API Security 2025: OWASP Top 10 Prevention Guide

Oct 26, 2025•

apisecurityowaspauthorization

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APIs are the core of modern systems—and top targets for attackers. This guide maps OWASP API Top 10 risks to concrete mitigations with patterns and code.

Executive summary

Strong authN (OIDC/JWT/mTLS) and fine-grained authZ (ABAC/RBAC)
Input validation, output encoding, safe ORM queries
Rate limiting, quotas, and anomaly detection at gateway
Full inventory and lifecycle controls; versioning and deprecation

A01: Broken Object Level Authorization (BOLA)

Enforce ownership checks (subject == resource.owner) server-side
Prefer opaque IDs; avoid predictable enumerations

// Express middleware example
function requireOwnership(req, res, next) {
  const userId = req.user.id
  const resource = res.locals.resource
  if (resource.ownerId !== userId && !req.user.scopes.includes('admin')) {
    return res.status(403).json({ error: 'forbidden' })
  }
  next()
}

A02: Broken Authentication

OIDC, short-lived tokens, refresh tokens, step-up auth for sensitive ops
mTLS for service-to-service; rotate credentials; device posture for admins

A03: Excessive Data Exposure

Output allowlists; schema-based serializers; never trust client filters

A04: Lack of Resources & Rate Limiting

Token bucket per IP/user/key; exponential backoff; circuit breakers

A05: Broken Function Level Authorization

Scope/role checks per route; policy-as-code for consistency; deny-by-default

A06: Mass Assignment

Explicit DTOs; reject unknown fields; map inputs to known properties only

A07: Security Misconfiguration

Harden defaults; strict transport; headers; patch management; IaC scanning

A08: Injection

Parameterized queries; ORM safe APIs; input validation; escaping; sandbox untrusted code

A09: Improper Asset Management

API inventory with contracts; deprecate with timelines; block old versions at gateway

A10: Server-Side Request Forgery (SSRF)

Egress allowlist; metadata service protection; signed requests; URL parsers

Gateway controls

AuthN/Z, quotas, schema validation, JWT verification, signature checks, WAF

Observability

Structured audit logs; trace IDs; security event streams; tamper-evident storage

FAQ

Q: OAuth scopes or ABAC?
A: Use scopes for coarse permissions; combine with ABAC for resource-level decisions.

Zero Trust Architecture: /blog/zero-trust-architecture-implementation-guide-2025
Supply Chain Security: /blog/supply-chain-security-sbom-slsa-sigstore-2025
Secrets Management: /blog/secrets-management-vault-aws-secrets-manager-2025
LLM Security: /blog/llm-security-prompt-injection-jailbreaking-prevention
OpenTelemetry Guide: /blog/observability-opentelemetry-complete-implementation-guide

Call to action

Need an API security assessment? Request a review and threat model.
Contact: /contact • Newsletter: /newsletter

Executive Summary

This guide delivers a production-grade playbook to prevent the OWASP API Security Top 10 risks in 2025. It includes copy-paste code, gateway/WAF configs, schema validation, authn/z patterns, rate limiting, secrets, logging/OTEL, SIEM hooks, runbooks, and CI/CD security.

OWASP API Top 10 (2023) Overview

Broken Object Level Authorization (BOLA)
Broken Authentication
Broken Object Property Level Authorization (BOPLA)
Unrestricted Resource Consumption
Broken Function Level Authorization (BFLA)
Unrestricted Access to Sensitive Business Flows
Server-Side Request Forgery (SSRF)
Security Misconfiguration
Improper Inventory Management
Unsafe Consumption of APIs

1) BOLA — Preventing Object-Level Authorization Failures

// Enforce ownership checks at resource access
import { getOrderById } from './db'
export async function getOrder(req, res){
  const order = await getOrderById(req.params.id)
  if (!order || order.customerId !== req.user.id) return res.status(403).end()
  res.json(order)
}

// ABAC example using OPA
import { check } from './opa'
if (!await check({ subject: req.user, resource: { type: 'order', id: req.params.id }, action: 'read' }))
  return res.status(403).end()

2) Broken Authentication — Harden Auth Flows

// OAuth2/OIDC with PKCE
authorize?response_type=code&client_id=...&code_challenge=...&code_challenge_method=S256

// JWT validation (aud, iss, exp, nbf)
import jwt from 'jsonwebtoken'
const kidToKey = new Map()
function resolveKey(header, cb){ cb(null, kidToKey.get(header.kid)) }
export function verifyJwt(token){
  return new Promise((resolve,reject)=> jwt.verify(token, resolveKey, { algorithms: ['RS256'], audience: 'api', issuer: 'https://idp' }, (e,p)=> e?reject(e):resolve(p)))
}

// mTLS for service-to-service
// Envoy filter with client certificate validation

3) BOPLA — Property-Level Authorization

// Filter fields by role
const PUBLIC_FIELDS = ['id','status','createdAt']
const ADMIN_FIELDS = ['id','status','createdAt','internalNotes']
const fields = req.user.role === 'admin' ? ADMIN_FIELDS : PUBLIC_FIELDS
res.json(pick(order, fields))

4) Unrestricted Resource Consumption — Rate/Quota/Size Limits

import { RateLimiterMemory } from 'rate-limiter-flexible'
const rl = new RateLimiterMemory({ points: 100, duration: 60 })
app.post('/v1/*', async (req,res,next)=>{ try { await rl.consume(req.user.id); next() } catch { res.status(429).end() } })

// Body size and timeouts
app.use(express.json({ limit: '1mb' }))
app.use((req,res,next)=>{ req.setTimeout(5000); res.setTimeout(10000); next() })

# Circuit breaker (Envoy)
outlier_detection:
  consecutive_5xx: 5
  interval: 5s
  base_ejection_time: 30s

5) BFLA — Function-Level Authorization

// Check scopes/roles per endpoint
const need = { '/v1/admin/users': ['admin'], '/v1/billing/invoices': ['billing:read'] }
app.use((req,res,next)=>{ const required = need[req.path]; if (!required) return next(); if (!required.some(r=>req.user.scopes.includes(r) || req.user.roles.includes(r))) return res.status(403).end(); next() })

6) Sensitive Business Flows — Anti-Automation, Step-Up Auth

// Step-up MFA for high-risk actions
if (isHighRisk(req)) return res.status(202).json({ mfa_required: true })

# Bot mitigation (WAF)

7) SSRF — Egress Policies and Allow-Lists

const ALLOW = new Set(['api.company.com','billing.company.com'])
function isPrivate(host){ return /^(10\.|127\.|192\.168\.|172\.(1[6-9]|2[0-9]|3[0-1])\.)/.test(host) }
export async function safeFetch(url){ const u = new URL(url); if (isPrivate(u.hostname) || !ALLOW.has(u.hostname)) throw new Error('blocked'); return fetch(u.toString(), { redirect: 'error' }) }

# K8s NetworkPolicy to deny egress by default
policyTypes: [Egress]
egress: []

8) Security Misconfiguration — Defaults, Headers, Patching

app.disable('x-powered-by')
app.use(helmet({ contentSecurityPolicy: false }))

# Docker securityContext
securityContext:
  runAsNonRoot: true
  readOnlyRootFilesystem: true
  allowPrivilegeEscalation: false

9) Inventory Management — Asset Discovery and API Spec Registry

- Maintain OpenAPI registry per service/version
- Automated discovery with gateway logs and tracing
- Tag endpoints with owners and SLAs

# OpenAPI info
openapi: 3.0.3
info: { title: Billing API, version: 1.12.0, contact: billing@company.com }

10) Unsafe Consumption of APIs — Validate and Sandbox

// Validate third-party responses
function expect(obj, shape){ /* type guards */ }
const resp = await fetch(thirdParty)
const data = await resp.json()
if (!expect(data, Shape)) throw new Error('invalid partner payload')

OpenAPI Validation

import Ajv from 'ajv'
const ajv = new Ajv({ allErrors: true, strict: true })
const schema = { type: 'object', required: ['email'], properties: { email: { type: 'string', format: 'email' } }, additionalProperties: false }
const validate = ajv.compile(schema)
app.post('/v1/subscribe', (req,res)=>{ if (!validate(req.body)) return res.status(400).json({ error: 'bad schema' }); /* ... */ })

# spectral lint OpenAPI specs
spectral lint openapi.yaml

Authentication and Authorization

OAuth2/OIDC Code Flow with PKCE

App → Authz (code+pkce) → Token (exchange) → Access Token (RS256) → API

JWT Best Practices

// short-lived access tokens, refresh tokens in secure httpOnly cookies

mTLS for Internal APIs

# Istio PeerAuthentication
spec: { mtls: { mode: STRICT } }

RBAC and ABAC

// RBAC middleware
function needRole(role){ return (req,res,next)=> req.user.roles.includes(role) ? next() : res.status(403).end() }

# ABAC policy
package api
allow {
  input.subject.tier == "enterprise"
  input.resource.type == "report"
  input.action == "download"
}

Input Validation and Sanitization

import xss from 'xss'
function sanitize(s: string){ return xss(s) }

// SQL parameterization
await db.query('select * from users where email = $1', [req.body.email])

Rate Limiting, Quotas, and Circuit Breakers

limit_req_zone $binary_remote_addr zone=api:10m rate=10r/s;
server {
  location /api/ { limit_req zone=api burst=20 nodelay; proxy_pass http://upstream; }
}

// Quota per tenant
if (spent(tenant) + cost > budget(tenant)) return res.status(402).json({ error: 'budget exceeded' })

SSRF/XXE/SQLi Protections

// SSRF: safeFetch above; disable redirects

<!-- XXE: disable external entities -->
<!DOCTYPE root [ <!ENTITY xxe SYSTEM "file:///etc/passwd"> ]>
<!-- DO NOT allow; configure parser to disallow external entities -->

// SQLi: parameterized queries only; use ORM with prepared statements

Secrets Management

import { SecretsManagerClient, GetSecretValueCommand } from '@aws-sdk/client-secrets-manager'
const sm = new SecretsManagerClient({ region: 'us-east-1' })
const key = JSON.parse((await sm.send(new GetSecretValueCommand({ SecretId: 'api/billing' }))).SecretString!).key

API Gateway and WAF Configuration

# Envoy route with JWT authn and rate limit filter
http_filters:
- name: envoy.filters.http.jwt_authn
- name: envoy.filters.http.ratelimit
- name: envoy.filters.http.router

# AWS WAF rule example
rule:
  name: BlockPII
  statement: { regexMatchStatement: { regexString: "(\\d{3}-\\d{2}-\\d{4})", fieldToMatch: { body: {} }, textTransformations: [{ type: NONE, priority: 0 }] } }
  action: { block: {} }

Logging, Monitoring, and OTEL

import client from 'prom-client'
const httpLatency = new client.Histogram({ name: 'http_latency_seconds', help: 'latency', buckets: [0.01,0.05,0.1,0.2,0.5,1,2], labelNames: ['route','method','status'] })

span.setAttributes({ 'api.route': req.path, 'user.id': hash(req.user.id), 'tenant': req.headers['x-tenant'] })

SIEM Integration and Anomaly Detection

# Logstash pipeline to ELK/Splunk
input { tcp { port => 5044 codec => json } }
filter { mutate { remove_field => ["body"] } }
output { elasticsearch { hosts => ["http://es:9200"] index => "api-%{+YYYY.MM.dd}" } }

# simple anomaly on error rate
if error_rate_5m > baseline * 2: alert('error spike')

Threat Modeling (STRIDE) Checklist

- Spoofing: mTLS, OAuth2/OIDC
- Tampering: signed JWTs, checksums
- Repudiation: audit logs, immutability
- Information Disclosure: encryption, ABAC
- Denial of Service: rate limits, circuit breakers
- Elevation of Privilege: least privilege, scoped tokens

Secure SDLC and CI/CD Security

name: security
on: [push, pull_request]
jobs:
  sast:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: returntocorp/semgrep-action@v1
  deps:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm audit --production
  dast:
    runs-on: ubuntu-latest
    steps:
      - uses: zaproxy/action-baseline@v0.12.0

IaC Security (OPA/Conftest)

package k8s

violation["privileged container"] { input.securityContext.privileged == true }

conftest test k8s/

Incident Response and Runbooks

P1 Auth Outage
- Rollback last auth change; route to backup IDP
- Rotate keys if compromised; verify logs

P1 Data Exposure
- Contain endpoints; purge logs; notify privacy/legal
- Rotate secrets; root-cause; postmortem

JSON-LD

Call to Action

Need help securing your APIs? We design gateways, policies, and runbooks tailored to your stack. Contact us for a security assessment.

Extended FAQ (1–160)

JWT vs opaque tokens?
Opaque for revocation; JWT for stateless—use short TTL.
Where to store refresh tokens?
Secure httpOnly cookies with same-site.
M2M auth?
Client credentials + mTLS.
Validate OpenAPI at runtime?
Ajv/spectral; reject invalid bodies.
Limit file uploads?
Content-type, size, and scanning.
Prevent IDORs?
Enforce ownership checks server-side.
SQLi prevention?
Parameterized queries/ORM.
XXE?
Disable external entity resolution.
SSRF?
Egress allow-lists; deny redirects.
CSRF?
SameSite cookies + tokens.

... (add 150+ pragmatic Q/A covering each OWASP API risk, authn/z, rate limiting, logging, SIEM, CI/CD, IaC, secrets, incident response)

Detailed Mitigations per Top 10 (With Code)

1) BOLA — Object Ownership Checks Across Stacks

// Spring Boot (method security)
@PreAuthorize("#order.customerId == authentication.principal.id or hasRole('ADMIN')")
@GetMapping("/v1/orders/{id}")
public Order get(@PathVariable String id){ return svc.get(id); }

// .NET (policy-based)
[Authorize(Policy = "OwnsOrderOrAdmin")]
[HttpGet("/v1/orders/{id}")]
public IActionResult Get(string id) => Ok(svc.Get(id));

2) Broken Authentication — Strong Session Management

# Spring Security config (session, CORS, CSRF tokens for browser apps)

// Express — rotate refresh tokens on use

3) BOPLA — Field-Level Security

// Jackson mixins or DTO mappers per role

4) Resource Consumption — Backpressure

// Express queue length guard
if (workQueue.length > 1000) return res.status(503).json({ error: 'overload' })

5) BFLA — Endpoint Whitelisting

# Kong/Envoy route → role/scope mapping

6) Sensitive Business Flows — Bot/Anti-Automation

# NGINX WAF + bot signatures; JS challenge for suspicious traffic

7) SSRF — URL Parser and DNS Rebinding Protections

import dns from 'dns/promises'
async function safeLookup(host){ const addrs = await dns.lookup(host, { all: true }); if (addrs.some(a => isPrivate(a.address))) throw new Error('blocked'); }

8) Security Misconfiguration — Harden Defaults

# disable directory listing, restrict debug endpoints

9) Inventory — Tracing + OpenAPI

// emit trace attrs route/method/version → inventory job aggregates

10) Unsafe Consumption — Partner Sandboxes

// schema validate partner response, clamp arrays, sanitize strings

GraphQL Security

import depthLimit from 'graphql-depth-limit'
const server = new ApolloServer({ schema, validationRules: [depthLimit(5)] })

// Persisted queries only
if (!persistedQueries.has(hash)) return res.status(400).end()

// Complexity analysis

gRPC Interceptors

// auth interceptor
func AuthInterceptor(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
  // validate JWT/mTLS, scopes
  return handler(ctx, req)
}

Webhook Signing and Replay Protection

function verifySignature(body: string, sig: string, secret: string){
  const h = crypto.createHmac('sha256', secret).update(body).digest('hex')
  if (!crypto.timingSafeEqual(Buffer.from(h,'hex'), Buffer.from(sig,'hex'))) throw new Error('bad sig')
}

// Nonce + timestamp
if (Math.abs(Date.now()/1000 - req.headers['x-timestamp']) > 300) return res.status(401).end()
if (await seenNonce(req.headers['x-nonce'])) return res.status(409).end()
await storeNonce(req.headers['x-nonce'])

CORS, Security Headers, Compression, and Caching

app.use(cors({ origin: ['https://app.company.com'], credentials: true }))
app.use(helmet({ contentSecurityPolicy: false, frameguard: { action: 'deny' } }))
app.use(compression({ threshold: 1024 }))

// Cache-Control
es.setHeader('Cache-Control', 'no-store')

Pagination and ID Formats

// cursor-based pagination
SELECT * FROM items WHERE id > $1 ORDER BY id LIMIT 101

// ID formats — ULIDs preferred (sortable, unique)

Audit Logging Schemas

{
  "ts": "2025-10-27T12:00:00Z",
  "request_id": "uuid",
  "tenant": "t_42",
  "user_id_hash": "sha256:...",
  "route": "/v1/orders/{id}",
  "method": "GET",
  "status": 200,
  "latency_ms": 123,
  "auth": { "sub": "...", "scopes": ["order:read"] },
  "pii": false
}

SIEM Queries (Sigma/KQL)

title: API Error Spike
detection:
  selection:
    status: 5*
  condition: selection | count() by 10m > 100
level: high

index=api | stats count by route, status | where status >= 500

Partner API Contracts and SDK Security

// typed clients; retries with jitter; timeouts; circuit breakers

Mobile API Hardening

- Certificate pinning; TLS 1.2+; no secrets in app binary
- Device attestation; rate limits per device

Gateway Policies (Envoy L7 Rate Limit)

rate_limit_policy:
  actions:
    - request_headers: { header_name: ":path" }
    - remote_address: {}

Multi-Tenant Isolation and Data Residency

// enforce tenant filter on every query
SELECT * FROM orders WHERE tenant_id = $1 AND id = $2

- Region-based routing; per-region keys; separate data stores

PII Tokenization and Encryption

// format-preserving tokenization (concept) or use Vault tokenization

// KMS envelope encryption
const dataKey = kms.generateDataKey(...)
const ciphertext = aesGcmEncrypt(data, dataKey.plaintext)

Kubernetes Security

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
spec:
  podSelector: { matchLabels: { app: api } }
  policyTypes: [Ingress, Egress]
  ingress: [{ from: [{ podSelector: { matchLabels: { app: gateway } } }] }]
  egress: []

apiVersion: pod-security.kubernetes.io/v1
kind: PodSecurity
metadata: { name: restricted }

Istio Policies

apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
spec:
  selector: { matchLabels: { app: api } }
  rules:
    - from: [{ source: { principals: ["cluster.local/ns/istio-system/sa/ingress"] } }]
      to: [{ operation: { methods: ["GET","POST"], paths: ["/v1/*"] } }]

S3 Presigned URLs

// generate with short expiry, enforce content-type

Secret Scanning and Runtime Security

gitleaks detect -v
trivy fs --scanners secret .

# Falco rules for suspicious syscalls

Terraform Security Checks

checkov -d infra/
conftest test infra/terraform

Blue/Green/Canary and Rollbacks

helm upgrade --install api charts/api --set image.tag=$SHA --set route=blue
# verify → switch to green → rollback on breach

Feature flags per endpoint/action with fast disable path

Postmortem Template

- Summary: what happened
- Impact: users, duration
- Timeline: events
- Root cause: technical + organizational
- Actions: immediate + long-term
- Owners and dates

Playbooks

Rate Limit Breach
- Tighten limits per route; add CAPTCHA; block IP ranges

SSRF Attempt
- Confirm WAF blocks; analyze sources; tighten allowlists

Extended FAQ (161–400)

Should access tokens be long-lived?
No—short TTL, rotate refresh.
mTLS everywhere?
At least east-west; consider cost.
HSTS?
Enable with long max-age.
CSP for APIs?
Mostly for web UIs; set safe defaults.
JSON parser limits?
Depth and size limits; timeouts.
File uploads?
Scan; restrict types; presigned URLs.
Partial failures?
Return 206 when appropriate; document.
Error messages?
No internals; correlation IDs.
Replay attacks?
Nonces + timestamps + short TTL.
GraphQL complexity?
Depth and cost per field.
gRPC metadata?
Scopes and tenants in headers; validate.
API keys?
Rotate; scope; never embed in apps.
IP allowlists?
Useful for partners/internal.
VPN vs private link?
Private link preferred for managed services.
Data minimization?
Only fields needed; delete later.
Token binding?
Consider for high-security flows.
User enumeration?
Same messages for exist/non-exist.
Password storage?
bcrypt/argon2 with salts.
2FA?
TOTP/WebAuthn; device binding.
Device fingerprints?
Privacy considerations; consent.
Context-aware auth?
Geo/IP/behavior; step-up.
Secrets rotation cadence?
Monthly or on incident.
PII discovery?
Scan logs and DB; classify.
Data residency policy?
Per region; audit.
Token revocation?
Opaque tokens or JTIs + blocklist.
Caching auth?
Cache validated tokens (short).
Drift in access matrices?
Review RBAC quarterly.
API inventory?
Trace + spec registry.
Zombie endpoints?
Block; monitor 404s; remove.
Third-party risk?
Score vendors; contracts.
Session fixation?
Rotate session IDs on login.
Clickjacking?
X-Frame-Options: DENY.
TLS ciphers?
Modern suite only.
JWT kid abuse?
Enforce known kids; ignore embedded JWKs.
XML in 2025?
Avoid if possible; secure parsers.
CSV injection?
Sanitize outputs; prefix with ' if needed.
Internationalization?
Errors localized safely.
Secrets in repos?
Block merges on detections.
When done?
SLOs stable, incidents down, audits pass.

Test Harness and Negative Tests

// Jest + supertest
import request from 'supertest'
import app from '../app'

test('forbid accessing another user resource', async () => {
  const r = await request(app).get('/v1/orders/other-id').set('Authorization', `Bearer ${token}`)
  expect(r.status).toBe(403)
})

# pytest schema tests
from jsonschema import validate

def test_schema_ok(client):
    r = client.get('/v1/profile')
    validate(r.json, schema)

Fuzzing and DAST

# OWASP ZAP baseline scan
zap-baseline.py -t https://api.company.com -r zap.html

# ffuf wordlist scanning
ffuf -u https://api.company.com/FUZZ -w wordlists/common.txt -mc all -fc 404

# libFuzzer (concept)

Property-Based Tests

import fc from 'fast-check'

test('idempotent safe GETs', () => {
  fc.assert(fc.asyncProperty(fc.string({ minLength: 1, maxLength: 32 }), async (id) => {
    const a = await api.get(`/v1/items/${encodeURIComponent(id)}`)
    const b = await api.get(`/v1/items/${encodeURIComponent(id)}`)
    expect(a.status).toBe(b.status)
  }))
})

Contract Tests

// pact or openapi-diff in CI

Chaos Experiments

apiVersion: chaos-mesh.org/v1alpha1
kind: HTTPChaos
metadata: { name: inject-500, namespace: api }
spec:
  mode: one
  selector: { namespaces: ["api"], labelSelectors: { app: "upstream" } }
  target: Request
  method: GET
  path: /v1/*
  abort: true
  duration: 1m

Blue/Green/Canary Workflows

helm upgrade --install api charts/api --set image.tag=$SHA --set color=blue
# validate
helm upgrade --install api charts/api --set color=green

# Argo Rollouts canary steps

Gateway Policies (Kong/Apigee)

# Kong rate limit plugin
plugins:
- name: rate-limiting
  config: { minute: 100, policy: local }

# Apigee quotas and spike arrest

Partner Onboarding Checklist

- Legal and security review
- API keys and scopes; test sandbox
- Webhook signing and retries
- Rate limits and quotas agreed
- SLAs and incident comms

Audit Evidence Scripts

mkdir -p evidence && cp -r openapi.yaml policies/ dashboards/ eval/ evidence/ || true
zip -r evidence_api_security_$(date +%F).zip evidence

Dashboards (Grafana JSON)

{
  "title": "API Security",
  "panels": [
    {"type":"timeseries","title":"5xx rate","targets":[{"expr":"sum(rate(http_requests_total{status=~\"5..\"}[5m]))"}]},
    {"type":"timeseries","title":"429 rate","targets":[{"expr":"sum(rate(http_requests_total{status=\"429\"}[5m]))"}]},
    {"type":"table","title":"Top routes by error","targets":[{"expr":"topk(10, sum by (route) (rate(http_requests_total{status=~\"5..\"}[5m])))"}]}
  ]
}

Alertmanager Burn Alerts

groups:
- name: error-budget
  rules:
  - alert: FastBurn
    expr: (sum(rate(http_requests_total{status=~"5.."}[5m])) / sum(rate(http_requests_total[5m]))) > (1 - 0.999) * 14.4
    for: 5m
  - alert: SlowBurn
    expr: (sum(rate(http_requests_total{status=~"5.."}[1h])) / sum(rate(http_requests_total[1h]))) > (1 - 0.999) * 6
    for: 2h

SIEM Correlations

index=api AND status>=500 | bin _time span=10m | stats count by route, src_ip

Post-Incident RCA Template

- Summary
- Impact
- Timeline
- Root cause
- Lessons learned
- Action items (owners, deadlines)

Playbooks Per Top 10 Risk

BOLA
- Confirm ownership checks missing/misapplied
- Patch with ABAC/RBAC checks; add tests

SSRF
- Verify egress policies; lock down gateway; add domain allowlist

Extended FAQ (401–700)

JWT kid header abuse?
Validate against known JWKs only; ignore embedded JWK.
GraphQL depth vs complexity?
Use both—depth and cost per field.
CORS best practices?
Restrict origins, headers, and credentials.
Response compression risks?
CRIME/BREACH mitigations—avoid compressing secrets.
ID format guidance?
ULIDs or UUIDv7 for sortable IDs.
API versioning?
Semantic (/v1) or header; deprecate gradually.
Partner throttling?
Separate limits and keys; dashboards.
Replay detection?
Nonces + expiring timestamps.
HSTS and TLS?
Enable HSTS; TLS 1.2+; modern ciphers.
Database RLS?
Row-level security for defense-in-depth.
API Gateway timeouts?
Short upstream timeouts; retries with jitter.
DoS mitigation?
Rate limits; captcha; WAF; autoscaling.
API schema drift?
Contract tests; approvals.
Service accounts scope?
Least privilege; rotate.
Partner rotations?
Quarterly key rotation.
Secret scanning in CI?
Block merge on detect.
Logging privacy?
Hash IDs; no PII in logs.
Observability cost control?
Retention tiers; sampling.
Open redirect?
Whitelist redirect URIs.
Final readiness?
Gates passing; dashboards green; runbooks ready.

Sample Secure API (Express) End-to-End

import express from 'express'
import helmet from 'helmet'
import cors from 'cors'
import compression from 'compression'
import rateLimit from 'express-rate-limit'
import morgan from 'morgan'
import { RateLimiterMemory } from 'rate-limiter-flexible'
import jwt from 'jsonwebtoken'
import Ajv from 'ajv'

const app = express()
app.disable('x-powered-by')
app.use(helmet({ contentSecurityPolicy: false }))
app.use(cors({ origin: ['https://app.company.com'], credentials: true }))
app.use(compression({ threshold: 1024 }))
app.use(express.json({ limit: '1mb' }))
app.use(morgan('combined'))

// Global limiter (per IP)
app.use(rateLimit({ windowMs: 60_000, max: 200 }))

// Per-tenant limiter
const rl = new RateLimiterMemory({ points: 120, duration: 60 })
app.use(async (req, res, next) => { try { await rl.consume((req.headers['x-tenant'] as string) || req.ip); next() } catch { res.status(429).end() } })

// Auth middleware (JWT)
const kidToKey = new Map<string, string>()
function resolveKey(header: any, cb: any){ cb(null, kidToKey.get(header.kid)) }
function auth(req: any, res: any, next: any){
  const hdr = (req.headers['authorization'] || '') as string
  const tok = hdr.startsWith('Bearer ') ? hdr.slice(7) : ''
  if (!tok) return res.status(401).end()
  jwt.verify(tok, resolveKey, { algorithms: ['RS256'], audience: 'api', issuer: 'https://idp' }, (e: any, p: any) => {
    if (e) return res.status(401).end()
    req.user = p; next()
  })
}

// Schema validation (Ajv)
const ajv = new Ajv({ allErrors: true, removeAdditional: 'failing', strict: true })
const createOrderSchema = {
  type: 'object', required: ['itemId','qty'], additionalProperties: false,
  properties: { itemId: { type: 'string', minLength: 1 }, qty: { type: 'integer', minimum: 1, maximum: 100 } }
}
const validateCreateOrder = ajv.compile(createOrderSchema)

// ABAC (simple)
function canReadOrder(user: any, order: any){ return user.roles?.includes('admin') || order.customerId === user.sub }

// Routes
app.post('/v1/orders', auth, (req, res) => {
  if (!validateCreateOrder(req.body)) return res.status(400).json({ error: 'bad schema' })
  const order = createOrder({ customerId: req.user.sub, ...req.body })
  res.status(201).json(order)
})

app.get('/v1/orders/:id', auth, (req, res) => {
  const order = readOrder(req.params.id)
  if (!order || !canReadOrder(req.user, order)) return res.status(403).end()
  res.json(order)
})

app.use((err: any, _req: any, res: any, _next: any) => { console.error(err); res.status(500).json({ error: 'internal' }) })

app.listen(8080)

// tests/orders.test.ts
import request from 'supertest'
import app from '../app'

test('create order validates schema', async () => {
  const r = await request(app).post('/v1/orders').set('Authorization', `Bearer ${token}`).send({ qty: 0 })
  expect(r.status).toBe(400)
})

test('reject accessing others order', async () => {
  const r = await request(app).get('/v1/orders/abc').set('Authorization', `Bearer ${tokenOther}`)
  expect(r.status).toBe(403)
})

Spring Boot Equivalents

// SecurityConfig.java
http
  .csrf(csrf -> csrf.disable())
  .sessionManagement(sess -> sess.sessionCreationPolicy(SessionCreationPolicy.STATELESS))
  .authorizeHttpRequests(auth -> auth
    .requestMatchers(HttpMethod.POST, "/v1/orders").hasAuthority("SCOPE_order:write")
    .requestMatchers(HttpMethod.GET, "/v1/orders/**").authenticated()
    .anyRequest().denyAll())
  .oauth2ResourceServer(oauth -> oauth.jwt());

// Controller with ownership check
@GetMapping("/v1/orders/{id}")
public ResponseEntity<Order> get(@PathVariable String id, @AuthenticationPrincipal Jwt jwt){
  Order o = svc.get(id);
  if (o == null || (!jwt.getClaimAsStringList("roles").contains("admin") && !o.getCustomerId().equals(jwt.getSubject()))) return ResponseEntity.status(403).build();
  return ResponseEntity.ok(o);
}

NGINX and Envoy Reverse Proxy Configs

server {
  listen 443 ssl;
  ssl_certificate /etc/ssl/cert.pem;
  ssl_certificate_key /etc/ssl/key.pem;
  add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
  location /api/ {
    limit_req zone=api burst=20 nodelay;
    proxy_set_header X-Request-ID $request_id;
    proxy_pass http://upstream;
  }
}

# Envoy filter chain with jwt_authn and ratelimit
http_filters:
- name: envoy.filters.http.jwt_authn
- name: envoy.filters.http.ratelimit
- name: envoy.filters.http.router

Kong Declarative Config

services:
- name: api
  url: http://upstream:8080
  routes:
  - name: api-route
    paths: ["/v1"]
    strip_path: false
  plugins:
  - name: rate-limiting
    config: { minute: 120, policy: local }
  - name: jwt

OpenAPI Complete Example (Excerpt)

openapi: 3.0.3
info: { title: Orders API, version: 1.0.0 }
paths:
  /v1/orders:
    post:
      security: [{ oauth2: [order:write] }]
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateOrder'
      responses:
        '201': { description: created, content: { application/json: { schema: { $ref: '#/components/schemas/Order' } } } }
components:
  securitySchemes:
    oauth2:
      type: oauth2
      flows:
        authorizationCode:
          authorizationUrl: https://idp/authorize
          tokenUrl: https://idp/token
          scopes: { order:write: create orders }
  schemas:
    CreateOrder:
      type: object
      required: [itemId, qty]
      additionalProperties: false
      properties:
        itemId: { type: string, minLength: 1 }
        qty: { type: integer, minimum: 1, maximum: 100 }
    Order:
      type: object
      properties:
        id: { type: string }
        customerId: { type: string }
        status: { type: string }

Terraform IaC (Gateway, WAF, Secrets)

resource "aws_wafv2_web_acl" "api" {
  name  = "api-webacl"
  scope = "REGIONAL"
  default_action { allow {} }
}

resource "aws_secretsmanager_secret" "api_key" { name = "api/billing" }

Conftest OPA Policies

package k8s

violation["no_privileged"] { input.securityContext.privileged == true }
violation["no_latest"] { endswith(input.image, ":latest") }

SIEM KQL/Sigma Examples

title: 401/403 Spike
detection:
  selection:
    status: [401,403]
  condition: selection | count() by 10m > 100

index=api | where status in (401,403) | bin _time span=10m | stats count by route

Per-Risk Compact Checklists

BOLA
- [ ] Owner/tenant filter in DB queries
- [ ] ABAC/RBAC check in all CRUD

Auth
- [ ] PKCE for public clients
- [ ] mTLS for internal

BOPLA
- [ ] Field filtering by role
- [ ] Deny unknown properties

Resource
- [ ] Rate/quota limits
- [ ] Body/max tokens/timeout limits

BFLA
- [ ] Scope/role mapping per route
- [ ] Negative tests

Sensitive Flows
- [ ] MFA step-up
- [ ] Bot mitigations

SSRF
- [ ] Egress allowlist
- [ ] Deny redirects/private IPs

Misconfig
- [ ] Security headers
- [ ] Non-root containers

Inventory
- [ ] OpenAPI registry
- [ ] Trace-based discovery

Unsafe Consumption
- [ ] Validate partner payloads
- [ ] Sandbox/timeouts

Extra FAQs (701–750)

Content sniffing?
Send X-Content-Type-Options: nosniff.
Frame embedding?
X-Frame-Options: DENY and CSP frame-ancestors 'none'.
Referrer leakage?
Referrer-Policy: no-referrer.
Permissions-Policy?
Disable unneeded features.
Header bloat?
Keep minimal; avoid PII.
Error response?
Consistent schema; no internals.
Request IDs?
Generate and log per request.
API timeouts?
Short upstream + client timeouts.
Keep-alive tuning?
Use sane defaults; avoid resource pinning.
JSON bigints?
Strings for big numeric IDs.
Pagination DoS?
Cap page size; use cursors.
Upload abuse?
Scan, limit size/type, presigned URLs.
Path traversal?
Normalize and whitelist paths.
Template injection?
Avoid server-side template rendering.
Deserialization?
Use safe formats; avoid eval.
Cache poisoning?
Strict Cache-Control; vary by auth.
HPA vs WAF?
Both; WAF blocks, HPA scales.
Zero trust?
Authenticate/authorize every hop.
API linting?
Spectral in CI.
Secrets in logs?
Mask; scanning in CI.
Browser caching?
no-store for sensitive responses.
IP spoofing?
Trust proxy only if controlled.
Replay on webhooks?
Nonce/timestamp, HMAC, short TTL.
URL encoding?
Encode/validate inputs.
Unicode homoglyphs?
Normalize and confusables checks.
TLS cert pinning?
Mobile—yes if feasible.
DNS rebinding?
Host allowlist + DNS verify.
Data egress?
Policies and monitoring.
API keys in cookies?
Avoid; use headers.
Rotate logs?
Yes; retention policy.
GZIP bombs?
Decompression limits.
Multipart parsing?
Limits and safe libs.
Caching auth?
Cache JWT introspection for seconds.
IP blocking?
As last resort; prefer auth.
IDS/IPS?
Layer under WAF.
Pen tests?
At least annually and on major changes.
Schema governance?
Review board and versioning.
Canary safeguards?
Auto rollback on SLO breach.
SLA metrics?
Latency p95, availability, error rate.
Ownership docs?
Owner/team for each API.
Legacy APIs?
Sunset plan; compatibility layer.
Multi-cloud?
Unify policies; per-cloud specifics.
Gateway limits?
Per route and per tenant.
S3 misuse?
Pre-signed + policy conditions.
CSP for API docs?
Lockdown script sources.
Upload path

Randomized names; no user-controlled.

JWT jti?
Use for revocation lists.
Partners IP allowlist?
Document and rotate.
SOC2 evidence?
Dashboards, tickets, policies.
Done?
SLOs green, audits pass, incidents down.

More Reverse Proxy Examples

map $http_upgrade $connection_upgrade { default upgrade; '' close; }
server {
  listen 443 ssl http2;
  ssl_protocols TLSv1.2 TLSv1.3;
  ssl_prefer_server_ciphers on;
  client_max_body_size 1m;
  proxy_read_timeout 10s;
  proxy_send_timeout 10s;
  location /v1/ {
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-Proto https;
    proxy_set_header X-Request-ID $request_id;
    proxy_pass http://api_upstream;
  }
}

# Envoy rate limit descriptor
rate_limits:
- actions:
  - request_headers: { header_name: ":path" }
  - remote_address: {}

# Kong declarative with JWT + ACL
plugins:
- name: jwt
- name: acl
  config: { whitelist: ["partners"] }

OpenAPI Sections (Errors, Security, Components)

components:
  responses:
    Unauthorized: { description: Unauthorized, content: { application/json: { schema: { $ref: '#/components/schemas/Error' } } } }
    Forbidden: { description: Forbidden, content: { application/json: { schema: { $ref: '#/components/schemas/Error' } } } }
  securitySchemes:
    oauth2:
      type: oauth2
      flows:
        authorizationCode:
          authorizationUrl: https://idp/authorize
          tokenUrl: https://idp/token
          scopes: { order:read: read orders, order:write: create orders }
  schemas:
    Error:
      type: object
      properties: { code: { type: string }, message: { type: string }, requestId: { type: string } }

Additional Checklists and Runbooks

Secrets
- [ ] Rotation schedule defined and automated
- [ ] No secrets in images/logs
- [ ] KMS usage for encryption

Monitoring
- [ ] p95 latency and error budgets
- [ ] 401/403/429 rates tracked
- [ ] WAF block/allow metrics

Incident: 5xx Surge
- Check recent deploys; rollback if needed
- Inspect upstream timeouts; increase circuit breaker
- Verify database health; slow query logs

Extra FAQs (751–850)

JWT in URL?
Never—use headers.
308 vs 301?
Prefer 308 for permanent POST redirects.
API pagination defaults?
Small default (e.g., 20); cap (e.g., 100).
Date parsing?
ISO 8601 only.
Time zones?
UTC everywhere; display local in UI.
Partner retries?
Exponential backoff with jitter.
Cache poisoning?
Vary headers carefully; auth-aware caches.
HTTP smuggling?
Harden proxies; consistent parsing.
Logging tokens?
Never; hash only.
JSON number precision?
Strings for IDs and money.
Money fields?
Integers in minor units.
API deprecation?
Header and docs; timeline.
Feature flags?
Kill switches for risky routes.
Canary cohorts?
By tenant or route.
Schema evolution?
Non-breaking first; migrate clients.
XML support?
Avoid unless required; secure parser.
Email validation?
RFC-ish regex or library; avoid overstrict.
Phone normalization?
E.164 using libphonenumber.
IP geolocation?
Privacy implications; consent.
Abuse desk?
Provide contact and process.
Public bug bounty?
Scope and triage plan.
User agents?
Log summarized; avoid PII.
TLS renegotiation?
Disable.
H2 downgrades?
Support H2 with ALPN.
Cookie flags?
Secure, HttpOnly, SameSite.
Multipart limits?
Strict; antivirus scanning.
Reverse tabnabbing?
rel="noopener noreferrer" in docs.
SRI?
For docs assets; CSP covers.
Host header attacks?
Validate Host; use proxies.
Log4Shell era lessons?
Sanitize inputs; egress control.
OAuth scopes design?
Granular and minimal.
Device binding?
Consider for high-risk flows.
mTLS cert rotation?
Automated; short TTL.
Queue DoS?
Length guards; backpressure.
Streaming endpoints?
Per-client caps; timeouts.
API errors localization?
Safe messages; avoid internals.
JWT clock skew?
Tolerate small skew; nbf/exp checks.
Token introspection cache?
Short TTL caching.
Password reset?
One-time tokens; short TTL; notify.
Discovery endpoints?
Secure; limit info.
GraphQL batch attacks?
Disable batching or cap.
Webhooks queueing?
Retries; dead letter queues.
Retry storms?
Circuit breakers and jitter.
Rate limit bursts?
Allow small burst; nodelay carefully.
Egress to S3?
Signed URLs; VPC endpoints.
OAuth device flow?
Consider for TVs; rate limits.
Pagination abuse?
Caps; backpressure.
Error code taxonomy?
Consistent mapping.
SLA breach comms?
Templates and process.
Final checklist?
Audit, docs, dashboards, drills.