What Is SAST? Static Application Security Testing Explained

In our past article, we’ve talked about dynamic application security testing aka DAST – now, let’s talk about its counterpart, which is static application security testing.

SAST is a highly efficient method of testing your application for potential vulnerabilities and issues. While having numerous benefits, it also comes with several limitations – all explained in our article. Scroll down to learn the answer to the “what is SAST?” question and understand why SAST works the best when paired with DAST.

What is static application security testing?

SAST meaning can be defined as a process of testing the application’s source code with an aim to identify vulnerabilities. It is a white-box testing technique, meaning that the person who performs SAST has full access to the application and has comprehensive knowledge about it. 

The main thing to know about SAST testing is that it tests the app’s source code. This allows developers to implement static application security testing at very early stages of development and thus significantly reduce remediation costs. 

Key features included in the SAST definition are:

• White-box testing method
• Investigates the app’s source code
• Can be implemented in early stages of development
• Tests the app in the idle state

How does SAST work?

Now that we are clear about the “what does SAST mean” question, let’s see how it works. To perform static application security testing, you’ll need to use a specialized tool. The most popular options are Klocwork and Checkmarx, both supporting several programming languages. Note that SAST technique is technology-dependent, meaning that the selected tool should support the programming language of your application. We’ll review top SAST tools a bit later, and for now, let’s see how this method actually works.

• Tool selection: you choose a specialized SAST tool based on your tech stack.
• Environment preparation: during this step, you will set up access control and authorization, as well as deploy resources needed for tool implementation.
• Tool configuration: SAST tools can normally be customized in accordance with your needs, so during this step, you will configure it as needed and will integrate it into your environment.
• App onboarding and scanning: once the SAST tool is ready and integrated, you can onboard the apps for scanning and start the process. The tool will automatically investigate the app’s source code, following the configuration rules.
• Results analysis: the tool will provide you with a list of detected vulnerabilities and will sometimes suggest solutions for their remediation. 

As you can see, the process is mostly automated and does not require human interference. Now, you may be asking what kinds of vulnerabilities are present in the source code. Examples include:

• SQL injections
• XXE attacks
• Buffer overflows
• Insecure design
• Vulnerable and outdated components,

And more. To get a better idea of potential vulnerabilities and risks that might be present in your app, see the official OWASP Top 10 list. Static application security testing normally covers the majority of these vulnerabilities, with DAST covering the rest.

Choosing a perfect SAST tool

If you don’t know which SAST tool would work the best for your project, we’ve prepared a short yet comprehensive table that compares the most popular solutions.

The main benefits of SAST testing

With the app’s security being the ultimate goal of any testing activity, SAST code scanning brings several unique benefits to it. Here are the biggest pros of regularly conducting static application testing.

Early detection of threats

As already mentioned, SAST can be used at the beginning of the development process. This allows early detection of potential vulnerabilities and threats and allows developers to remediate them before the app goes into production. Needless to say, this approach greatly increases the app’s security and performance and contributes to a better user experience without any glitches.

Reduced costs

The earlier you are able to detect and remediate a vulnerability, the lower the remediation costs will be. Due to the SAST adoption, you can significantly lower your costs on testing and threat remediation and make sure that your application goes into production in a bug-free state.

Automation

Any testing activity takes time, especially when you need to scan through the entire codebase. Static application security testing is an automated process that scans the app in a highly efficient and quick manner. Not only does SAST scanning save your testing time but also provides accurate results and detailed analysis, which you can later use to improve your app’s security.

Integration with SDLC

Another great thing about a SAST tool is that you can integrate it in the development environment or a build system via a plugin. In this way, the tool will continuously scan the app and immediately notify developers if any vulnerabilities are detected. 

Potential limitations and challenges of SAST scanning

SAST is an integral part of the app testing process, but to maximize its value and ensure that delivered results meet your initial goals, it is important to be aware of potential limitations and challenges. Below, we list the biggest ones.

Does not work in dynamic environments

Since static application security testing covers the app’s source code, it does not test the components of the running app and, thus, can’t detect runtime and compile errors. To ensure the all-round testing of the app, it’s best to combine SAST with dynamic application security testing.

High false positive rate

Because SAST tools do not exploit detected vulnerabilities and work with the source code, there is usually a rather high false positive rate. That means the detected vulnerabilities are identified as suspicious even though they are harmless or pose very little risk. One way to combat this issue is to carefully calibrate your SAST tool – thus, pay attention to its configuration before deployment.

Need for constant updating of reports

Since SAST tests a static environment and is integrated into the development process, the generated reports become outdated really quickly as soon as anything changes in the software. Thus, if you work with SAST, make sure to update the reports and perform testing regularly. Otherwise, you can end up with a pile of new and unidentified bugs and errors that will become more expensive to remediate.

SAST best practices

Lastly, let’s review static application security testing best practices. While the process of SAST implementation will be unique to every organization, a set of processes and methods is applicable to any project.

Implement SAST early

As already stated, early integration of SAST in your SDLC helps reduce remediation time and costs and greatly improves the quality and security of the app due to immediate threat detection. Thus, implement SAST at early stages of the development process to make sure that your code is reliable and secure from the start.

Establish secure coding standards

Secure coding is the process of writing code that adheres to security best practices and follows security principles by OWASP or similar organizations. It is a highly effective preventative measure in battling potential cyberattacks and data breaches and helps maintain universal coding standards across an organization. Paired with SAST and other testing techniques, secure coding is one of the cornerstones of the app’s security.

Regularly test for common vulnerabilities

There is a great variety of potential threats out there, and organizations sometimes focus on not-so-common vulnerabilities, overlooking the common and most obvious ones. However, even the most basic and simple attack can cause great damage. We therefore recommend starting your testing activities by investigating the presence of common vulnerabilities. After ensuring that your app is secured against the most expected threats, you can dig in deeper and test for more specific vulnerabilities and threats, if necessary. 

Summing up

Now that we’ve answered the “what is SAST?” question, we can say the following. Static application security testing is a very effective way to ensure your application’s security – but it can’t provide 100% defense against all potential threats. Thus, you need to use both SAST and DAST alongside other testing methods and test and update the app regularly. Such a holistic approach to testing will yield great results and will help not only prevent but mitigate possible attacks.