SAST stands for static application security testing. It is otherwise known as static analysis. This testing methodology analyses source code and discovers vulnerabilities in the security infrastructure. By uncovering these weaknesses, companies can identify the susceptible areas in code.

SAST solves problems early on during the software development life-cycle. Fortunately, no working application is required. SAST occurs without any code being executed on the company's part, and it's a powerful tool developers use to rapidly identify the vulnerabilities that could upend the entire system.

The tools provided by SAST offer developers instant feedback while they are busy coding. It also helps to identify anomalies, repair errors, and make necessary changes in double-quick time. This is especially important in a multiphase system with problems typically passed on down the line. As a result, SAST can solve many issues before they get passed along. It's also ideal to provide graphical illustrations of any problems discovered. This makes it much easier to navigate coding since several SAST tools can pinpoint the precise location of these weaknesses, highlight problematic code, and give the proverbial heads-up to software developers to fix these issues.

As a security activity, SAST is indispensable. It is a well-known fact that developers outnumber security personnel at companies. It's tough for companies to cobble together the resources to review source code, correct errors, and maintain the efficient and effective functioning of the system. Too many applications, too much code, and too much risk are involved.

One core tenet of SAST is its ability to analyze all code bases effectively, scan the entire source code, and instantly identify vulnerabilities. Such is the advanced nature of SAST that it's capable of automatically pinpointing critical weaknesses, noteworthy among them CSS (cross-site scripting), SQL injection, and buffer overflows.

What about IAST?

IAST also analyses code and identifies security flaws. It stands for Interactive Application Security Testing. IAST is typically conducted via automated testing while the app is being run. This type of technology reports on the vulnerabilities in real-time. This is important since it doesn't add time to the CI/CD pipeline.

Since it works inside the application, it differs substantially from other testing systems, such as dynamic and static analysis security testing. Further, it is limited in scope. It tests only whatever is exercised by the functional test, not the entire application or codebase.

There are certain advantages to IAST. These include instant reporting of findings in real-time. But this is restricted to the app being exercised. The fact that it's an automated test makes it a good fit for API testing, particularly for teams building microservices. Additionally, IAST is effective at promoting the reuse of existing tests.

This means there is no need to recreate scripts for security testing. Overall, IAST is best suited as a complementary security solution. In other words, it is used with other technologies. Many companies require developer-centric security solutions and security assurance solutions.

What is Better: SAST or IAST?

If your company needs to identify insecure constructs and data flows, SAST is sacrosanct. It's also known as white box testing. With SAST, you get to see inside the application. This is ideally suited to the developmental stage of source code testing. It is used before a prototype is up and running. Of course, there are many variants of SAST. Note that SAST resources are typically restricted to programming languages. If there is a multi-language code base, additional tools may be required. But, there are many pros to using SAST, notably checking an entire codebase, even code that's not currently being used. It's ideal for static code without running applications, and it's fairly easy to insert into IDEs during the developmental processes.

IAST works while the application is running. However, IAST monitors the application's code in real-time. This feature makes it a detailed and accurate tool to identify security weaknesses. Typically, this tool is used in the application. The developer may need to integrate an agent or a special code library into the code.

The tool checks the application's behavior while it is running. Tracking is undertaken, with all sorts of metrics compiled. Once an anomaly, a threat, or a flaw is discovered, the tool alerts the developer with important information about the problem's nature and the source code's location. Remember, though, that IAST is programming language-dependent. It's a major Achilles heel since many tools don't require a code change.