Static Application Security Testing (SAST) analyzes source code to find security vulnerabilities before your application runs. Learn how it works and when to use it.
SAST (Static Application Security Testing) is a white-box testing method that examines application source code, bytecode, or binary code to identify security vulnerabilities. Unlike dynamic testing, SAST doesn't require the application to be running.
A code reviewer that reads every line of your code looking for security issues. It's like having a security expert review your code 24/7, catching vulnerabilities before they reach production.
The SAST tool parses your source code into an Abstract Syntax Tree (AST) or intermediate representation, understanding the code structure.
Traces how data flows through your application, from sources (user input) to sinks (database queries, HTML output) to find tainted data paths.
Compares code against known vulnerability patterns (e.g., SQL injection, XSS) using rules and signatures.
Produces detailed reports with vulnerability locations, severity ratings, and remediation guidance.
Unsanitized user input in database queries
Unescaped user input in HTML output
API keys, passwords in source code
Unvalidated file paths from user input
User input in shell commands
Deserializing untrusted data
Weak algorithms, improper key handling
Missing auth checks, weak sessions
| Aspect | SAST | DAST |
|---|---|---|
| Testing Type | White-box (source code) | Black-box (running app) |
| When Used | During development | After deployment |
| Requires | Source code access | Running application URL |
| Finds | Code-level vulnerabilities | Runtime vulnerabilities |
| False Positives | More common | Less common |
| Code Location | Exact line number | URL/endpoint only |
Best Practice: Use both SAST and DAST together. SAST catches issues early in development; DAST verifies the deployed application is secure.
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Ideally, on every commit via CI/CD pipeline. At minimum, run scans before each release. More frequent scanning catches issues earlier when they're cheaper to fix.
Yes. Human reviewers miss things, especially subtle security issues. SAST catches patterns humans overlook and scales to large codebases. Use both together.
Configure rules to match your codebase, suppress known false positives, and choose tools with good precision. Some false positives are inevitable—factor in triage time.
Yes. SAST is especially valuable for AI-generated code since AI models can produce vulnerable patterns. Scan all code regardless of origin.
Find vulnerabilities in your application before they reach production.
Scan Your App FreeLast updated: January 2025