security-review

•

24.4k23903 months ago

Use this skill when adding authentication, handling user input, working with secrets, creating API endpoints, or implementing payment/sensitive features. Provides comprehensive security checklist and patterns.

Quick Install

npxskills add davila7/claude-code-templates--skill security-review

Instructions

Security Review Skill

This skill ensures all code follows security best practices and identifies potential vulnerabilities.

When to Activate

Implementing authentication or authorization
Handling user input or file uploads
Creating new API endpoints
Working with secrets or credentials
Implementing payment features
Storing or transmitting sensitive data
Integrating third-party APIs

Security Checklist

1. Secrets Management

❌ NEVER Do This

const apiKey = "sk-proj-xxxxx"  // Hardcoded secret
const dbPassword = "password123" // In source code

✅ ALWAYS Do This

const apiKey = process.env.OPENAI_API_KEY
const dbUrl = process.env.DATABASE_URL

// Verify secrets exist
if (!apiKey) {
  throw new Error('OPENAI_API_KEY not configured')
}

Verification Steps

No hardcoded API keys, tokens, or passwords
All secrets in environment variables
.env.local in .gitignore
No secrets in git history
Production secrets in hosting platform (Vercel, Railway)

2. Input Validation

Always Validate User Input

import { z } from 'zod'

// Define validation schema
const CreateUserSchema = z.object({
  email: z.string().email(),
  name: z.string().min(1).max(100),
  age: z.number().int().min(0).max(150)
})

// Validate before processing
export async function createUser(input: unknown) {
  try {
    const validated = CreateUserSchema.parse(input)
    return await db.users.create(validated)
  } catch (error) {
    if (error instanceof z.ZodError) {
      return { success: false, errors: error.errors }
    }
    throw error
  }
}

File Upload Validation

function validateFileUpload(file: File) {
  // Size check (5MB max)
  const maxSize = 5 * 1024 * 1024
  if (file.size > maxSize) {
    throw new Error('File too large (max 5MB)')
  }

  // Type check
  const allowedTypes = ['image/jpeg', 'image/png', 'image/gif']
  if (!allowedTypes.includes(file.type)) {
    throw new Error('Invalid file type')
  }

  // Extension check
  const allowedExtensions = ['.jpg', '.jpeg', '.png', '.gif']
  const extension = file.name.toLowerCase().match(/\.[^.]+$/)?.[0]
  if (!extension || !allowedExtensions.includes(extension)) {
    throw new Error('Invalid file extension')
  }

  return true
}

Verification Steps

All user inputs validated with schemas
File uploads restricted (size, type, extension)
No direct use of user input in queries
Whitelist validation (not blacklist)
Error messages don't leak sensitive info

3. SQL Injection Prevention

❌ NEVER Concatenate SQL

// DANGEROUS - SQL Injection vulnerability
const query = `SELECT * FROM users WHERE email = '${userEmail}'`
await db.query(query)

✅ ALWAYS Use Parameterized Queries

// Safe - parameterized query
const { data } = await supabase
  .from('users')
  .select('*')
  .eq('email', userEmail)

// Or with raw SQL
await db.query(
  'SELECT * FROM users WHERE email = $1',
  [userEmail]
)

Verification Steps

All database queries use parameterized queries
No string concatenation in SQL
ORM/query builder used correctly
Supabase queries properly sanitized

4. Authentication & Authorization

JWT Token Handling

// ❌ WRONG: localStorage (vulnerable to XSS)
localStorage.setItem('token', token)

// ✅ CORRECT: httpOnly cookies
res.setHeader('Set-Cookie',
  `token=${token}; HttpOnly; Secure; SameSite=Strict; Max-Age=3600`)

Authorization Checks

export async function deleteUser(userId: string, requesterId: string) {
  // ALWAYS verify authorization first
  const requester = await db.users.findUnique({
    where: { id: requesterId }
  })

  if (requester.role !== 'admin') {
    return NextResponse.json(
      { error: 'Unauthorized' },
      { status: 403 }
    )
  }

  // Proceed with deletion
  await db.users.delete({ where: { id: userId } })
}

Row Level Security (Supabase)

-- Enable RLS on all tables
ALTER TABLE users ENABLE ROW LEVEL SECURITY;

-- Users can only view their own data
CREATE POLICY "Users view own data"
  ON users FOR SELECT
  USING (auth.uid() = id);

-- Users can only update their own data
CREATE POLICY "Users update own data"
  ON users FOR UPDATE
  USING (auth.uid() = id);

Verification Steps

Tokens stored in httpOnly cookies (not localStorage)
Authorization checks before sensitive operations
Row Level Security enabled in Supabase
Role-based access control implemented
Session management secure

5. XSS Prevention

Sanitize HTML

import DOMPurify from 'isomorphic-dompurify'

// ALWAYS sanitize user-provided HTML
function renderUserContent(html: string) {
  const clean = DOMPurify.sanitize(html, {
    ALLOWED_TAGS: ['b', 'i', 'em', 'strong', 'p'],
    ALLOWED_ATTR: []
  })
  return <div dangerouslySetInnerHTML={{ __html: clean }} />
}

Content Security Policy

// next.config.js
const securityHeaders = [
  {
    key: 'Content-Security-Policy',
    value: `
      default-src 'self';
      script-src 'self' 'unsafe-eval' 'unsafe-inline';
      style-src 'self' 'unsafe-inline';
      img-src 'self' data: https:;
      font-src 'self';
      connect-src 'self' https://api.example.com;
    `.replace(/\s{2,}/g, ' ').trim()
  }
]

Verification Steps

User-provided HTML sanitized
CSP headers configured
No unvalidated dynamic content rendering
React's built-in XSS protection used

6. CSRF Protection

CSRF Tokens

import { csrf } from '@/lib/csrf'

export async function POST(request: Request) {
  const token = request.headers.get('X-CSRF-Token')

  if (!csrf.verify(token)) {
    return NextResponse.json(
      { error: 'Invalid CSRF token' },
      { status: 403 }
    )
  }

  // Process request
}

SameSite Cookies

res.setHeader('Set-Cookie',
  `session=${sessionId}; HttpOnly; Secure; SameSite=Strict`)

Verification Steps

CSRF tokens on state-changing operations
SameSite=Strict on all cookies
Double-submit cookie pattern implemented

7. Rate Limiting

API Rate Limiting

import rateLimit from 'express-rate-limit'

const limiter = rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 100, // 100 requests per window
  message: 'Too many requests'
})

// Apply to routes
app.use('/api/', limiter)

Expensive Operations

// Aggressive rate limiting for searches
const searchLimiter = rateLimit({
  windowMs: 60 * 1000, // 1 minute
  max: 10, // 10 requests per minute
  message: 'Too many search requests'
})

app.use('/api/search', searchLimiter)

Verification Steps

Rate limiting on all API endpoints
Stricter limits on expensive operations
IP-based rate limiting
User-based rate limiting (authenticated)

8. Sensitive Data Exposure

Logging

// ❌ WRONG: Logging sensitive data
console.log('User login:', { email, password })
console.log('Payment:', { cardNumber, cvv })

// ✅ CORRECT: Redact sensitive data
console.log('User login:', { email, userId })
console.log('Payment:', { last4: card.last4, userId })

Error Messages

// ❌ WRONG: Exposing internal details
catch (error) {
  return NextResponse.json(
    { error: error.message, stack: error.stack },
    { status: 500 }
  )
}

// ✅ CORRECT: Generic error messages
catch (error) {
  console.error('Internal error:', error)
  return NextResponse.json(
    { error: 'An error occurred. Please try again.' },
    { status: 500 }
  )
}

Verification Steps

No passwords, tokens, or secrets in logs
Error messages generic for users
Detailed errors only in server logs
No stack traces exposed to users

9. Blockchain Security (Solana)

Wallet Verification

import { verify } from '@solana/web3.js'

async function verifyWalletOwnership(
  publicKey: string,
  signature: string,
  message: string
) {
  try {
    const isValid = verify(
      Buffer.from(message),
      Buffer.from(signature, 'base64'),
      Buffer.from(publicKey, 'base64')
    )
    return isValid
  } catch (error) {
    return false
  }
}

Transaction Verification

async function verifyTransaction(transaction: Transaction) {
  // Verify recipient
  if (transaction.to !== expectedRecipient) {
    throw new Error('Invalid recipient')
  }

  // Verify amount
  if (transaction.amount > maxAmount) {
    throw new Error('Amount exceeds limit')
  }

  // Verify user has sufficient balance
  const balance = await getBalance(transaction.from)
  if (balance < transaction.amount) {
    throw new Error('Insufficient balance')
  }

  return true
}

Verification Steps

Wallet signatures verified
Transaction details validated
Balance checks before transactions
No blind transaction signing

10. Dependency Security

Regular Updates

# Check for vulnerabilities
npm audit

# Fix automatically fixable issues
npm audit fix

# Update dependencies
npm update

# Check for outdated packages
npm outdated

Lock Files

# ALWAYS commit lock files
git add package-lock.json

# Use in CI/CD for reproducible builds
npm ci  # Instead of npm install

Verification Steps

Dependencies up to date
No known vulnerabilities (npm audit clean)
Lock files committed
Dependabot enabled on GitHub
Regular security updates

Security Testing

Automated Security Tests

// Test authentication
test('requires authentication', async () => {
  const response = await fetch('/api/protected')
  expect(response.status).toBe(401)
})

// Test authorization
test('requires admin role', async () => {
  const response = await fetch('/api/admin', {
    headers: { Authorization: `Bearer ${userToken}` }
  })
  expect(response.status).toBe(403)
})

// Test input validation
test('rejects invalid input', async () => {
  const response = await fetch('/api/users', {
    method: 'POST',
    body: JSON.stringify({ email: 'not-an-email' })
  })
  expect(response.status).toBe(400)
})

// Test rate limiting
test('enforces rate limits', async () => {
  const requests = Array(101).fill(null).map(() =>
    fetch('/api/endpoint')
  )

  const responses = await Promise.all(requests)
  const tooManyRequests = responses.filter(r => r.status === 429)

  expect(tooManyRequests.length).toBeGreaterThan(0)
})

Pre-Deployment Security Checklist

Before ANY production deployment:

Secrets: No hardcoded secrets, all in env vars
Input Validation: All user inputs validated
SQL Injection: All queries parameterized
XSS: User content sanitized
CSRF: Protection enabled
Authentication: Proper token handling
Authorization: Role checks in place
Rate Limiting: Enabled on all endpoints
HTTPS: Enforced in production
Security Headers: CSP, X-Frame-Options configured
Error Handling: No sensitive data in errors
Logging: No sensitive data logged
Dependencies: Up to date, no vulnerabilities
Row Level Security: Enabled in Supabase
CORS: Properly configured
File Uploads: Validated (size, type)
Wallet Signatures: Verified (if blockchain)

Resources

Remember: Security is not optional. One vulnerability can compromise the entire platform. When in doubt, err on the side of caution.

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Tags & Topics

anthropicanthropic-claudeclaudeclaude-code

Security Review Skill

This skill ensures all code follows security best practices and identifies potential vulnerabilities.

When to Activate

Implementing authentication or authorization
Handling user input or file uploads
Creating new API endpoints
Working with secrets or credentials
Implementing payment features
Storing or transmitting sensitive data
Integrating third-party APIs

Security Checklist

1. Secrets Management

❌ NEVER Do This

const apiKey = "sk-proj-xxxxx"  // Hardcoded secret
const dbPassword = "password123" // In source code

✅ ALWAYS Do This

const apiKey = process.env.OPENAI_API_KEY
const dbUrl = process.env.DATABASE_URL

// Verify secrets exist
if (!apiKey) {
  throw new Error('OPENAI_API_KEY not configured')
}

Verification Steps

No hardcoded API keys, tokens, or passwords
All secrets in environment variables
.env.local in .gitignore
No secrets in git history
Production secrets in hosting platform (Vercel, Railway)

2. Input Validation

Always Validate User Input

import { z } from 'zod'

// Define validation schema
const CreateUserSchema = z.object({
  email: z.string().email(),
  name: z.string().min(1).max(100),
  age: z.number().int().min(0).max(150)
})

// Validate before processing
export async function createUser(input: unknown) {
  try {
    const validated = CreateUserSchema.parse(input)
    return await db.users.create(validated)
  } catch (error) {
    if (error instanceof z.ZodError) {
      return { success: false, errors: error.errors }
    }
    throw error
  }
}

File Upload Validation

function validateFileUpload(file: File) {
  // Size check (5MB max)
  const maxSize = 5 * 1024 * 1024
  if (file.size > maxSize) {
    throw new Error('File too large (max 5MB)')
  }

  // Type check
  const allowedTypes = ['image/jpeg', 'image/png', 'image/gif']
  if (!allowedTypes.includes(file.type)) {
    throw new Error('Invalid file type')
  }

  // Extension check
  const allowedExtensions = ['.jpg', '.jpeg', '.png', '.gif']
  const extension = file.name.toLowerCase().match(/\.[^.]+$/)?.[0]
  if (!extension || !allowedExtensions.includes(extension)) {
    throw new Error('Invalid file extension')
  }

  return true
}

Verification Steps

All user inputs validated with schemas
File uploads restricted (size, type, extension)
No direct use of user input in queries
Whitelist validation (not blacklist)
Error messages don't leak sensitive info

3. SQL Injection Prevention

❌ NEVER Concatenate SQL

// DANGEROUS - SQL Injection vulnerability
const query = `SELECT * FROM users WHERE email = '${userEmail}'`
await db.query(query)

✅ ALWAYS Use Parameterized Queries

// Safe - parameterized query
const { data } = await supabase
  .from('users')
  .select('*')
  .eq('email', userEmail)

// Or with raw SQL
await db.query(
  'SELECT * FROM users WHERE email = $1',
  [userEmail]
)

Verification Steps

All database queries use parameterized queries
No string concatenation in SQL
ORM/query builder used correctly
Supabase queries properly sanitized

4. Authentication & Authorization

JWT Token Handling

// ❌ WRONG: localStorage (vulnerable to XSS)
localStorage.setItem('token', token)

// ✅ CORRECT: httpOnly cookies
res.setHeader('Set-Cookie',
  `token=${token}; HttpOnly; Secure; SameSite=Strict; Max-Age=3600`)

Authorization Checks

export async function deleteUser(userId: string, requesterId: string) {
  // ALWAYS verify authorization first
  const requester = await db.users.findUnique({
    where: { id: requesterId }
  })

  if (requester.role !== 'admin') {
    return NextResponse.json(
      { error: 'Unauthorized' },
      { status: 403 }
    )
  }

  // Proceed with deletion
  await db.users.delete({ where: { id: userId } })
}

Row Level Security (Supabase)

-- Enable RLS on all tables
ALTER TABLE users ENABLE ROW LEVEL SECURITY;

-- Users can only view their own data
CREATE POLICY "Users view own data"
  ON users FOR SELECT
  USING (auth.uid() = id);

-- Users can only update their own data
CREATE POLICY "Users update own data"
  ON users FOR UPDATE
  USING (auth.uid() = id);

Verification Steps

Tokens stored in httpOnly cookies (not localStorage)
Authorization checks before sensitive operations
Row Level Security enabled in Supabase
Role-based access control implemented
Session management secure

5. XSS Prevention

Sanitize HTML

import DOMPurify from 'isomorphic-dompurify'

// ALWAYS sanitize user-provided HTML
function renderUserContent(html: string) {
  const clean = DOMPurify.sanitize(html, {
    ALLOWED_TAGS: ['b', 'i', 'em', 'strong', 'p'],
    ALLOWED_ATTR: []
  })
  return <div dangerouslySetInnerHTML={{ __html: clean }} />
}

Content Security Policy

// next.config.js
const securityHeaders = [
  {
    key: 'Content-Security-Policy',
    value: `
      default-src 'self';
      script-src 'self' 'unsafe-eval' 'unsafe-inline';
      style-src 'self' 'unsafe-inline';
      img-src 'self' data: https:;
      font-src 'self';
      connect-src 'self' https://api.example.com;
    `.replace(/\s{2,}/g, ' ').trim()
  }
]

Verification Steps

User-provided HTML sanitized
CSP headers configured
No unvalidated dynamic content rendering
React's built-in XSS protection used

6. CSRF Protection

CSRF Tokens

import { csrf } from '@/lib/csrf'

export async function POST(request: Request) {
  const token = request.headers.get('X-CSRF-Token')

  if (!csrf.verify(token)) {
    return NextResponse.json(
      { error: 'Invalid CSRF token' },
      { status: 403 }
    )
  }

  // Process request
}

SameSite Cookies

res.setHeader('Set-Cookie',
  `session=${sessionId}; HttpOnly; Secure; SameSite=Strict`)

Verification Steps

CSRF tokens on state-changing operations
SameSite=Strict on all cookies
Double-submit cookie pattern implemented

7. Rate Limiting

API Rate Limiting

import rateLimit from 'express-rate-limit'

const limiter = rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 100, // 100 requests per window
  message: 'Too many requests'
})

// Apply to routes
app.use('/api/', limiter)

Expensive Operations

// Aggressive rate limiting for searches
const searchLimiter = rateLimit({
  windowMs: 60 * 1000, // 1 minute
  max: 10, // 10 requests per minute
  message: 'Too many search requests'
})

app.use('/api/search', searchLimiter)

Verification Steps

Rate limiting on all API endpoints
Stricter limits on expensive operations
IP-based rate limiting
User-based rate limiting (authenticated)

8. Sensitive Data Exposure

Logging

// ❌ WRONG: Logging sensitive data
console.log('User login:', { email, password })
console.log('Payment:', { cardNumber, cvv })

// ✅ CORRECT: Redact sensitive data
console.log('User login:', { email, userId })
console.log('Payment:', { last4: card.last4, userId })

Error Messages

// ❌ WRONG: Exposing internal details
catch (error) {
  return NextResponse.json(
    { error: error.message, stack: error.stack },
    { status: 500 }
  )
}

// ✅ CORRECT: Generic error messages
catch (error) {
  console.error('Internal error:', error)
  return NextResponse.json(
    { error: 'An error occurred. Please try again.' },
    { status: 500 }
  )
}

Verification Steps

No passwords, tokens, or secrets in logs
Error messages generic for users
Detailed errors only in server logs
No stack traces exposed to users

9. Blockchain Security (Solana)

Wallet Verification

import { verify } from '@solana/web3.js'

async function verifyWalletOwnership(
  publicKey: string,
  signature: string,
  message: string
) {
  try {
    const isValid = verify(
      Buffer.from(message),
      Buffer.from(signature, 'base64'),
      Buffer.from(publicKey, 'base64')
    )
    return isValid
  } catch (error) {
    return false
  }
}

Transaction Verification

async function verifyTransaction(transaction: Transaction) {
  // Verify recipient
  if (transaction.to !== expectedRecipient) {
    throw new Error('Invalid recipient')
  }

  // Verify amount
  if (transaction.amount > maxAmount) {
    throw new Error('Amount exceeds limit')
  }

  // Verify user has sufficient balance
  const balance = await getBalance(transaction.from)
  if (balance < transaction.amount) {
    throw new Error('Insufficient balance')
  }

  return true
}

Verification Steps

Wallet signatures verified
Transaction details validated
Balance checks before transactions
No blind transaction signing

10. Dependency Security

Regular Updates

# Check for vulnerabilities
npm audit

# Fix automatically fixable issues
npm audit fix

# Update dependencies
npm update

# Check for outdated packages
npm outdated

Lock Files

# ALWAYS commit lock files
git add package-lock.json

# Use in CI/CD for reproducible builds
npm ci  # Instead of npm install

Verification Steps

Dependencies up to date
No known vulnerabilities (npm audit clean)
Lock files committed
Dependabot enabled on GitHub
Regular security updates

Security Testing

Automated Security Tests

// Test authentication
test('requires authentication', async () => {
  const response = await fetch('/api/protected')
  expect(response.status).toBe(401)
})

// Test authorization
test('requires admin role', async () => {
  const response = await fetch('/api/admin', {
    headers: { Authorization: `Bearer ${userToken}` }
  })
  expect(response.status).toBe(403)
})

// Test input validation
test('rejects invalid input', async () => {
  const response = await fetch('/api/users', {
    method: 'POST',
    body: JSON.stringify({ email: 'not-an-email' })
  })
  expect(response.status).toBe(400)
})

// Test rate limiting
test('enforces rate limits', async () => {
  const requests = Array(101).fill(null).map(() =>
    fetch('/api/endpoint')
  )

  const responses = await Promise.all(requests)
  const tooManyRequests = responses.filter(r => r.status === 429)

  expect(tooManyRequests.length).toBeGreaterThan(0)
})

Pre-Deployment Security Checklist

Before ANY production deployment:

Secrets: No hardcoded secrets, all in env vars
Input Validation: All user inputs validated
SQL Injection: All queries parameterized
XSS: User content sanitized
CSRF: Protection enabled
Authentication: Proper token handling
Authorization: Role checks in place
Rate Limiting: Enabled on all endpoints
HTTPS: Enforced in production
Security Headers: CSP, X-Frame-Options configured
Error Handling: No sensitive data in errors
Logging: No sensitive data logged
Dependencies: Up to date, no vulnerabilities
Row Level Security: Enabled in Supabase
CORS: Properly configured
File Uploads: Validated (size, type)
Wallet Signatures: Verified (if blockchain)

Resources

Remember: Security is not optional. One vulnerability can compromise the entire platform. When in doubt, err on the side of caution.