security-and-hardening

A security review guide for web applications that examines threats, attack paths, and ways to make code safer.

In plain words
What is it for?
Use it when building features such as login, permissions, file uploads, webhooks, payments, or handling personal data.
Why use it?
It helps find weaknesses involving user input, accounts, secrets, databases, and outside services before they can be exploited.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/whitequeen306/code-cortex-loop/security-review
Any agent
npx skills add whitequeen306/code-cortex-loop --skill security-review
Clone the repo
git clone --depth 1 https://github.com/whitequeen306/code-cortex-loop

Made for: Claude Code, Codex.

Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,718 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 91% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00040 $0.02718
Opus 5 $0.00020 $0.01359
Sonnet 5 $0.00008 $0.00544
Haiku 4.5 $0.00004 $0.00272

Measured 2d ago against content hash 6e6069b43a10, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

security-and-hardening scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

91% identical to security-and-hardening — 6 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/security-review/SKILL.md · 352 lines

How it starts

The opening of the file, as written. The whole thing — 352 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Security and Hardening

Depth skill for pass 2 (security) only. Pair with cortexloop-expert-core. Rule: security-hardening.

Go deep on security. The OWASP sections below are your depth material — trace exploit paths, don't skim checklists. Logic bugs without exploit → defer review.

Security-first development practices for web applications. Treat every external input as hostile, every secret as sacred, and every authorization check as mandatory. Security isn't a phase — it's a constraint on every line of code that touches user data, authentication, or external systems.

When to Use

  • Building anything that accepts user input
  • Implementing authentication or authorization
  • Storing or transmitting sensitive data
  • Integrating with external APIs or services
  • Adding file uploads, webhooks, or callbacks
  • Handling payment or PII data

The Three-Tier Boundary System

Always Do (No Exceptions)

  • Validate all external input at the system boundary (API routes, form handlers)
  • Parameterize all database queries — never concatenate user input into SQL
  • Encode output to prevent XSS (use framework auto-escaping, don't bypass it)
  • Use HTTPS for all external communication
  • Hash passwords with bcrypt/scrypt/argon2 (never store plaintext)
  • Set security headers (CSP, HSTS, X-Frame-Options, X-Content-Type-Options)
  • Use httpOnly, secure, sameSite cookies for sessions
  • Run npm audit (or equivalent) before every release

Ask First (Requires Human Approval)

  • Adding new authentication flows or changing auth logic
  • Storing new categories of sensitive data (PII, payment info)
  • Adding new external service integrations
  • Changing CORS configuration
  • Adding file upload handlers
  • Modifying rate limiting or throttling
  • Granting elevated permissions or roles

Never Do

  • Never commit secrets to version control (API keys, passwords, tokens)
  • Never log sensitive data (passwords, tokens, full credit card numbers)
  • Never trust client-side validation as a security boundary
  • Never disable security headers for convenience
  • Never use eval() or innerHTML with user-provided data
  • Never store sessions in client-accessible storage (localStorage for auth tokens)
  • Never expose stack traces or internal error details to users

Read the full file on GitHub · 352 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 352 lines · 40 tokens per session scan A 6e6069b43a10

Subscribe to this mod's changes

security-and-hardening is a skill published in the GitHub repository whitequeen306/code-cortex-loop (15 stars, last pushed 1mo ago), licensed MIT. It adds 40 tokens to every session and 2,718 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 91% identical to security-and-hardening, differing in 6 lines, and is treated as a copy.

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