security

security is a skill for Claude Code, Codex from krzysztofsurdy/code-virtuoso. It costs 89 tokens per session (3,025 once invoked), scanned A, original, MIT.

A guide to common web-application security risks, based on the OWASP Top 10, a widely used list of serious web security problems. It covers user access, sensitive data, secrets, input handling, and security settings.

In plain words
What is it for?
Use it when designing or reviewing features, implementing login and permissions, handling secrets or sensitive data, configuring security headers, or responding to a vulnerability.
Why use it?
It helps find and prevent problems such as SQL injection, cross-site scripting, forged requests, stolen credentials, and exposed API keys.

Skill for Claude CodeCodex

Part of the knowledge-virtuoso plugin — 15 skills shipped together

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/krzysztofsurdy/code-virtuoso/security
Any agent
npx skills add krzysztofsurdy/code-virtuoso --skill security
Clone the repo
git clone --depth 1 https://github.com/krzysztofsurdy/code-virtuoso

Made for: Claude Code, Codex.

Or install knowledge-virtuoso, the plugin that ships this one along with the rest of its 15 skills.

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/krzysztofsurdy/code-virtuoso/security.svg)](https://agentmods.dev/skills/krzysztofsurdy/code-virtuoso/security)
Your own site
<a href="https://agentmods.dev/skills/krzysztofsurdy/code-virtuoso/security"><img src="https://agentmods.dev/badge/skills/krzysztofsurdy/code-virtuoso/security.svg" alt="Measured on agentmods" height="20"></a>
Per session 89 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,025 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00089 $0.03025
Opus 5 $0.00044 $0.01512
Sonnet 5 $0.00018 $0.00605
Haiku 4.5 $0.00009 $0.00302

Measured 5d ago against content hash 0e34ac692e64, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, 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 5d 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/knowledge/security/SKILL.md · 267 lines

How it starts

The opening of the file, as written. The whole thing — 267 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Security

Security is not a feature — it is a property of every feature. Every endpoint, every form, every data flow, every integration point must be designed with security in mind from the start. Bolting security on after the fact is expensive, error-prone, and often incomplete.

This skill provides stack-agnostic guidance for building secure applications. It covers the OWASP Top 10, input validation, authentication and authorization patterns, data protection, secrets management, security headers, and common antipatterns.

When to Use

Consult this skill when:

  • Designing a new feature that handles user input, authentication, or sensitive data
  • Reviewing code for security concerns
  • Implementing authentication or authorization flows
  • Handling secrets, API keys, or credentials
  • Configuring HTTP security headers
  • Assessing whether a dependency or design choice introduces risk
  • Preparing for a security audit or penetration test
  • Responding to a security incident or vulnerability report

OWASP Top 10

The OWASP Top 10 (2021 edition) represents the most critical security risks to web applications. Use this as a starting checklist — not an exhaustive list.

# Vulnerability What It Is Primary Defense
A01 Broken Access Control Users act outside intended permissions Deny by default, enforce server-side
A02 Cryptographic Failures Sensitive data exposed due to weak/missing crypto Use strong algorithms, encrypt in transit and at rest
A03 Injection Untrusted data sent to interpreter as part of a command/query Parameterized queries, input validation
A04 Insecure Design Missing or ineffective security controls by design Threat modeling, secure design patterns
A05 Security Misconfiguration Insecure default configs, incomplete setup Hardened defaults, automated config validation
A06 Vulnerable Components Using components with known vulnerabilities Dependency scanning, timely updates
A07 Auth Failures Broken authentication/identification MFA, rate limiting, secure password storage
A08 Integrity Failures Code/data integrity not verified Signed updates, CI/CD integrity checks
A09 Logging Failures Insufficient logging and monitoring Log security events, set up alerting
A10 SSRF Server tricked into making unintended requests Allowlist destinations, sanitize URLs

Read the full file on GitHub · 267 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 5d ago First seen · 267 lines · 89 tokens per session scan A 0e34ac692e64

Subscribe to this mod's changes

security is a skill published in the GitHub repository krzysztofsurdy/code-virtuoso (20 stars, last pushed 3mo ago), licensed MIT. It adds 89 tokens to every session and 3,025 once invoked, about $0.0004 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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