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.
npx skills add juanmhidalgo/claude-plugins --skill security-hardeninggit clone --depth 1 https://github.com/juanmhidalgo/claude-pluginsWrote 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.
[](https://agentmods.dev/skills/juanmhidalgo/claude-plugins/security-hardening)<a href="https://agentmods.dev/skills/juanmhidalgo/claude-plugins/security-hardening"><img src="https://agentmods.dev/badge/skills/juanmhidalgo/claude-plugins/security-hardening/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/juanmhidalgo/claude-plugins/security-hardening"><img src="https://agentmods.dev/badge/skills/juanmhidalgo/claude-plugins/security-hardening.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00041 | $0.01234 |
| Opus 5 | $0.00020 | $0.00617 |
| Sonnet 5 | $0.00008 | $0.00247 |
| Haiku 4.5 | $0.00004 | $0.00123 |
Grade A, and why
security-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 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.
How it starts
The opening of the file, as written. The whole thing — 143 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Security and Hardening
Security is a constraint on every line of code that touches user data, authentication, or external systems. Treat every external input as hostile, every secret as sacred, and every authorization check as mandatory.
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)
- Hash passwords with bcrypt/scrypt/argon2 (salt rounds ≥ 12)
- Set security headers (CSP, HSTS, X-Frame-Options, X-Content-Type-Options)
- Use httpOnly, secure, sameSite cookies for sessions
- Audit dependencies before every release (
npm audit/pip audit) - Use HTTPS for all external communication
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()orinnerHTMLwith user-provided data - Never store auth tokens in localStorage (use httpOnly cookies)
- Never expose stack traces or internal error details to users
OWASP Top 10 Quick Reference
| # | Vulnerability | Prevention |
|---|---|---|
| 1 | Injection | Parameterized queries, ORM, no string concatenation |
| 2 | Broken Auth | Strong hashing, secure sessions, rate limiting |
| 3 | XSS | Framework auto-escaping, DOMPurify for raw HTML |
| 4 | Broken Access Control | Ownership checks on every endpoint, IDOR prevention |
| 5 | Misconfiguration | Helmet/security headers, restrictive CORS, no defaults |
| 6 | Sensitive Data Exposure | Sanitize responses, env vars for secrets, encrypt PII |
What ships with it
2 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.
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.
- 5d ago First seen · 143 lines · 41 tokens per session scan A b666328c98a3
security-hardening is a skill published in the GitHub repository juanmhidalgo/claude-plugins (8 stars, last pushed today), licensed MIT. It adds 41 tokens to every session and 1,234 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 2026-09-03.
Other skills, from other repositories
API Security Testing
Comprehensive API security testing based on OWASP API Security Top 10 including broken authentication, injection attacks, rate limiting, BOLA/BFLA vulnerabilities, and automated security scanning with ZAP and custom scripts.
security-practices
OWASP Top 10, authentication, and secure coding practices.
Web Application Security Testing
OWASP Top 10 testing, injection vulnerability detection, API security assessment, authentication testing, and web vulnerability reporting for authorized assessments.
security-patterns
Security patterns for authentication, defense-in-depth, input validation, OWASP Top 10, LLM safety, and PII masking. Use when implementing auth flows, security layers, input sanitization, vulnerability prevention, prompt injection defense, or data redaction.
security-practices
Security practices for enterprise applications. Spring Security, parameterized queries, input validation, secret management, OWASP Top 10.
security-audit
Audit code and infrastructure for security vulnerabilities. Use when performing security reviews, checking for OWASP Top 10 issues, auditing dependencies, or hardening applications.