security-review

name	Security Review
description	Review a change for what it lets an attacker do, and file what it finds on the security-findings ledger.
category	Engineering

Security Review

Not a checklist pass. The question is what somebody could do that they should not be able to do, and the answer is usually about identity and boundaries rather than about the code being reviewed.

When to use

• Auth, sessions, permissions, payments, file upload, or anything that keeps one customer's data away from another's.
• A dependency with a published advisory.
• Anything that takes input from outside and does something consequential with it.

Steps

1. Name the trust boundary the change crosses. Data moving from untrusted to trusted is where nearly everything lives.
2. Ask who the caller is, and how you know. Authentication answers who; authorization answers whether they may. A change that only checks the first is the most common real finding.
3. Follow the identifier. Anything a client supplies that names a record — an id, a path, a filename, a tenant slug — is an access-control question until proved otherwise.
4. Check the failure path. Errors that leak, retries that duplicate a charge, timeouts that fall open rather than closed.
5. File what you find. record_entry on security-findings with the severity judged on what it lets somebody do, not on how hard it was to spot, and the exploitability stating what an attacker needs first.
6. Close with reasoning. not_exploitable is a legitimate close and it must carry the argument. Silence here is what makes the same finding cost the company twice.