Source Code Security
Secure Code Review vs Automated SAST Tools: What Actually Catches Bugs
Why static analysis tools and manual code review find different classes of vulnerabilities.
LOZULA Senior Security Research Team
2025-12-09
7 min read
Key Takeaways for Security Teams
- SAST tools are a useful first pass, not a substitute for review by a security engineer.
- Most SAST tools produce a high false-positive rate that still needs human triage.
- The highest-severity findings in real audits are usually logic flaws, not pattern-matchable syntax issues.
Automated SAST tools are fast and good at catching known patterns, but manual secure code review is what finds business logic flaws, authorization gaps, and context-dependent bugs that pattern matching cannot see.
What SAST Tools Are Good At
Static Application Security Testing tools scan source code without executing it, matching known-bad patterns at scale.
- •Fast, repeatable scans across large codebases on every commit
- •Strong at catching known CWE patterns: SQL injection sinks, hardcoded credentials, insecure deserialization
- •Cheap to run continuously in CI/CD pipelines
What Manual Review Catches That Tools Miss
The vulnerabilities that actually lead to breaches are frequently the ones that require understanding what the code is supposed to do, not just what it does.
- •Authorization logic errors, where a check exists but applies the wrong condition
- •Multi-step business logic flaws spanning several files and functions
- •Race conditions and time-of-check-to-time-of-use (TOCTOU) bugs
- •Cryptographic misuse that is syntactically valid but semantically broken