Updated on 07/18/2024

Static Application Security Testing (SAST) has been a central part of application security efforts for more than 15 years. According to the Crowdstrike 2024 State of Application Security Report, eight out of the top 10 data breaches of 2023 were related to application attack surfaces, so it’s safe to say that SAST will be in use for the foreseeable future.

What is SAST?

Static application security testing (SAST), one of the most mature application security testing methods in use, is white-box testing, where source code is analyzed from the inside out while components are at rest. Gartner’s definition of SAST is “a set of technologies designed to analyze application source code, byte code and binaries for coding and design conditions that are indicative of security vulnerabilities.”

Why do we need SAST?

With application-level attacks on the rise and delivery schedules only getting shorter, it’s important to have SAST’s insights on potential vulnerabilities in newly written code early and often in the development process. SAST can also be run on older code so security debt can be prioritized and addressed.

What problems does SAST address?

SAST enables developers to detect security flaws or weaknesses in their custom source code. The objective is either to comply with a requirement or regulation (for example, PCI/DSS) or to achieve better understanding of one’s software risk. Understanding security flaws is the first step toward remediating security flaws and thus reducing software risk.

How does SAST work?

As its name implies, SAST scans organizations’ static in-house code at rest, without having to run it. SAST is usually implemented at the coding and testing stages of development, integrating into CI servers and, more recently, into IDEs.

SAST scans are based on a set of predetermined rules that define the coding errors in the source code that need to be addressed and assessed. SAST scans can be designed to identify some of the most common security vulnerabilities out there, such as SQL injection, input validation, stack buffer overflows, and more.

Demystifying SAST, DAST, IAST, and RASP

A number of tools exist to test or protect applications throughout the software development lifecycle (SDLC). SAST, DAST, IAST, and RASP are sometimes confused with one another. We’ll briefly go over them here and in the next section we’ll go deeper into the differences between SAST and DAST.

• Static Application Security Testing (SAST) looks for weaknesses in custom code at rest
• Dynamic Application Security Testing (DAST) performs automated attacks on applications to test them for weaknesses when they are running
• Interactive Application Security Testing (IAST) combines DAST capabilities with SAST insights
• Runtime Application Self-Protection (RASP) is built into a program to protect it after deployment. It is capable of detecting and preventing external threats in real time.

What is the difference between SAST and DAST? 

SAST is one of the primary application security testing methodologies that are available, alongside DAST (dynamic application security testing). So, what’s the difference and which should you choose?

SAST and DAST differ in how and when they perform security testing and their access to source code. SAST is known as a “white-box” testing method that tests source code and related dependencies statically, early in the SDLC, to identify flaws and vulnerabilities in the code that pose a security threat. It is used to ensure that developers take care when writing their code. SAST tests applications from an internal perspective. SAST tools are easy to integrate into CI/CD pipelines and make it cheaper to locate and fix issues before they get complicated by being on software that’s functioning and in applications that are running. However, it requires visibility into and knowledge of the code being used and tested. 

DAST takes the opposite approach to SAST. It is known as “black-box” testing, which means the code is tested while it’s running, without any knowledge of or access to the source code. It is concerned with identifying runtime issues and weaknesses in software and applications. DAST testing is performed later in the SDLC, when software and applications are actually working. While SAST tests the code from the inside out, DAST tests it from the outside in, taking a hacker’s rather than a developer’s perspective. Rather than being static, DAST is dynamic, because it tests as applications run, so it needs a working version of the application for it to perform testing.

SAST and DAST complement each other. Therefore, implementing both will help you optimize and maximize your software and application security, by providing ways of scanning your software at any point in the SDLC.

Typical SAST benefits

SAST is a top application security tool and, when done right, is essential to a robust application security strategy. Integrating SAST into the SDLC provides the following benefits:

Shifting security left. Integrating security testing into the earliest stages of software development is an important practice. SAST helps shift security testing left, detecting vulnerabilities in proprietary code in the design stage when they are relatively easy to resolve. Finding and remediating security issues at this stage saves organizations the costly efforts of addressing them closer to the release date or, even worse, after release.

Ensuring secure coding. SAST easily detects flaws that are a result of fairly simple coding errors, helping development teams make sure that they comply with secure coding standards and best practices.

Detecting common vulnerabilities. Automated SAST tools can easily detect common security vulnerabilities like buffer overflows, SQL injection, cross-site scripting, and more with high confidence.

Enhanced benefits of next-generation SAST

SAST is a mature technology and the application development environment has changed since it was introduced. The new generation of SAST products have evolved in response to these changes, particularly the scale and rapidity of the modern environment. This evolution offers the following additional benefits that enhance those offered by previous SAST products:

Ease of use. The new approach to SAST further integrates it with your existing DevOps environment and CI/CD pipeline, so developers don’t need to separately configure or trigger scans. This removes the need for them to leave their development environment to run scans, view results, and research how to fix security problems. It’s more efficient, convenient, and easier for them to use. 

Comprehensive CWE coverage. The comprehensive detection provided by Mend SAST provides visibility to more than 70 CWE types — including the OWASP Top 10 and SANS 25 — in desktop, web, and mobile applications developed on various platforms and frameworks. 

Support for multiple programming languages and programming frameworks. For example, Mend SAST supports 27 different languages. This enables more comprehensive vulnerability detection and increases the visibility to a larger number of CWE types.

Overcoming false positives and eliminating wasteful effort. Older SAST products typically generated a high number of false positives, costing development and security teams significant time and effort differentiating between false alarms and real issues. Considering the competitive pace of development and the amount of time it takes to remediate critical issues, dealing with the noise of false positives puts quite a strain on development. Now, Mend has a patented set of analytics that enables teams to significantly reduce the generation of false positives that they would otherwise have to sift through.

Speed. Traditional SAST solutions were designed for an earlier era, when the typical SDLC took considerably longer than it now does, and one scan could take several hours for a large code base. In today’s fast-paced development environment, where the duration of a release cycle is less than a day, these products are a poor fit. Numerous research studies have shown that many developers simply don’t use the application security tools that their security team provides, because they choose speed over security. The new Mend SAST has a scan engine that is 10 times faster than traditional SAST products, so your engineers will get results in minutes or less.

SAST Pros and Cons

SAST Benefits	SAST Limitations
Early Detection Finds vulnerabilities early in the SDLC	Later Detection Does not find and mitigate flaws and vulnerabilities later in the SDLC or when development is complete
Fast Faster to remediate vulnerabilities early in the SDLC	Static Code Only Not dynamic. Doesn’t discover runtime flaws and vulnerabilities
Simple Fast, early detection makes it easier to fix code before it enters the QA cycle	Requires Source Code Needs access to the source code to work
Versatile Supports all kinds of software and application (web, desktop, mobile)	Custom Code Only Designed to support custom code, not open-source software and dependencies
Cost-Effective Early detection makes remediation easier, less time-consuming, and therefore, cheaper	False Positives Traditional SAST tools can generate many false positives, which can hamper development

Legacy vs. Modern SAST tools

A new generation of SAST solutions lets enterprise application developers create new applications quickly, without sacrificing security. They aim to integrate with your existing DevOps environment and CI/CD pipeline, so developers don’t need to separately configure or trigger the scan. They expedite the SAST process, while supporting multiple programming languages and various different programming frameworks.

Modern SAST tools that include these capabilities increase efficiency and convenience for developers. They make it quicker and easier to detect vulnerabilities, and they ensure compliance and reinforce governance. As a result, developers will learn to trust their software tools and collaborate more readily with members of the security team.

How to choose the right SAST tool for your organization

The AST market is full of SAST offerings, often bundled up with additional solutions, making it a challenge to find the right fit for your organization.

OWASP’s list of criteria for selecting the right SAST tools can help companies narrow down the options and choose the solution that best helps them improve their application security strategies.

• Language support. Make sure the SAST tool that you use offers you complete coverage for the programming languages your organization uses.
• Vulnerabilities coverage. Make sure that your SAST tool covers at least all of OWASP’s Top Ten web application security vulnerabilities.
• Accuracy. Your SAST solution should be capable of minimizing the false positives and false negatives that create unnecessary work. So, it’s important to check the accuracy of the SAST tools that your organization is considering.
• Compatibility.  Like any automated tool, it’s important that the SAST tool you use is supported by the frameworks you are already using so that it integrates easily into your SDLC.
• IDE integration. A SAST tool that can be integrated into your IDE will save you valuable remediation resources.
• Easy integration. Find the SAST tool that is easy to set up and integrates as seamlessly as possible with the rest of the tools in your DevOps pipeline.
• Scalability. Make sure the SAST tool you integrate today can be scaled to support more developers and projects tomorrow. A SAST tool can seem to scan quickly on a small sample project; make sure it delivers similar results on larger projects.

Rising scale can also impact the cost of the solution. OWASP’s list points out that it’s important to consider whether the cost varies per user, per organization, per application, or per line of code analyzed.

How to Implement SAST

Having chosen your SAST solution, it’s important to implement it correctly in order to optimize its effectiveness and maximize the benefits you get from it. Successfully achieving this involves the following steps:

Select the means of deployment. Decide whether you will deploy SAST on-premises or in cloud environments. This consideration depends on how much control you wish to have and how quickly, how easily, and how much you might wish to scale up.

Configure and integrate into your SDLC. Considerations here include when and how you scan and analyze your code. You can elect to:

• Analyze code as it’s compiled
• Scan it as you merge it into your code base
• Add SAST in your CI/CD pipeline
• Run SAST in your IDE, enabling developers to detect and mitigate vulnerabilities as they code

Choose the extent of your analysis. You can decide between the following:

• Complete: A full scan of your applications and their code is the most comprehensive and most lengthy process
• Incremental: Scan only new or changed code
• Desktop: Code scanned as it’s written, with issues addressed in real time
• Without build: Analysis in the source code, for those not familiar with the building process or the IDE

Customize to suit your needs. You might want to focus on reducing false positives, creating new rules, or revising old ones in order to identify new security flaws. Perhaps you want to create dashboards for analyzing scans, or build custom reports.

Prioritize applications and results, based on what’s most important to you. Considerations include compliance issues, severity of threat, CWE, risk level, responsibility, and status of the vulnerability.

Analyze results, track progress, and evaluate urgency. Examine scan results to remove false positives. Set up a system that automatically sends issues to the developers responsible, and then assign them to be addressed.

Report and governance. Use either built-in reporting tools such as OWASP Top 10 violations, or push data to other reporting tools you already have. Ensure that development teams are using the scanning tools properly.

SAST: An important component in your application security journey

Using traditional SAST products to ensure security in application development requires a value tradeoff. And that tradeoff is speed. SAST offers high value when it comes to coverage and visibility over an organization’s static code base. It also integrates early in the SDLC, enabling organizations to shift security left. But, traditional solutions present major barriers to agility.

The next generation of SAST overcomes these barriers to meet the demand of today’s rapid SDLC. As the SDLC becomes shorter and shorter and as more applications are developed, the attack surface grows and the risk to the application layer continuously rises. However, now, the need to make such a value tradeoff is significantly reduced.

Successfully integrating SAST requires organizations to find the right balance between minimizing risk by covering all security vulnerabilities and delivering quality products at a competitive speed. Now, development teams can more confidently combine security and speed earlier than ever in the development process.

FAQs

SAST should be deployed early in developers’ workflow when they design and write applications and before applications go into production. This allows developers to detect and remediate flaws in software components and dependencies before they go into production.

Various industry standards recommend that organizations scan and assess their code regularly. In the interests of thoroughness, and to meet different compliance requirements, it’s advisable to do this at least monthly. However, scanning and assessment should really be performed whenever changes are made to existing code, software, or applications, or whenever new components and dependencies are introduced. This will keep your security up-to-date and ensure that new flaws and vulnerabilities are identified and stopped from entering your code base. Of course, if you scan more frequently, it’s more likely that you’ll identify flaws and mitigate any threats quickly and earlier.

It’s also important to perform vulnerability scanning in line with the following industry compliance standards:

• Payment Card Industry (PCI DSS) – Quarterly
• National Institute of Standards and Technology (NIST) – Quarterly to monthly depending on governing framework
• Cyber Security Maturity Model Certification (CMMC) – Weekly to quarterly based on auditor requirements
• Health Information Protection Accountability Act (HIPAA) – Scanning not required but states a detailed assessment process must be established.

SAST should be deployed early in the implementation phase of the SDLC. because they don’t need a running application to perform an analysis. Security teams therefore use SAST tools to scan applications during the coding process and before production.

Yes. SAST is designed to specifically analyze source code, and compiled versions of code to help detect vulnerabilities and issues during software development.

*** This is a Security Bloggers Network syndicated blog from Mend authored by AJ Starita. Read the original post at: https://www.mend.io/blog/sast-static-application-security-testing/