How Static Application Security Testing Works

SAST tools employ sophisticated analysis techniques to understand code behavior without executing it. The analysis process begins with parsing source code into abstract syntax trees (ASTs) that represent code structure in a form amenable to analysis. These ASTs enable tools to understand relationships between different code components, trace variable usage, and model program behavior.

Data flow analysis tracks how information moves through applications, identifying paths where untrusted input might reach sensitive operations. For example, SAST tools can trace user input from web forms through multiple function calls to database queries, identifying potential SQL injection vulnerabilities. This analysis considers all possible execution paths, including error conditions and edge cases that might be missed during testing.

Control flow analysis examines program execution paths to identify security-relevant patterns. Tools can detect missing authentication checks, improper error handling, and race conditions by analyzing how programs make decisions and handle different scenarios. Taint analysis combines data and control flow analysis to track potentially malicious input through applications, identifying where sanitization or validation might be missing.