semgrep-rule-creator

To write a Semgrep rule for detecting security vulnerabilities, you define a YAML configuration specifying the target pattern and use taint mode to track untrusted input reaching dangerous sinks, validating the rule with deterministic test cases.

Taint mode in static analysis tracks data flow from untrusted sources to dangerous sinks, reducing false positives. You should use taint mode for secure coding when detecting vulnerabilities involving user input reaching sensitive functions.

You test Semgrep rules by creating a test file with vulnerable, safe, and edge-case code variations, then running semgrep --test to verify 100% pass rate before considering the rule complete and validated against false positives.

You can use Semgrep pattern matching to enforce custom coding standards by creating YAML rules that detect buggy code patterns, applying guardrails against overly broad configurations to ensure high precision and accurate detection.

Semgrep static analysis rules produce false positives on safe code when they lack precise pattern definitions or proper test coverage, requiring taint mode for data-flow vulnerabilities and mandatory semgrep --test verification to resolve.

The best way to create custom static analysis rules for unvalidated input is authoring taint-mode Semgrep YAML configurations with mandatory documentation review and deterministic test validation covering vulnerable and safe code variations.