Difference between SAST and DAST

Static Application Security Testing (SAST) and Dynamic Application Security Testing (DAST) are two critical approaches to application security testing. While both aim to identify vulnerabilities, they do so in different ways. SAST analyzes the source code or binaries of an application without executing it, making it effective for finding vulnerabilities early in the development process. On the other hand, DAST tests the running application from an external perspective, identifying vulnerabilities that may only be apparent during runtime.

Understanding the differences between SAST and DAST helps in choosing the right approach to ensure comprehensive security for your applications.

What is Static Application Security Testing (SAST)?

It is a type of white box testing method meaning they require access to source code to function. It finds all security vulnerabilities including software flaws and weaknesses such as SQL injection and others by examining code before it is deployed. SAST does not require a running system to perform evaluations. 
Static Application Security Testing (SAST) is a highly scalable security testing method. It can be automated also which will help in saving time and money. SAST testing is performed early in the Software Development Life Cycle (SDLC), so it is easy to find potential security vulnerabilities earlier.

Advantages of SAST

• Early Detection: SAST helps in finding out security flaws at the initial level of the SDLC which makes it much cheaper and easier to eradicate them as compared to the latter stages of the SDLC.
• Comprehensive Code Coverage: It reviews the entire code and the branches starting from the basic functions and right up to the complex ones thus leaving no part of the code unchecked.
• No Need to Run the Application: SAST operates on the source code, hence, the application does not have to run at the point of testing making it appropriate for the early stages.

Disadvantages of SAST

• High False Positives: It was ascertained that SAST tools can create a large number of false positives, which in turn increase the number of check-ups performed manually.
• Limited Detection of Runtime Issues: But as mentioned, SAST does not discover the problems that happen at the real use of the application, for example, configuration mistakes or runtime environment susceptibilities.
• Less Effective for Complex Environments: It may have difficulty identifying problems in applications that are use cases that require functions that are only discernible at runtime such as multi-threading or even dynamic dependencies.

What is Dynamic Application Security Testing (DAST)?

It is a type of black-box testing method which means that tests are performed from outside a functioning application rather than viewing into internal source code or application architecture. It is running to find a broad range of vulnerabilities by examining application. DAST requires a running system to perform evaluations. 

Different security vulnerabilities that are linked to operational deployment of a software application can be determined through Dynamic Application Security Testing (DAST). In DAST, testers perform actions similar to an attacker so that it helps in finding out different security vulnerabilities that may be missed by other testing techniques.

Advantages of DAST

• Runtime Detection: DAST focuses on the issues that can be found only during the execution of the application, for instance, in the runtime environment there may be certain weaknesses, or the application is configured improperly.
• No Access to Source Code Required: Another is that DAST operates outside of the application, and this makes it effective if used in testing third party applications, or compiled code where one has no access to the source code.
• Real-World Simulation: This process emulates the actual attack scenarios and engage with the application hence assist in the identification of risks that SAST may leave out.

Disadvantages of DAST

• Limited Code Coverage: DAST tests are still limited and only focus on the outer layer of the application and may fail to reveal the weaknesses that might be hiding in the other layers that were not tested.
• Slower in Identifying Issues: As DAST is normally applied in the later stages of SDLC or at the production stage, fixing the vulnerabilities might be expensive and time consuming.
• False Negatives: Still, it is possible that DAST could not identify vulnerabilities that could be seen only during direct analysis of source code (as in the case of SAST).

Difference between Static Application Security Testing (SAST) and Dynamic Application Security Testing (DAST)

Conclusion

In summary, SAST and DAST serve distinct but complementary roles in application security. SAST provides early detection of vulnerabilities by analyzing the code before execution, while DAST identifies issues that occur in the running application. By leveraging both SAST and DAST, organizations can achieve a more thorough security assessment, addressing potential vulnerabilities from both code and runtime perspectives.

This combined approach enhances the overall security posture and resilience of applications.