Api security hardening

Skill secondsky/claude-skills/plugins/api-security-hardening/skills/api-security-hardening

Production-ready skills for Claude Code CLI - Cloudflare, React, Tailwind v4, and AI integrations

Install

npx -y skills add secondsky/claude-skills --skill api-security-hardening

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What its author says it does

Copied from the file, not written here

REST API security hardening with authentication, rate limiting, input validation, security headers. Use for production APIs, security audits, defense-in-depth, or encountering vulnerabilities, injection attacks, CORS issues.

The file declares its own license as MIT. That is the author’s claim about this one file, and it is not the same thing as the license GitHub reports for the repository, which is listed with the other numbers below.

SKILL.md

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API Security Hardening

Protect REST APIs against common vulnerabilities with multiple security layers.

Security Middleware Stack (Express)

const helmet = require('helmet');
const rateLimit = require('express-rate-limit');
const mongoSanitize = require('express-mongo-sanitize');

app.use(helmet());
app.use(mongoSanitize());
// For input sanitization, see the `xss-prevention` skill — do NOT use the
// deprecated `xss-clean` package (unmaintained since 2018; its own README
// recommends migrating off it).

app.use('/api/', rateLimit({
  windowMs: 15 * 60 * 1000,
  max: 100
}));

app.use('/api/auth/', rateLimit({
  windowMs: 15 * 60 * 1000,
  max: 5
}));

Input Validation

const { body, validationResult } = require('express-validator');
const escapeHtml = require('escape-html');

app.post('/users',
  body('email').isEmail().normalizeEmail(),
  body('password').isLength({ min: 8 }).matches(/[A-Z]/).matches(/[0-9]/),
  // express-validator v7+ removed the built-in .escape() sanitizer; use a
  // customSanitizer backed by `escape-html` to HTML-escape the value.
  body('name').trim().isLength({ max: 100 }).customSanitizer(v => escapeHtml(v)),
  (req, res) => {
    const errors = validationResult(req);
    if (!errors.isEmpty()) {
      return res.status(400).json({ errors: errors.array() });
    }
    // Process request
  }
);

Security Headers

app.use((req, res, next) => {
  res.setHeader('Content-Security-Policy', "default-src 'self'");
  res.setHeader('X-Frame-Options', 'DENY');
  res.setHeader('X-Content-Type-Options', 'nosniff');
  res.setHeader('Strict-Transport-Security', 'max-age=31536000; includeSubDomains');
  res.setHeader('X-XSS-Protection', '1; mode=block');
  next();
});

Security Checklist

HTTPS everywhere
Authentication on all protected routes
Input validation and sanitization
Rate limiting enabled
Security headers configured
CORS restricted to allowed origins
No stack traces in production errors
Audit logging enabled
Dependencies regularly updated

Additional Implementations

See references/python-nginx.md for:

Python FastAPI security middleware
Pydantic input validation with password rules
Nginx SSL/TLS and security headers configuration
HTTP Parameter Pollution prevention

Never Do

Trust user input without validation
Return detailed errors in production
Store secrets in code
Use GET for state-changing operations
Disable security for convenience