Static Application Security Testing (SAST) Scanning

Key takeaways: Why SAST matters

• The majority of vulnerabilities originate in source code.

• SAST supports compliance frameworks such as PCI DSS, HIPAA, and ISO 27001, which require secure development practices.

• SAST empowers teams to build security directly into the SDLC, rather than treating it as an afterthought

• Choosing the right Static Application Security Testing (SAST) tool requires balancing coverage, accuracy, and developer workflow. 

• Modern AI-native SAST tools like Snyk leverage machine learning and large language models to enable detection of complex vulnerabilities that rule-based scanners often miss. 

Static Application Security Testing (SAST), also known as static code analysis or white-box testing, is one of the most effective ways to identify vulnerabilities early in the software development lifecycle. Every year, insecure code contributes to thousands of data breaches

— but by scanning source code before it’s deployed, teams can catch flaws before they become costly security incidents.

Why is SAST important for application security?

Every developer's goal is to keep their source code secure without overthinking it. But developers often don't have the security background to avoid insecure programming patterns, know how to use secure APIs, or detect interfile issues that include several parts of an application not developed by a single team. 

SAST analyzes your source code for security vulnerabilities, so you don't have to. Integrating SAST early in your continuous integration (CI) pipeline or into the integrated development environment (IDE) using a plugin while coding enables the tool to check your code in real-time and prevent security issues from entering the codebase.

Unlike dynamic testing (DAST), which finds issues in a running application, SAST identifies weaknesses during development — enabling developers to fix flaws early, when remediation is faster and less expensive.

7 stages of a security application testing scan

The seven stages of a SAST scan are:

7 Stages of Static Application Security Testing (SAST)

1. Continue coding while integrating security into the development process to prevent vulnerabilities from being introduced in future code. Embedding security into every stage includes: code reviews, merging practices, branching policies, secure coding guidelines, and compliance controls. Also monitor new threats, evolving rule sets, and tool upgrades. Remember to scan not just new code but refactored legacy code continuously.

2. Scan your code as it’s being written with real-time or near-real-time static analysis (IDE, pre-commit hooks, or early CI pipelines). This includes checking syntax, style violations, insecure API usage, and coding patterns known to be risky (e.g., unsanitized input, hard-coded secrets, weak cryptography).

3. Prioritize and triage based on the severity and impact of the vulnerabilities found. Once issues are detected, classify them by severity (e.g., CVSS or internal scoring), exploitability, impact to the application & business, exposed attack surface, whether they are reachable, etc. Triage also involves filtering out false positives or noise, so effort is focused on meaningful risks.

4. Understand the nature of the vulnerabilities found by reviewing scan data and assessing the associated risk level. Deep dive into each identified issue to understand the root cause, the data flow, control flow, and dependency interactions. Determine what risk the vulnerability actually poses in the deployment environment.

5. Learn from the scan findings to prevent similar vulnerabilities in the future. This includes: integrating secure coding standards, educating developers, updating code review checklists, and refining scanning rules. Implement policies so that common mistakes are less likely to recur. Possibly run secure peer reviews, coding workshops, or include training on new vulnerability classes.

6. Fix vulnerabilities found in the scan by patching the code or implementing other remediation measures. Remediation could involve modifying code, removing or replacing vulnerable libraries, altering configurations (e.g., input validation, output encoding), or even re-architecting modules. For some issues, mitigations are acceptable, for others, full fixes are needed. Fixes must be thoroughly tested to ensure they don’t break functionality or introduce new issues.

7. Rescan to verify that the fix has worked. After remediation, trigger a fresh SAST pass—either on the changed area (incremental) or the whole codebase (baseline)—to ensure that vulnerabilities are resolved and no unintended side effects or new issues arise. Validate that any threat path is closed.

7 Stages of SAST — Key Technical Points & Best Practices

SAST implementation best practices checklist

• Define & document roles & ownership

• Start scanning early & often (Shift-Left)

  • Integrate SAST in IDE or pre-commit hooks so developers get feedback as they code

  • Run scans on pull requests/feature branches automatically

  • Schedule full baseline scans periodically (e.g., nightly, weekly)

• Tune rulesets & configurations

  • Customize rule sets for your language/framework / architecture

  • Set severity thresholds (critical, high, medium, etc.) clearly, so policy can enforce gates for critical/high issues

• Prioritize & triage findings intelligently

  • Use metrics like exploitability, business impact, exposure, and whether code paths are reachable

  • Maintain a triage process/rubric so issues are categorized consistently

  • Ensure findings are assigned to owners, with SLAs for remediation (e.g., critical issues must be fixed within X days)

• Integrate into CI/CD pipelines with quality gates

  • Add SAST in build steps/pull requests so code with certain vulnerabilities can be prevented from merging/deploying

  • Implement incremental/differential scanning for changed code to improve speed and feedback loop

  • Configure the CI/CD tool to flag/fail builds for critical severity or threshold exceedances

• Provide effective feedback & remediation guidance

  • Reports with file paths, line numbers, context), exploitability, suggested fixes

  • Integrate feedback into the environments developers work in 

  • Maintain documentation or internal knowledge base of common vulnerability patterns & mitigations

• Manage false positives & tool maintenance

  • Review false positives & false negatives regularly

  • Keep SAST tool and rule database/detection engine up-to-date to cover latest attack vectors

  • Ensure the tool supports all languages/frameworks/build systems used in your organization

• Monitor, measure & improve over time

  • Define and track KPIs: time to remediate, vulnerability density, false positive rate, trends by severity class

  • Perform periodic audits of scan coverage and rule effectiveness

  • Use scan data to feed developer training and updates to coding standards

• Align with compliance, threat models & risk context

  • Map SAST findings to risk models and threat profiles for your specific domain/application environment

  • Ensure scan results are usable for compliance (e.g., reporting, proof, traceability)

  • Consider regulatory frameworks & standard bodies (e.g., OWASP, CWE, NIST SSDF) when selecting rules & defining policy

• Optimize performance & developer experience

  • Use incremental scans for faster feedback in PRs / commits

  • Exclude irrelevant code (e.g., generated code, test files, vendor or third-party libraries that are stable or patched) when appropriate

  • Balance depth vs speed (e.g., quicker feedback in early stages, deeper scans in scheduled or release builds)

5 benefits of static application security testing

SAST offers numerous benefits for the software development lifecycle (SDLC), like improved code quality and reduced overall cost and effort to ensure application security.

Here are five benefits of implementing SAST:

1. Scans early in development: Most SAST tools work solely on source code, checking it against best practices. This means SAST can be applied while writing your code. IDE plugins for SAST tools are common and catch problems before anything enters version control. This is especially important when using AI coding tools, which, by the very nature of their technology, can introduce errors and hallucinations into code at hitherto unseen speeds.

2. Indicates problematic code locations and explains the issue found: SAST shows you the exact location of every vulnerability and explains the data flow. This makes it simple to understand and remediate each one.

3. Requires no test cases: Some AppSec tools, like dynamic application security testing (DAST), require you to decide what to test, while SAST tools will simply apply all their rules to your codebase.
   These rules can be manually implemented by the SAST tool creator or the community. These rules are often based on numerous projects and years of programming experience, meaning a rule developer must be knowledgeable in different fields. These rules allow you to catch vulnerabilities you didn't even know existed.

4. Requires no app execution: SAST works on the source code before the application runs; therefore, SAST scans are much quicker than other application testing suites.

5. Easy to automate: Source code files can be scanned automatically at any point of the SDLC. This means SAST can be used as a security gateway at any point.

3 limitations of SAST (and how to overcome them)

Despite the benefits, static application security testing also has limitations, including the inability to detect certain vulnerabilities. Other major SAST limitations include:

• False positives and false negatives: SAST tools interpret the source code and need to apply certain assumptions. This might lead to SAST tools finding issues that are not true which is called a false positive — a false finding. Legacy SAST tools could have a 50 to 80% false positive rate, making it hard to find the signal in the noise and the ROI on SAST questionable, so it's important to use a modern SAST  that delivers better accuracy, both through streamlined and prioritized findings, and through customizable features.

• Missing context: Unsanitized user input is a huge security risk and should be fixed whenever entering a software component. Unsanitized input on the front end is often fixed on the backend, mitigating the risk. This happens because frontend and backend code aren’t always in the same repository, meaning that a SAST tool won’t detect the sanitation and prompt the developer to fix a non-issue.

• Language dependency: SAST has a strong code dependency. Plenty of SAST tools are available for prevalent programming languages (e.g., Java and C#), but for more niche languages (e.g., ReScript and Nim), there are very few SAST tools out there.

SAST vs. other AppSec tools

SAST vs. other AppSec tools

Several tools are available for application security, so it's critical to understand the differences between SAST and other application security testing tools to determine which is the best fit for your organization. The right mix of AppSec tools can help your organization catch code-level flaws early, validate runtime vulnerabilities later, and combine strengths to build a resilient security posture.

SAST vs DAST vs SCA

SAST vs. DAST

If SAST is white-box testing, then DAST is a black-box testing method. DAST tests applications in runtime and is applied later in the CI pipeline. DAST is a good method for preventing regressions, and unlike SAST, it is not programming language-specific.

Fuzzing is a DAST method that stresses an application to cause unexpected behaviors, crashes, or resource leaks. This allows developers to understand the behavior and vulnerabilities of the application comprehensively.

Read more about SAST vs. DAST, the difference, and how to combine the two for optimal results.

SAST vs. IAST

Interactive application security testing (IAST) is a newer approach to application security testing that provides real-time feedback on potential vulnerabilities in an application.

IAST is considered very accurate, as it combines elements of SAST and DAST and provides visibility into the code and the application runtime environment.

The interactive nature of IAST also allows for more efficient remediation of vulnerabilities, as developers are provided with specific details about the issue and can address it directly within their workflow.

SAST vs. SCA

Software composition analysis (SCA) focuses on third-party code dependencies in the application. It discovers more details about open source components than SAST can, such as licensing details and version history — making SCA a better fit for securing third-party dependencies. 

SCA is very effective in applications that use many open source libraries, it’s common practice to use a lot of open source libraries during development, so SCA is becoming more important than ever, but this method is also programming language-dependent.

Read more about SAST vs. SCA and how to combine them to release secure software.

SAST and other AppSec tools

SAST, DAST, SCA, and IAST are all essential application security testing types that offer different perspectives on the security posture of the development lifecycle.

These tools complement each other, so employing them together will give you a comprehensive assessment of your application's security.

How do SAST tools work, and how do you choose one?

SAST is a technique used to evaluate source code without actually executing it. It involves examining the program's structure and syntax to identify potential issues and errors, such as coding mistakes, security vulnerabilities, and performance bottlenecks. The process involves parsing the source code, building an abstract syntax tree, and applying various analysis techniques to detect issues. By providing early feedback on potential issues in the code, SAST can help improve software quality and reduce the likelihood of errors and security vulnerabilities.

5 SAST Analysis Types

What vulnerabilities can SAST tools find?

SAST tools detect a range of security incidents and vulnerabilities in source code, including: 

• Dataflow issues 

• Semantic errors 

• Misconfigured settings

• Control flow problems 

• Structural flaws

• Memory issues

How can SAST be used to automate cloud security testing?

SAST can automate cloud security testing by integrating directly into CI/CD pipelines, ensuring vulnerabilities are detected and addressed before deployment. By continuously scanning source code for security flaws, SAST helps maintain compliance with cloud security best practices and prevents misconfigurations that could expose cloud environments to threats. With developer-friendly automation, modern SAST tools like Snyk Code enable real-time scanning and rapid remediation, reducing the risk of security issues slowing down development.

How to find the right SAST tool to secure the software development lifecycle (SDLC)

SAST is a crucial part of securing the software development lifecycle, so it is essential to choose a tool with certain features, like:

• Developer-friendly features, like real-time scans and auto-fixes across different environments, and an interface with a UI that is easy for non-security staff to use and understand. 

• Fast scanning capabilities to avoid slowing down the development process.

• Reporting capabilities that allow teams to prioritize the high and critical-severity issues that they need to fix.

• Automatic remediation (or “auto-fixing”) capabilities, so that developers can apply accurate vulnerability fixes with one click and know that these fixes will not cause new security issues in their code.

• Low false positive rates, as this reduces the time and effort required for developers to review and verify results manually. 

• Simple, rapid integration into your existing CI/CD pipeline.

With these types of SAST tooling features, organizations can ensure that their software is developed with security in mind, reducing the risk of vulnerabilities and increasing the overall security of their applications.

Developer-first SAST with Snyk

The ability of SAST tools to catch security problems early in the development process means that even in deadline-driven environments, developers don’t need to constantly worry about following security best practices while coding. However, depending on how late in the software development life cycle you run a SAST, it takes a lot of effort to get it up to speed. 

Conventional SAST tools will yield many false positives, which developers need to weed out. And if the system is coded in a niche programming language, there might not even be a SAST tool available to help with your security issues. Developer-first, modern AI-native SAST tools successfully address these issues and offer a more seamless and efficient process. Developers using such modern tools that detect and fix security issues in real time can also code confidently with AI coding tools, knowing that problems will be caught as they occur without slowing development down. These benefits make progressive SAST tools something every security-conscious developer and organization should have in their toolkit.

Snyk Code is a modern, developer-first SAST that offers real-time scanning that is 50x faster than legacy tools, and auto-fixing that remediates in 12 seconds on average, all within the developer’s own work environment. This speed is complemented by industry-leading accuracy, and a cutting-edge knowledge base that's powered by human-in-the-loop AI. Make application security effortless with AI, and start using Snyk Code for free today.