AppSec code review practice for juniors

Start with trust boundaries

Junior reviewers often scan for keywords instead of following data. Begin with where untrusted input enters the application and where privileged actions happen.

Ask: can an attacker influence this value, and does the code treat it as trusted later?

Name the weakness without overclaiming

Good review comments are specific: the sink, the missing control, and the realistic impact. Avoid declaring remote code execution when the evidence only supports injection into a constrained query or response.

Practice on synthetic handlers

Safe practice should use simulated services and intentionally flawed snippets, not production customer code or live exploit chains. Short missions that highlight one risky pattern help you build pattern recognition without unsafe side quests.