What Is Static Application Security Testing?
Static application security testing (SAST) analyzes source code, bytecode or binaries without running the application, looking for code patterns and data flows that indicate security vulnerabilities. It runs early in development, often on every pull request.
Also known as:
How SAST Works
A SAST tool parses the code into a model it can reason about, such as a syntax tree and a data-flow graph. It then looks for places where untrusted input, like an HTTP parameter or file upload, can reach a dangerous operation, like a database query, shell command or file path, without being validated. Many tools also check for risky APIs, weak cryptography and hardcoded credentials.
What SAST Is Good At
- Early feedback. Findings appear in the pull request, when the fix is cheapest.
- Full code coverage. It can examine every path, including code that is hard to reach in a running app.
- Precise locations. Results point to the file and line that needs to change.
- Injection-style flaws. SQL injection, command injection, path traversal and similar issues map well to data-flow analysis.
Where SAST Falls Short
- False positives. Without runtime context, tools often flag code that is safe in practice.
- Business logic and authorization. Missing access checks and logic flaws look like normal code to pattern-based rules.
- Configuration and runtime issues. Problems that only appear in a deployed environment are out of view.
- Language and framework coverage. Results depend on how well the tool understands your stack.
SAST vs DAST vs SCA
SAST examines your own code from the inside. DAST tests the running application from the outside. SCA looks at the open source dependencies you pull in. Most programs use all three, because each finds problems the others miss.
How Nullify Approaches SAST
Nullify's AI-native static analysis reasons about how the application actually works instead of matching signatures. It scans every default-branch commit and pull request across 16 languages, traces untrusted input top-down from entry points and bottom-up from dangerous sinks, and validates findings on reachability, exploitability and business context before a human sees them. That lets it catch business logic flaws and IDOR that signature-based SAST misses. See how Nullify Code Security works.
Key Takeaways
- SAST analyzes code without running it to find vulnerable patterns and data flows.
- It gives early, precise feedback in pull requests.
- Its main weaknesses are false positives and missing business logic flaws.
- Use it alongside DAST and SCA, since each covers different risks.
Read More About Static Application Security Testing
Code Security
See Nullify in Action
Nullify reasons about how your app works to find real vulnerabilities, not pattern matches.