The strenuous task of application security testing (AST) can be done in three different ways. SAST, DAST, and IAST. But how do you decide which method to use? We’ll go over all three types of application security testing, their pros and cons, and how the three differ.
What is SAST?
SAST is known as “Static Application Security Testing”, this type of testing analyzes the application without executing it. This method checks for security vulnerabilities in the source code itself. SAST is mainly used for applications that have already been released and are in use, as it can be difficult to scan an application that is currently being developed.
Pros and Cons of SAST
Pros of SAST:
- detected vulnerabilities are more likely to be fixed, as developers are made aware of them earlier in the development process.
- there is no need for source code access, only the application itself.
- it is more efficient to use against older applications, as it does not require the application’s input.
Cons of SAST:
- False positives can be difficult to handle in this type of testing, as they are critical security issues that require immediate attention but may not exist after further investigation. This causes developers and engineers an unnecessary amount of wasted time.
- This type of testing only checks the code, not how it interacts with other components or systems within your application infrastructure—for example, database servers and third-party APIs. This means that vulnerabilities in these areas may be missed during SAST scans.
- SAST is less effective when used on applications that are still in development, as developers may make changes to the code that invalidate the scan.
What is DAST?
Dynamic Application Security Testing (DAST) occurs when the tester makes use of a tool, such as a web browser or an application emulator, to interact with the live application. This type of testing is used on applications that are still in development and can be executed on both local and remote systems.
Pros and Cons of DAST
Pros of DAST:
- it tests for vulnerabilities that may not be present in the source code, as it is executed against a live system.
- offers security testing of web services and APIs which can be difficult to test for with SAST or IAST.
- DAST can be used to test systems locally as well as remotely.
Cons of DAST:
- false positives are more common than during SAST, as this type of testing makes heavy use of automated tools which may not be perfect.
- can be difficult to use on applications that are heavily reliant on dynamic content, such as those with a lot of user input.
- can be time-consuming, as testers must manually navigate throughout the application to test for vulnerabilities.
What is IAST?
IAST is known as “Interactive Application Security Testing”. This type of security testing is similar to DAST, as it also uses a tool, such as a web browser or an application emulator, to interact with the live application. However, IAST goes a step further and actually injects code into the application in order to test for vulnerabilities.
Pros and Cons of IAST
Pros of IAST:
- like SAST, IAST can be used on applications that have already been released and are in use.
- Also like SAST, IAST detects vulnerabilities early in the development process, as it is executed against a live system.
- like DAST, IAST tests for vulnerabilities that may not be present in the source code and can test web services and APIs via an agent injected into the application itself.
- IAST uses the same testing agent as DAST, allowing it to be more efficient than SAST.
- false positives are less likely due to the use of an agent that allows for monitoring and inspection of the application.
Cons of IAST:
- false positives are more common than during SAST or DAST, as this type of testing makes use of automated tools which may not be perfect.
- can be difficult to use on applications that are heavily reliant on dynamic content, such as those with a lot of user input.
- can be time-consuming, as testers must manually navigate throughout the application to test for vulnerabilities.
Difference between SAST, DAST, and IAST
The distinction between the three sorts of application security testing lies in when they can be performed.
SAST can only be done on applications that are already in use. It primarily analyzes the code to find vulnerabilities.
With DAST, testing can be done on applications that are in use or still under development. It can test for vulnerabilities that may not exist directly within the source code.
Finally, IAST is a combination of SAST and DAST. It is the only type of web security testing that can be done on applications that are already in use and under development. It combines the benefits of both SAST and DAST, as it analyzes both the source code and the live system. IAST uses an agent that is injected into the running application to monitor and inspect it for security vulnerabilities.
Ultimately each type of AST brings its own set of pros and cons depending on what you’re looking for out of an application security test. SAST is good for finding vulnerabilities in the code itself, DAST is good for testing dynamic content and web services/APIs, and IAST is the best of both worlds offering a more complete security assessment.
Conclusion
When it comes to application security testing, it is important to use different approaches during different stages of the software’s development. SAST, DAST, and IAST, each have something unique to offer and come with their own set of pros and cons. The main difference between the three types of application security testing is when they can be performed. Depending on what your goals are, each type of security testing can be beneficial.