security

security is a skill for Claude Code, Codex from gc-victor/supersimple. It costs 45 tokens per session (563 once invoked), scanned A, original, MIT.

A security checklist and workflow for code that handles user input, logins, stored data, or connections to outside services.

In plain words
What is it for?
Use it when building or changing authentication, data storage, external integrations, file uploads, permissions, or other features that accept untrusted data.
Why use it?
It reduces common risks such as unauthorized access, injection attacks, exposed secrets, unsafe uploads, and insecure browser settings.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it when building or changing authentication, data storage, external integrations, file uploads, permissions, or other features that accept untrusted data.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/gc-victor/supersimple/security
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.

Any agent
npx skills add gc-victor/supersimple --skill security
Clone the repo
git clone --depth 1 https://github.com/gc-victor/supersimple

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for security

README.md
[![agentmods](https://agentmods.dev/badge/skills/gc-victor/supersimple/security.svg)](https://agentmods.dev/skills/gc-victor/supersimple/security)
Your own site
<a href="https://agentmods.dev/skills/gc-victor/supersimple/security"><img src="https://agentmods.dev/badge/skills/gc-victor/supersimple/security.svg" alt="Measured on agentmods" height="20"></a>
Per session 45 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 563 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found 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 5.1 $0.00045 $0.00563
Opus 5 $0.00023 $0.00282
Sonnet 5 $0.00009 $0.00113
Haiku 4.5 $0.00005 $0.00056

Measured 8d ago against content hash cb39ff0f10f1, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

security 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 8d 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.

skills/security/SKILL.md · 72 lines

How it starts

The opening of the file, as written. The whole thing — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Security and Hardening

Treat every external input as hostile, every secret as sacred, and every authorization check as mandatory. This skill MUST apply security constraints to every line of code that touches user data, authentication, or external systems.

What to Do

  • Validate all external input at system boundaries.
  • Parameterize all database queries.
  • Encode output to prevent XSS; use framework auto-escaping.
  • Hash passwords with bcrypt/scrypt/argon2 (salt rounds ≥ 12).
  • Use httpOnly, secure, sameSite cookies for sessions.
  • Check authorization on every protected endpoint.
  • Set security headers (CSP, HSTS, X-Frame-Options, X-Content-Type-Options).
  • Use HTTPS for all external communication.
  • Run dependency audits before release.
  • Restrict CORS to known origins.
  • Sanitize file uploads by type and size; do not trust extensions.

Ask First

  • Adding or changing authentication flows.
  • Storing new categories of sensitive data.
  • Adding external service integrations.
  • Changing CORS configuration.
  • Adding file upload handlers.
  • Modifying rate limiting.
  • Granting elevated permissions.

Never Do

  • Commit secrets to version control.
  • Log sensitive data.
  • Trust client-side validation as a security boundary.
  • Disable security headers for convenience.
  • Use eval() or innerHTML with user-provided data.
  • Store sessions in client-accessible storage.
  • Expose stack traces or internal errors to users.

Process

  1. Identify the attack surface (input points, auth, data flow).
  2. Verify input validation exists at boundaries.
  3. Check authorization on every affected endpoint.
  4. Confirm secrets are not hardcoded or logged.
  5. Verify security headers and transport security.
  6. Run npm audit (or equivalent) and triage findings.

Verification

  • No critical or high vulnerabilities in dependencies.
  • No secrets in source code or git history.
  • All user input validated at system boundaries.
  • Authentication and authorization checked on every protected endpoint.
  • Security headers present in responses.
  • Error responses do not expose internal details.
  • Rate limiting active on authentication endpoints.

Read the full file on GitHub · 72 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. 8d ago First seen · 72 lines · 45 tokens per session scan A cb39ff0f10f1

Subscribe to this mod's changes

security is a skill published in the GitHub repository gc-victor/supersimple (33 stars, last pushed 4mo ago), licensed MIT. It adds 45 tokens to every session and 563 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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