---
applyTo: '**'
description: 'Comprehensive secure coding standards based on OWASP Top 10 2025, with 55+ anti-patterns, detection regex, framework-specific fixes for modern web and backend frameworks, and AI/LLM security guidance.'
---

# Security Standards

Comprehensive security rules for web application development. Every anti-pattern includes a severity classification, detection method, OWASP 2025 reference, and corrective code examples.

**Severity levels:**

- **CRITICAL** — Exploitable vulnerability. Must be fixed before merge.
- **IMPORTANT** — Significant risk. Should be fixed in the same sprint.
- **SUGGESTION** — Defense-in-depth improvement. Plan for a future iteration.

---

## OWASP Top 10 — 2025 Quick Reference

| # | Category | Key Mitigation |
|---|----------|----------------|
| A01 | Broken Access Control | Auth middleware on every endpoint, RBAC, ownership checks |
| A02 | Security Misconfiguration | Security headers, no debug in prod, no default credentials |
| A03 | Software Supply Chain Failures *(NEW)* | `npm audit`, lockfile integrity, SBOM, SLSA provenance |
| A04 | Cryptographic Failures | Argon2id/bcrypt for passwords, TLS everywhere, no secrets in code |
| A05 | Injection | Parameterized queries, input validation, no raw HTML with user input |
| A06 | Insecure Design | Threat modeling, secure design patterns, abuse case testing |
| A07 | Authentication Failures | Rate-limit login, secure session management, MFA |
| A08 | Software or Data Integrity Failures | SRI for CDN scripts, signed artifacts, no insecure deserialization |
| A09 | Security Logging and Alerting Failures | Log security events, no PII in logs, correlation IDs, active alerting |
| A10 | Mishandling of Exceptional Conditions *(NEW)* | Handle all errors, no stack traces in prod, fail-secure |

---

## Injection Anti-Patterns (I1-I8)

### I1: SQL Injection via String Concatenation

- **Severity**: CRITICAL
- **Detection**: `\$\{.*\}.*(?:SELECT|INSERT|UPDATE|DELETE|FROM|WHERE)`
- **OWASP**: A05

```typescript
// BAD
const unsafeResult = await db.query(`SELECT * FROM users WHERE id = ${userId}`);

// GOOD — parameterized query
const safeResult = await db.query('SELECT * FROM users WHERE id = $1', [userId]);
```

### I2: NoSQL Injection (MongoDB Operator Injection)

- **Severity**: CRITICAL
- **Detection**: `\{\s*\$(?:gt|gte|lt|lte|ne|in|nin|regex|where|exists)`
- **OWASP**: A05

```typescript
// BAD — attacker sends { "password": { "$gt": "" } }
const user = await User.findOne({ username: req.body.username, password: req.body.password });

// GOOD — validate and cast input types
const username = String(req.body.username);
const password = String(req.body.password);
const user = await User.findOne({ username });
const valid = user && await verifyPassword(user.passwordHash, password);
```

### I3: Command Injection (exec with User Input)

- **Severity**: CRITICAL
- **Detection**: `(?:exec|execSync|execFile|execFileSync)\s*\(.*(?:req\.|params\.|query\.|body\.)`
- **OWASP**: A05

```typescript
// BAD — shell interpolation, sync call blocks the event loop
import { execFileSync } from 'node:child_process';
const unsafeOutput = execFileSync('sh', ['-c', `ls -la ${req.query.dir}`]);

// GOOD — async execFile, arguments array, no shell, bounded time/output
import { execFile } from 'node:child_process';
import { promisify } from 'node:util';
const pExecFile = promisify(execFile);

const dir = String(req.query.dir ?? '');
if (!dir || dir.startsWith('-')) throw new Error('Invalid directory');
const { stdout: safeOutput } = await pExecFile('ls', ['-la', '--', dir], {
  timeout: 5_000,      // fail fast on hung processes
  maxBuffer: 1 << 20,  // 1 MiB cap to prevent memory exhaustion
});

// BEST — allowlist validation on top of the async, bounded call above
const allowedDirs = ['/data', '/public'];
if (!allowedDirs.includes(dir)) throw new Error('Invalid directory');
```

Prefer async `execFile`/`spawn` over `execFileSync` in server handlers: the sync variant blocks Node's event loop and can amplify DoS impact. Always pass a `timeout` and `maxBuffer` to bound execution.

### I4: XSS via Unsanitized HTML Rendering

- **Severity**: CRITICAL
- **Detection**: `(?:v-html|\[innerHTML\]|dangerouslySetInner|bypassSecurityTrust)`
- **OWASP**: A05

Applies to all frontend frameworks. Each has an API that bypasses default XSS protection:

- **React**: `dangerouslySetInnerHTML` prop with raw user content
- **Angular**: `[innerHTML]` binding or `bypassSecurityTrustHtml` with unsanitized input
- **Vue**: `v-html` directive with user-controlled content

```typescript
// GOOD — sanitize with DOMPurify before rendering any raw HTML
import DOMPurify from 'dompurify';
const clean = DOMPurify.sanitize(userContent);

// BEST — use text interpolation when HTML is not needed
// React:   {userContent}
// Angular: {{ userContent }}
// Vue:     {{ userContent }}
```

### I5: SSRF via User-Controlled URLs

- **Severity**: CRITICAL
- **Detection**: `fetch\((?:req\.|params\.|query\.|body\.|url|href)`
- **OWASP**: A01

```typescript
// BAD
const data = await fetch(req.body.url);

// GOOD — scheme allowlist + hostname allowlist + DNS/IP validation (see TOCTOU note)
import { promises as dns } from 'node:dns';

function isPrivateIP(ip: string): boolean {
  // Normalize IPv4-mapped IPv6 (e.g., ::ffff:127.0.0.1 → 127.0.0.1)
  const normalized = ip.startsWith('::ffff:') ? ip.slice(7) : ip;
  // IPv4 private/reserved/loopback ranges
  if (/^(10\.|172\.(1[6-9]|2\d|3[01])\.|192\.168\.|127\.|0\.|169\.254\.)/.test(normalized)) return true;
  // IPv6 loopback, link-local (fe80::/10), and unique-local
  if (/^(::1|fe[89ab]|fc|fd)/i.test(normalized)) return true;
  return false;
}

const parsed = new URL(req.body.url);
if (parsed.protocol !== 'https:') throw new Error('Only HTTPS allowed');
const allowedHosts = ['api.example.com', 'cdn.example.com'];
if (!allowedHosts.includes(parsed.hostname)) throw new Error('Host not allowed');
// Resolve all A/AAAA records to prevent DNS rebinding via multiple IPs
const resolved = await dns.lookup(parsed.hostname, { all: true });
if (resolved.length === 0 || resolved.some(({ address }) => isPrivateIP(address))) {
  throw new Error('Private or reserved IPs not allowed');
}
// Note: for production, pin the resolved IP in the HTTP client to prevent
// TOCTOU rebinding between this check and fetch(). See undici Agent docs.
const data = await fetch(parsed.toString(), { redirect: 'error' });
```

### I6: Path Traversal in File Operations

- **Severity**: CRITICAL
- **Detection**: `(?:readFile|readFileSync|createReadStream|path\.join)\s*\(.*(?:req\.|params\.|query\.|body\.)`
- **OWASP**: A01

```typescript
// BAD
const file = fs.readFileSync(`/data/${req.params.filename}`);

// GOOD — resolve and validate within allowed directory
import path from 'path';
const basePath = '/data';
const filePath = path.resolve(basePath, req.params.filename);
if (!filePath.startsWith(basePath + path.sep)) throw new Error('Path traversal detected');
const file = fs.readFileSync(filePath);
```

### I7: Template Injection

- **Severity**: CRITICAL
- **Detection**: `(?:render|compile|template)\s*\(.*(?:req\.|params\.|query\.|body\.)`
- **OWASP**: A05

```typescript
// BAD — user input as template source
const html = ejs.render(req.body.template, data);

// GOOD — predefined templates, user input only as data
const html = ejs.renderFile('./templates/page.ejs', { content: req.body.content });
```

### I8: XXE Injection (XML External Entity)

- **Severity**: CRITICAL
- **Detection**: `(?:parseXml|DOMParser|xml2js|libxmljs).*(?:req\.|body\.|file)`
- **OWASP**: A05

```typescript
// GOOD — disable external entities in XML parser
import { XMLParser } from 'fast-xml-parser';
const parser = new XMLParser({
  allowBooleanAttributes: true,
  processEntities: false,
  htmlEntities: false,
});
const result = parser.parse(req.body.xml);
```

---

## Authentication Anti-Patterns (AU1-AU8)

### AU1: JWT Algorithm Confusion (alg:none)

- **Severity**: CRITICAL
- **Detection**: `jwt\.verify\((?![^)]*\balgorithms\b)[^)]*\)`
- **OWASP**: A07

```typescript
// BAD — accepts any algorithm including "none"
const decoded = jwt.verify(token, secret);

// GOOD — enforce specific algorithm
const decoded = jwt.verify(token, publicKey, { algorithms: ['RS256'] });
```

### AU2: JWT Without Expiration Check

- **Severity**: CRITICAL
- **Detection**: `jwt\.sign\((?![^)]*\b(?:expiresIn|exp)\b)[^)]*\)`
- **OWASP**: A07

```typescript
// BAD — token never expires
const token = jwt.sign({ userId: user.id }, secret);

// GOOD — short-lived token
const token = jwt.sign({ userId: user.id }, secret, { expiresIn: '15m' });
```

### AU3: JWT Stored in localStorage

- **Severity**: IMPORTANT
- **Detection**: `localStorage\.setItem\(.*(?:token|jwt|auth|session)`
- **OWASP**: A07

```typescript
// BAD — accessible via XSS
localStorage.setItem('accessToken', token);

// GOOD — httpOnly cookie set by server
res.cookie('token', token, { httpOnly: true, secure: true, sameSite: 'strict' });
```

### AU4: Plaintext / Fast Hash for Passwords (MD5/SHA-1/SHA-256)

- **Severity**: CRITICAL
- **Detection**: `(?:createHash|md5|sha1|sha256)\s*\(.*password`
- **OWASP**: A04

```typescript
// BAD — fast hash, no salt
const sha256Hash = crypto.createHash('sha256').update(password).digest('hex');

// GOOD — Argon2id (OWASP recommended)
import { hash as argon2Hash, argon2id } from 'argon2';
const hashed = await argon2Hash(password, { type: argon2id, memoryCost: 65536, timeCost: 3 });
```

### AU5: Missing Brute-Force Protection on Login

- **Severity**: CRITICAL
- **Detection**: `(?:post|router\.post)\s*\(\s*['"]\/(?:login|signin|auth|register|reset)`
- **OWASP**: A07

```typescript
// BAD — no rate limiting
app.post('/api/auth/login', loginHandler);

// GOOD
import rateLimit from 'express-rate-limit';
const authLimiter = rateLimit({ windowMs: 15 * 60 * 1000, max: 5 });
app.post('/api/auth/login', authLimiter, loginHandler);
```

### AU6: Missing Session Regeneration on Login (Session Fixation)

- **Severity**: IMPORTANT
- **Detection**: `(?:session|req\.session)\s*\.\s*(?:userId|user|authenticated)\s*=`
- **OWASP**: A07

```typescript
// GOOD — regenerate session ID on successful login to prevent fixation
req.session.regenerate((err) => {
  if (err) return next(err);
  req.session.userId = user.id;
  req.session.save(next);
});
```

Related: on password change or elevation, also invalidate all other active sessions for the user (e.g., by bumping a `tokenVersion` column and rejecting sessions with a stale version, or by iterating the session store and destroying entries keyed to that user).

### AU7: OAuth Without State Parameter

- **Severity**: CRITICAL
- **Detection**: `authorize\?(?![^\n#]*\bstate=)[^\n#]*`
- **OWASP**: A07

```typescript
// GOOD — include state parameter for CSRF protection
const state = crypto.randomBytes(32).toString('hex');
session.oauthState = state;
const authUrl = `https://provider.com/authorize?client_id=${clientId}&redirect_uri=${redirectUri}&state=${state}`;
```

### AU8: Missing PKCE for Public OAuth Clients

- **Severity**: IMPORTANT
- **Detection**: `(?:authorization_code|code).*(?!.*code_challenge)`
- **OWASP**: A07

Use PKCE (Proof Key for Code Exchange) with S256 challenge method for all public clients (SPAs, mobile).

---

## Authorization Anti-Patterns (AZ1-AZ6)

### AZ1: Missing Auth Middleware on New Endpoints

- **Severity**: CRITICAL
- **Detection**: `(?:app|router)\.\w+\s*\(\s*['"]\/api\/(?:admin|users|settings)`
- **OWASP**: A01

```typescript
// BAD
router.delete('/api/users/:id', deleteUser);

// GOOD
router.delete('/api/users/:id', authenticate, authorize('admin'), deleteUser);
```

### AZ2: Client-Side Only Authorization

- **Severity**: CRITICAL
- **Detection**: Component guards without server-side checks
- **OWASP**: A01

Frontend guards are UX only. ALWAYS verify on server.

### AZ3: IDOR (Insecure Direct Object Reference)

- **Severity**: CRITICAL
- **Detection**: `params\.(?:id|userId|orderId)` without ownership check
- **OWASP**: A01

```typescript
// GOOD — verify ownership
router.get('/api/orders/:orderId', authenticate, async (req, res) => {
  const order = await Order.findById(req.params.orderId);
  if (!order || order.userId !== req.user.id) {
    return res.status(404).json({ error: 'Not found' });
  }
  res.json(order);
});
```

### AZ4: Mass Assignment

- **Severity**: CRITICAL
- **Detection**: `(?:create|update|findOneAndUpdate)\s*\(\s*req\.body\s*\)`
- **OWASP**: A01

```typescript
// BAD
await User.findByIdAndUpdate(id, req.body);

// GOOD — explicitly pick allowed fields
const { name, email, avatar } = req.body;
await User.findByIdAndUpdate(id, { name, email, avatar });
```

### AZ5: Privilege Escalation via Role Parameter

- **Severity**: CRITICAL
- **Detection**: `req\.body\.role|req\.body\.isAdmin|req\.body\.permissions`
- **OWASP**: A01

```typescript
// GOOD — ignore role from input
const { name, email, password } = req.body;
const user = await User.create({ name, email, password, role: 'user' });
```

### AZ6: Missing Re-Authentication for Sensitive Operations

- **Severity**: IMPORTANT
- **Detection**: `(?:delete|destroy|remove).*(?:account|user|organization)` without re-auth
- **OWASP**: A01

Require current password before account deletion, email change, or other sensitive operations.

---

## Secrets Anti-Patterns (S1-S6)

### S1: Hardcoded API Keys / Tokens

- **Severity**: CRITICAL
- **Detection**: `(?:password|secret|api_key|token|apiKey)\s*[:=]\s*['"][A-Za-z0-9+/=]{8,}['"]`
- **OWASP**: A04

```typescript
// BAD
const API_KEY = 'sk_live_abc123def456';

// GOOD
const API_KEY = process.env.API_KEY;
```

### S2: .env Committed to Git

- **Severity**: CRITICAL
- **Detection**: `git ls-files .env` (should return empty)
- **OWASP**: A04

```gitignore
# .gitignore
.env
.env.local
.env.*.local
*.pem
*.key
```

### S3: Server Secrets Exposed to Client

- **Severity**: CRITICAL
- **Detection**: `NEXT_PUBLIC_.*(?:SECRET|PRIVATE|PASSWORD|KEY(?!.*PUBLIC))`
- **OWASP**: A02

```bash
# BAD
NEXT_PUBLIC_DATABASE_URL=postgresql://...

# GOOD
DATABASE_URL=postgresql://...
NEXT_PUBLIC_API_URL=https://api.example.com
```

Angular: do not put secrets in `environment.ts` files bundled into the client.

### S4: Default Credentials in Config

- **Severity**: CRITICAL
- **Detection**: `(?:admin|root|default|test).*(?:password|pass|pwd)\s*[:=]\s*['"](?:admin|root|password|1234|test)`
- **OWASP**: A02

Use environment variables with validation (zod schema).

### S5: Secrets in CI/CD Pipeline Logs

- **Severity**: IMPORTANT
- **Detection**: `(?:echo|console\.log|print).*(?:\$SECRET|\$TOKEN|\$PASSWORD|process\.env)`
- **OWASP**: A09

Use masked secrets in CI. Never echo environment variables containing secrets.

### S6: Sensitive Data in Error Responses / Stack Traces

- **Severity**: IMPORTANT
- **Detection**: `(?:stack|trace|query|sql).*(?:res\.json|res\.send|c\.JSON)`
- **OWASP**: A10

```typescript
// GOOD — generic error to client, details only in logs
app.use((err, req, res, _next) => {
  logger.error({ err, path: req.path, method: req.method });
  const isDev = process.env.NODE_ENV === 'development';
  res.status(500).json({
    error: 'Internal Server Error',
    ...(isDev && { message: err.message }),
  });
});
```

---

## Headers Anti-Patterns (H1-H8)

### H1: Missing Content-Security-Policy

- **Severity**: IMPORTANT
- **Detection**: Absence of `Content-Security-Policy` header
- **OWASP**: A02

### H2: CSP with unsafe-inline and unsafe-eval

- **Severity**: IMPORTANT
- **Detection**: `Content-Security-Policy.*(?:'unsafe-inline'|'unsafe-eval')`
- **OWASP**: A02

Use nonce-based CSP: `script-src 'self' 'nonce-{SERVER_GENERATED}'`

### H3: Missing Strict-Transport-Security

- **Severity**: IMPORTANT
- **Detection**: Absence of `Strict-Transport-Security` header
- **OWASP**: A02

Value: `max-age=31536000; includeSubDomains; preload`

### H4: Missing X-Content-Type-Options

- **Severity**: IMPORTANT
- **Detection**: Absence of `X-Content-Type-Options: nosniff`
- **OWASP**: A02

### H5: Missing X-Frame-Options

- **Severity**: IMPORTANT
- **Detection**: Absence of `X-Frame-Options` header
- **OWASP**: A02

Value: `DENY`. Also set `Content-Security-Policy: frame-ancestors 'none'`.

### H6: Permissive Referrer-Policy

- **Severity**: SUGGESTION
- **Detection**: `Referrer-Policy.*(?:unsafe-url|no-referrer-when-downgrade)`
- **OWASP**: A02

Use: `strict-origin-when-cross-origin`

### H7: Missing Permissions-Policy

- **Severity**: SUGGESTION
- **Detection**: Absence of `Permissions-Policy` header
- **OWASP**: A02

Value: `camera=(), microphone=(), geolocation=(), payment=()`

### H8: CORS Wildcard with Credentials

- **Severity**: CRITICAL
- **Detection**: `(?:cors|Access-Control-Allow-Origin).*\*`
- **OWASP**: A02

```typescript
// GOOD
app.use(cors({
  origin: ['https://app.example.com', 'https://staging.example.com'],
  credentials: true,
}));
```

---

## Frontend Anti-Patterns (FE1-FE8)

### FE1: Unsanitized HTML Rendering

- **Severity**: CRITICAL
- **Detection**: `(?:innerHTML|v-html|dangerouslySetInner)` without DOMPurify
- **OWASP**: A05

Always sanitize with DOMPurify before rendering user-controlled HTML. See I4.

### FE2: Dynamic Code Evaluation with User Input

- **Severity**: CRITICAL
- **Detection**: `eval\s*\(`
- **OWASP**: A05

Use structured data parsers (JSON.parse) instead.

### FE3: postMessage Without Origin Validation

- **Severity**: IMPORTANT
- **Detection**: `addEventListener\s*\(\s*['"]message['"].*(?!.*origin)`
- **OWASP**: A01

```typescript
window.addEventListener('message', (event) => {
  if (event.origin !== 'https://trusted.example.com') return;
  processData(event.data);
});
```

### FE4: Prototype Pollution

- **Severity**: IMPORTANT
- **Detection**: `(?:__proto__|constructor\.prototype|Object\.assign)\s*.*(?:req\.|body\.|query\.)`
- **OWASP**: A05

Validate and filter keys from user input before merging into objects.

### FE5: Open Redirect

- **Severity**: IMPORTANT
- **Detection**: `(?:window\.location|location\.href|router\.push)\s*=\s*(?:req\.|params\.|query\.)`
- **OWASP**: A01

```typescript
// GOOD — relative paths only
const redirect = new URLSearchParams(window.location.search).get('redirect');
if (redirect?.startsWith('/') && !redirect.startsWith('//')) {
  window.location.href = redirect;
}
```

### FE6: Sensitive Data in localStorage

- **Severity**: IMPORTANT
- **Detection**: `localStorage\.setItem\(.*(?:token|session|credit|ssn|password)`
- **OWASP**: A07

Use httpOnly cookies for tokens.

### FE7: Missing CSRF Token

- **Severity**: IMPORTANT
- **Detection**: POST/PUT/DELETE forms without CSRF token or SameSite cookie
- **OWASP**: A01

Use double-submit cookie or synchronizer token. Next.js Server Actions have built-in CSRF via Origin header.

### FE8: Client-Only Input Validation

- **Severity**: IMPORTANT
- **Detection**: Form validation only in frontend
- **OWASP**: A05

ALWAYS validate on server too. Use zod, joi, or class-validator.

---

## Dependencies Anti-Patterns (D1-D5)

### D1: Known Vulnerable Dependency

- **Severity**: CRITICAL
- **Detection**: `npm audit --audit-level=high` exits non-zero
- **OWASP**: A03

### D2: Lockfile Out of Sync

- **Severity**: IMPORTANT
- **Detection**: `npm ci` fails
- **OWASP**: A08

### D3: Typosquatting Risk

- **Severity**: IMPORTANT
- **Detection**: Manual review of new dependency names
- **OWASP**: A03

### D4: Postinstall Scripts in New Dependency

- **Severity**: IMPORTANT
- **Detection**: `"postinstall"` in new dependency's package.json
- **OWASP**: A03

### D5: Unpinned Versions in Production

- **Severity**: SUGGESTION
- **Detection**: `":\s*["']\*["']|":\s*["']latest["']`
- **OWASP**: A03

---

## API Anti-Patterns (AP1-AP6)

### AP1: New Endpoint Without Rate Limiting

- **Severity**: IMPORTANT
- **OWASP**: A05

### AP2: GraphQL Without Depth Limiting

- **Severity**: IMPORTANT
- **Detection**: `new ApolloServer` without depth/complexity limits
- **OWASP**: A05

```typescript
import depthLimit from 'graphql-depth-limit';
const server = new ApolloServer({
  schema,
  validationRules: [depthLimit(5)],
  introspection: process.env.NODE_ENV !== 'production',
});
```

### AP3: File Upload Without Validation

- **Severity**: IMPORTANT
- **Detection**: `multer|formidable|busboy` without type/size checks
- **OWASP**: A05

```typescript
const upload = multer({
  dest: 'uploads/',
  limits: { fileSize: 5 * 1024 * 1024 },
  fileFilter: (req, file, cb) => {
    const allowed = ['image/jpeg', 'image/png', 'image/webp'];
    cb(null, allowed.includes(file.mimetype));
  },
});
```

### AP4: Webhook Without Signature Verification

- **Severity**: CRITICAL
- **OWASP**: A08

Always verify webhook signatures (Stripe, GitHub HMAC, etc.).

### AP5: API Exposing Internal Info

- **Severity**: IMPORTANT
- **Detection**: `(?:stack|trace|query|sql).*(?:res\.json|res\.send)`
- **OWASP**: A10

### AP6: Missing Request Body Size Limit

- **Severity**: IMPORTANT
- **Detection**: `express\.json\(\)` without `limit`
- **OWASP**: A05

```typescript
app.use(express.json({ limit: '100kb' }));
```

---

## AI/LLM Security Anti-Patterns (AI1-AI3)

### AI1: Prompt Injection via User Input

- **Severity**: CRITICAL
- **Detection**: User input concatenated into LLM prompts without sanitization
- **OWASP**: A05 (Injection)

```typescript
// BAD — user input directly in prompt
const response = await llm.complete(`Summarize this: ${userInput}`);

// GOOD — structured input with system/user message separation
const response = await llm.complete({
  system: "You are a summarization assistant. Only summarize the provided text.",
  user: userInput,
});
```

### AI2: LLM Output Used in SQL/Shell Without Sanitization

- **Severity**: CRITICAL
- **Detection**: LLM response passed to `db.query()`, `exec()`, or template literals without validation
- **OWASP**: A05 (Injection)

Never trust LLM output as safe. Treat it as untrusted user input — parameterize queries, escape shell arguments, sanitize HTML before rendering.

### AI3: Missing Output Validation from LLM Responses

- **Severity**: IMPORTANT
- **Detection**: LLM response rendered or executed without schema validation
- **OWASP**: A08 (Software or Data Integrity Failures)

Validate LLM output against expected schemas (Zod, JSON Schema) before using in application logic. Reject responses that don't match expected structure.

---

## Logging Anti-Patterns (L1-L4)

### L1: Security Events Not Logged

- **Severity**: IMPORTANT
- **OWASP**: A09

Log: auth failures, access denied, rate limit hits, input validation failures, password changes.

### L2: Sensitive Data in Logs

- **Severity**: CRITICAL
- **Detection**: `(?:log|logger)\.\w+\(.*(?:password|token|secret|ssn|credit)`
- **OWASP**: A09

```typescript
import pino from 'pino';
const logger = pino({ redact: ['req.headers.authorization', 'req.body.password'] });
```

### L3: Missing Trace IDs

- **Severity**: SUGGESTION
- **OWASP**: A09

### L4: Log Injection

- **Severity**: IMPORTANT
- **Detection**: `console\.log\(.*\+.*(?:req\.|user\.|body\.)`
- **OWASP**: A09

Use structured logging (JSON, auto-escaped) instead of string concatenation.

---

## Framework-Specific: React / Next.js (RX1-RX4)

### RX1: Server Action Without Auth

- **Severity**: CRITICAL
- **Detection**: `'use server'` function without `auth()` or session check
- **OWASP**: A01

```typescript
'use server';
import { auth } from '@/auth';
export async function deleteUser(id: string) {
  const session = await auth();
  if (!session?.user || session.user.role !== 'admin') throw new Error('Unauthorized');
  await db.user.delete({ where: { id } });
}
```

### RX2: process.env Without NEXT_PUBLIC_ in Client

- **Severity**: IMPORTANT
- **Detection**: `'use client'` file accessing `process.env` without `NEXT_PUBLIC_`
- **OWASP**: A02

### RX3: RSC Serialization Leaking Data

- **Severity**: IMPORTANT
- **OWASP**: A01

Pick only needed fields before passing DB objects to Client Components.

### RX4: middleware.ts Not Protecting API Routes

- **Severity**: IMPORTANT
- **Detection**: `config.matcher` not covering `/api/`
- **OWASP**: A01

---

## Framework-Specific: Angular (NG1-NG3)

### NG1: bypassSecurityTrustHtml with User Input

- **Severity**: CRITICAL
- **Detection**: `bypassSecurityTrust(?:Html|Script|Style|Url|ResourceUrl)`
- **OWASP**: A05

Sanitize with DOMPurify BEFORE calling bypassSecurityTrust.

### NG2: Template Expression Injection

- **Severity**: IMPORTANT
- **OWASP**: A05

Do not use JitCompilerFactory with user-controlled templates.

### NG3: HttpInterceptor Not Attaching Auth

- **Severity**: IMPORTANT
- **OWASP**: A07

Use a centralized `HttpInterceptorFn` for auth tokens.

---

## Framework-Specific: Express (EX1-EX4)

### EX1: Missing helmet.js

- **Severity**: IMPORTANT
- **OWASP**: A02

```typescript
import helmet from 'helmet';
app.use(helmet());
app.disable('x-powered-by');
```

### EX2: express.json() Without Body Size Limit

- **Severity**: IMPORTANT
- **OWASP**: A05

```typescript
app.use(express.json({ limit: '100kb' }));
```

### EX3: Cookie Without Secure Flags

- **Severity**: IMPORTANT
- **OWASP**: A07

```typescript
res.cookie('session', value, {
  httpOnly: true, secure: true, sameSite: 'strict', maxAge: 3600000, path: '/',
});
```

### EX4: Error Handler Exposing Stack Trace

- **Severity**: IMPORTANT
- **OWASP**: A10

Only expose error details in development mode.

---

## Framework-Specific: Go (GO1-GO3)

### GO1: math/rand for Security Operations

- **Severity**: CRITICAL
- **Detection**: `math/rand` import in security-related files
- **OWASP**: A04

Use `crypto/rand` for cryptographically secure random values.

### GO2: TLS InsecureSkipVerify

- **Severity**: CRITICAL
- **Detection**: `InsecureSkipVerify:\s*true`
- **OWASP**: A04

Use system CA pool (default) instead.

### GO3: String Interpolation in SQL

- **Severity**: CRITICAL
- **Detection**: `fmt\.Sprintf\s*\(.*(?:SELECT|INSERT|UPDATE|DELETE|FROM|WHERE)`
- **OWASP**: A05

```go
// GOOD — parameterized
db.Where("id = ?", userID).Find(&user)
```

---

## Security Headers Template

### helmet.js (Express)

```typescript
import helmet from 'helmet';

app.use(helmet({
  contentSecurityPolicy: {
    directives: {
      defaultSrc: ["'self'"],
      scriptSrc: ["'self'"],
      styleSrc: ["'self'"],
      imgSrc: ["'self'", "data:", "https:"],
      fontSrc: ["'self'"],
      connectSrc: ["'self'"],
      frameAncestors: ["'none'"],
      objectSrc: ["'none'"],
      baseUri: ["'self'"],
      formAction: ["'self'"],
      upgradeInsecureRequests: [],
    },
  },
  hsts: { maxAge: 31536000, includeSubDomains: true, preload: true },
  frameguard: { action: 'deny' },
  referrerPolicy: { policy: 'strict-origin-when-cross-origin' },
  crossOriginOpenerPolicy: { policy: 'same-origin' },
  crossOriginResourcePolicy: { policy: 'same-origin' },
}));
app.disable('x-powered-by');
```

---

## JWT Validation Checklist

1. Verify signature with expected algorithm — reject `alg: none`
2. Enforce algorithm: `algorithms: ['RS256']` or `['ES256']`
3. Check `exp` — reject expired tokens
4. Check `iat` — reject tokens issued too far in the past
5. Check `aud` — reject tokens not intended for this service
6. Check `iss` — reject tokens from unknown issuers
7. Store in httpOnly cookie — not localStorage
8. Use short-lived access tokens (15 min) + refresh token rotation
9. Rotate signing keys periodically

---

## Secure Cookie Flags

```
Set-Cookie: session=value; HttpOnly; Secure; SameSite=Strict; Path=/; Max-Age=3600
```

| Flag | Purpose | When to use |
|------|---------|-------------|
| `HttpOnly` | Not accessible via JavaScript (prevents XSS token theft) | Always |
| `Secure` | Only sent over HTTPS | Always |
| `SameSite=Strict` | Only sent on same-site requests (strongest CSRF) | Auth/session cookies |
| `SameSite=Lax` | Sent on top-level navigations (moderate CSRF) | Cookies that need cross-site top-level nav (e.g., OAuth return) |
| `Path=/` | Limit cookie scope | Always |
| `Max-Age` | Explicit expiration (prefer over `Expires`) | Always |

---

## Security Checklist

### Authentication and Sessions
- [ ] Passwords hashed with Argon2id or bcrypt (cost >= 12)
- [ ] JWT signed with RS256/ES256, algorithm enforced on verify
- [ ] Access tokens expire in <= 15 minutes
- [ ] Refresh tokens: one-time use, rotated, stored in httpOnly cookie
- [ ] Rate limiting on login, registration, and password reset
- [ ] Session regenerated after authentication
- [ ] MFA available for privileged accounts

### Authorization
- [ ] Every API endpoint has auth middleware
- [ ] Ownership checks on all resource access (prevent IDOR)
- [ ] Server-side authorization (frontend guards are UX only)
- [ ] Mass assignment prevented (explicit field selection)
- [ ] Re-authentication required for sensitive operations

### Input and Output
- [ ] All user input validated server-side (zod/joi/class-validator)
- [ ] Parameterized queries for all database operations
- [ ] HTML output sanitized (DOMPurify) when rendering user content
- [ ] Error responses do not expose stack traces in production

### Secrets
- [ ] No hardcoded secrets in source code
- [ ] `.env` files in `.gitignore`
- [ ] Server secrets not exposed to client (no NEXT_PUBLIC_ on secrets)
- [ ] Environment variables validated at startup

### Headers
- [ ] Content-Security-Policy configured (nonce-based preferred)
- [ ] Strict-Transport-Security with preload
- [ ] X-Content-Type-Options: nosniff
- [ ] X-Frame-Options: DENY
- [ ] Referrer-Policy: strict-origin-when-cross-origin
- [ ] Permissions-Policy restricting unused APIs
- [ ] CORS restricted to known origins

### Dependencies
- [ ] `npm audit` (or equivalent) passing in CI
- [ ] Lockfile committed and verified with `npm ci`
- [ ] New dependencies reviewed for typosquatting and postinstall scripts
- [ ] No wildcard or "latest" versions in production

### Logging
- [ ] Security events logged (auth failures, access denied, rate limits)
- [ ] No sensitive data in logs (passwords, tokens, PII)
- [ ] Structured logging with correlation IDs
- [ ] Alerts configured for anomalous patterns