author Bio-

Ankit Pahuja is the Marketing Lead and Evangelist at Astra Security. Ever since his adulthood (literally, he was 20 years old), he began finding vulnerabilities in websites & network infrastructures. Starting his professional career as a software engineer at one of the unicorns enables him in bringing “engineering in marketing” to reality. Working actively in the cybersecurity space for more than two years makes him the perfect T-shaped marketing professional. Ankit is an avid speaker in the security space and has delivered various talks on top companies, early-age start-ups, and online events.

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