Imported from majiayu000/claude-skill-registry-data (data/security-hardening-checklist/SKILL.md). Install upstream with npx skills add majiayu000/claude-skill-registry-data --skill security-hardening-checklist. Copyright stays with the author.

Security Hardening Checklist

To perform a comprehensive security audit and generate hardening recommendations, follow these steps systematically.

Step 1: Project Discovery

Identify the project structure and tech stack:

1. Use Glob to find key files:

   • package.json - Dependencies and scripts
   • next.config.* - Next.js configuration
   • middleware.ts - Middleware setup
   • app/**/*.{ts,tsx} - Application routes
   • .env.example - Environment variables

2. Identify authentication provider (Supabase, NextAuth, Clerk, etc.)

3. Identify database type (PostgreSQL, MySQL, MongoDB, etc.)

4. Check for security libraries (helmet, rate-limit, etc.)

Step 2: Security Headers Audit

Check for security headers configuration.

Check Next.js Config

Use Grep to search for security headers in next.config.js/ts:

- "X-Frame-Options"
- "X-Content-Type-Options"
- "X-XSS-Protection"
- "Strict-Transport-Security"
- "Content-Security-Policy"
- "Referrer-Policy"
- "Permissions-Policy"

Generate Missing Headers

Consult references/security-headers.md and create configuration:

// next.config.ts
const securityHeaders = [
  {
    key: 'X-DNS-Prefetch-Control',
    value: 'on'
  },
  {
    key: 'Strict-Transport-Security',
    value: 'max-age=63072000; includeSubDomains; preload'
  },
  {
    key: 'X-Frame-Options',
    value: 'SAMEORIGIN'
  },
  {
    key: 'X-Content-Type-Options',
    value: 'nosniff'
  },
  {
    key: 'X-XSS-Protection',
    value: '1; mode=block'
  },
  {
    key: 'Referrer-Policy',
    value: 'strict-origin-when-cross-origin'
  },
  {
    key: 'Permissions-Policy',
    value: 'camera=(), microphone=(), geolocation=()'
  }
]

const nextConfig = {
  async headers() {
    return [
      {
        source: '/:path*',
        headers: securityHeaders,
      },
    ]
  },
}

Step 3: Cookie Security Audit

Check cookie configuration for auth and session management.

Check for Insecure Cookie Settings

Use Grep to search for cookie operations:

- "setCookie"
- "cookies().set"
- "document.cookie"
- "res.cookie"

Review Cookie Security Attributes

Check for:

• httpOnly: true - Prevents JavaScript access
• secure: true - HTTPS only
• sameSite: 'strict' or 'lax' - CSRF protection
• Proper expiration times

Generate Secure Cookie Helper

// lib/cookies.ts
import { cookies } from 'next/headers'

export function setSecureCookie(
  name: string,
  value: string,
  maxAge: number = 3600
) {
  cookies().set(name, value, {
    httpOnly: true,
    secure: process.env.NODE_ENV === 'production',
    sameSite: 'strict',
    maxAge,
    path: '/',
  })
}

Step 4: RLS Policy Audit

For Supabase/PostgreSQL projects, audit Row-Level Security.

Check RLS Status

Search for migration files or schema files:

-- Check if RLS is enabled
ALTER TABLE table_name ENABLE ROW LEVEL SECURITY;

Identify Tables Without RLS

Use Grep to find table definitions and check which lack RLS policies.

Flag Security Gaps

• Tables with user data but no RLS
• Tables with RLS but no policies
• Policies that may be too permissive
• Missing WITH CHECK clauses

Consult references/rls-checklist.md for comprehensive checks.

Step 5: Input Sanitization Audit

Check for unsafe input handling.

Search for Direct Database Queries

Use Grep to find potential SQL injection risks:

- "`.query(`"
- "`${" (template literals in queries)
- "raw("

Check Form Input Validation

Search for form handlers without validation:

- "formData.get("
- "request.json()"
- "params."

Validate Zod Usage

Check if forms use Zod or similar validation:

- "z.object"
- "safeParse"
- "parse"

Generate Validation Examples

// lib/validations/common.ts
import { z } from 'zod'

// Sanitize HTML input
export const sanitizeHtml = (input: string): string => {
  return input
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#x27;')
    .replace(/\//g, '&#x2F;')
}

// Common validation schemas
export const emailSchema = z.string().email()
export const urlSchema = z.string().url()
export const uuidSchema = z.string().uuid()
export const slugSchema = z.string().regex(/^[a-z0-9-]+$/)

Step 6: Rate Limiting Audit

Check for rate limiting on API routes and actions.

Check for Rate Limiting Libraries

Search package.json for:

• @upstash/ratelimit
• express-rate-limit
• rate-limiter-flexible

Identify Unprotected Endpoints

Use Glob to find all API routes:

app/api/**/route.ts

Search each for rate limiting code.

Generate Rate Limiting Implementation

// lib/rate-limit.ts
import { Ratelimit } from '@upstash/ratelimit'
import { Redis } from '@upstash/redis'

export const authRateLimit = new Ratelimit({
  redis: Redis.fromEnv(),
  limiter: Ratelimit.slidingWindow(5, '1 m'),
  prefix: 'ratelimit:auth',
})

export const apiRateLimit = new Ratelimit({
  redis: Redis.fromEnv(),
  limiter: Ratelimit.slidingWindow(100, '1 m'),
  prefix: 'ratelimit:api',
})

// Usage in API route
export async function POST(request: Request) {
  const ip = request.headers.get('x-forwarded-for') ?? 'unknown'
  const { success } = await authRateLimit.limit(ip)

  if (!success) {
    return new Response('Rate limit exceeded', { status: 429 })
  }

  // Handle request
}

Step 7: Environment Variables Audit

Check for exposed secrets and proper env var handling.

Check .env.example

Verify sensitive variables are not committed:

• Database URLs with credentials
• API keys
• JWT secrets

Search for Hardcoded Secrets

Use Grep to find potential hardcoded secrets:

- "password.*=.*['\"]"
- "secret.*=.*['\"]"
- "api[-_]?key.*=.*['\"]"
- "token.*=.*['\"]"

Check Client-Side Exposure

Search for env vars used in client components:

- "process.env" in files with "use client"

Only NEXT_PUBLIC_* vars should be in client code.

Step 8: HTTPS and Transport Security

Verify HTTPS is enforced.

Check for HTTP Links

Use Grep to find insecure URLs:

- "http://" (not in comments)

Check Middleware for HTTPS Redirect

Look for HTTPS enforcement in middleware.

Generate HTTPS Enforcement

// middleware.ts
export function middleware(request: NextRequest) {
  // Enforce HTTPS in production
  if (
    process.env.NODE_ENV === 'production' &&
    request.headers.get('x-forwarded-proto') !== 'https'
  ) {
    return NextResponse.redirect(
      `https://${request.headers.get('host')}${request.nextUrl.pathname}`,
      301
    )
  }

  // Other middleware logic
}

Step 9: CORS Configuration Audit

Check CORS configuration for API routes.

Search for CORS Headers

Use Grep to find CORS configuration:

- "Access-Control-Allow-Origin"
- "cors("

Verify CORS is Not Too Permissive

Flag Access-Control-Allow-Origin: * in production.

Generate Proper CORS Configuration

// lib/cors.ts
export function setCorsHeaders(
  response: NextResponse,
  allowedOrigins: string[]
) {
  const origin = request.headers.get('origin')

  if (origin && allowedOrigins.includes(origin)) {
    response.headers.set('Access-Control-Allow-Origin', origin)
    response.headers.set('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE')
    response.headers.set('Access-Control-Allow-Headers', 'Content-Type, Authorization')
    response.headers.set('Access-Control-Max-Age', '86400')
  }

  return response
}

Step 10: Dependency Security Audit

Check for vulnerable dependencies.

Run npm audit

npm audit --json

Check for Outdated Packages

npm outdated

Flag Critical Vulnerabilities

Identify packages with known security issues.

Step 11: Generate Security Report

Create comprehensive security audit report using template from assets/security-report-template.md:

# Security Audit Report

**Generated**: [timestamp]
**Project**: [project name]

## Executive Summary

**Overall Security Score**: X/100

- Critical Issues: X
- High Priority: X
- Medium Priority: X
- Low Priority: X

## Critical Issues (Fix Immediately)

### 1. Missing Security Headers
**Severity**: Critical
**Impact**: Application vulnerable to XSS, clickjacking
**Fix**: Add security headers to next.config.ts

### 2. No Rate Limiting on Auth Endpoints
**Severity**: Critical
**Impact**: Vulnerable to brute force attacks
**Fix**: Implement rate limiting

[Continue for all issues...]

## Recommendations

1. Security Headers
2. Cookie Security
3. RLS Policies
4. Input Validation
5. Rate Limiting
6. HTTPS Enforcement
7. Environment Variables
8. Dependency Updates

## Implementation Checklist

- [ ] Add security headers
- [ ] Configure secure cookies
- [ ] Enable RLS on all tables
- [ ] Add input validation
- [ ] Implement rate limiting
- [ ] Enforce HTTPS
- [ ] Audit environment variables
- [ ] Update vulnerable dependencies

Step 12: Generate Fix Scripts

Create scripts to automate security improvements:

// scripts/add-security-headers.ts
// Automatically adds security headers to next.config

# scripts/enable-rls.sql
# SQL script to enable RLS on all tables

Consulting References

Throughout audit:

• Consult references/security-headers.md for header configuration
• Consult references/rls-checklist.md for database security
• Consult references/owasp-top-10.md for common vulnerabilities
• Use templates from assets/security-report-template.md

Output Format

Generate files:

reports/
  security-audit-[timestamp].md
fixes/
  security-headers.ts
  rate-limiting.ts
  input-validation.ts
scripts/
  enable-rls.sql
  fix-cookies.ts

Verification Checklist

Before completing audit:

• All routes analyzed
• Security headers reviewed
• Cookie configuration checked
• RLS policies audited
• Input validation verified
• Rate limiting assessed
• Environment variables checked
• Dependencies scanned
• HTTPS enforcement verified
• CORS configuration reviewed

Completion

When finished:

1. Display security score
2. Highlight critical issues
3. Provide prioritized recommendations
4. Offer to implement fixes
5. Generate implementation scripts