Stop 10 · Application Security (AppSec)Topics · 7/9

Secure Code Review

In short

Tools catch patterns, but a human spots the subtle logic flaw a scanner misses. Secure code review is reading code with an attacker's mindset before it ships.

Manually reviewing code with a security lens — looking specifically for input validation gaps, authorization checks, and unsafe function usage, complementing automated SAST scanning.

The blob reads over a friend's exam answer sheet and circles a logic gap.

Think of it like this

The second pair of eyes on an exam answer

You reread your own exam answer and it looks fine, because you know what you meant. A friend reads it fresh and instantly spots the gap in your logic. Secure code review is that fresh pair of eyes, hunting for security holes in particular.

Watch it happen

What a reviewer looks for

Input

Authz

Secrets

Unsafe calls

1/4Is every user input validated and used safely, with no unescaped queries or commands?

The big ideas

What you need to know

Think like an attacker

Ask 'how could this input break things?' at each spot where data enters or a decision is made.

Focus on the hotspots

Input handling, authentication, authorisation and anything touching money or secrets deserve the closest look.

Use a checklist

A short, shared checklist keeps reviews consistent and stops the reviewer forgetting a common class of bug.

Humans plus tools

SAST finds patterns fast; a reviewer understands intent and logic. Together they catch far more than either alone.

Save yourself the pain

Common mistakes

Oops

Approving a pull request after a quick skim.

Do this instead

Security review needs focus on risky spots. A rubber stamp lets logic flaws that tools miss slip into production.

Oops

Thinking a passing SAST scan means the code is safe.

Do this instead

Scanners miss logic and authorisation flaws. A human reviewer who understands intent catches what patterns cannot.

Your mission

Review a risky snippet

~35 min

Quick check

Why keep human code review even when SAST tools run automatically?

Go deeper

1Review a sample code snippet specifically for missing input validation or authorization checks.
2Learn to build a personal checklist of common security anti-patterns to watch for during review.
3Practice explaining a security finding to a developer constructively, not just flagging it.