Core Code
Core Code Modern Dev Handbook
APPLICATION-SECURITY Contents
Security Foundations for Production Apps
Threat Modeling (Practical, Repeatable) OWASP Top 10 (Operator Lens) Defense in Depth (Layered Controls That Hold) Security Baselines and Checklists (What “Good” Looks Like) Secrets in Apps (Storage, Injection, Rotation) Logging Sensitive Data (Pitfalls and Redaction) Rate Limiting Patterns (Abuse and Resilience) Abuse Prevention (Bots, Fraud, Enumeration) HTTPS & TLS Realities (HSTS, Termination, Cert Ops) Secure Headers Baseline (Production Defaults)
Identity, Authentication, and Sessions
Sessions vs JWT (Production Tradeoffs) JWT Attack Patterns and Validation Pitfalls Password Hashing Ops (bcrypt/argon2 Parameters) OAuth2 Flows in Practice (Auth Code + PKCE) OIDC Internals (Discovery, JWKS, Claims) Token Revocation Strategies (What Actually Works) Refresh Token Abuse and Rotation Defenses API Key Management (Issuance, Rotation, Scoping) mTLS Basics (Service-to-Service Identity) Identity Boundary Design (Trust Zones)
Web Attacks and Practical Defenses
XSS in Production (Exploit Paths and CSP Hardening) CSRF (SameSite Reality vs Token Defenses) SSRF (Cloud Metadata Abuse and Egress Controls) Clickjacking (Frame Controls and UI Redress) SQL Injection (Production Defense Patterns) CORS Misconfigurations (Real-World Impact) CSP Practical Recipes (Deployable Policies) Secure Cookie Patterns (HttpOnly, Secure, SameSite) Request Validation Patterns (What to Validate Where) File Upload Hardening (Content Sniffing, AV, Storage)
Secure Delivery, Hardening, and Incident Response
Secure SDLC (Gates That Don’t Kill Delivery) Dependency Risks (Vulns, Updates, Policies) App Supply Chain (Lockfiles, Pinning, Review) Configuration Hardening (Safe Defaults Checklist) Security Monitoring Signals (Auth, Data, Network) Security Alert Design (Noise, Triage, Escalation) WAF Realities (What It Stops and What It Doesn’t) Credential Leak Runbook (Keys, Tokens, Passwords) Compromised Token Runbook (JWT/OAuth Sessions) Security Incident Response (Contain, Eradicate, Recover)

OAuth2 Flows in Practice (Auth Code + PKCE)

OAuth2 flows for production teams: which flow to use, how to avoid common misconfigs, and what to log and alert on.
On this page

Choose the Right Flow

  • Browser SPA: Authorization Code + PKCE
  • Server-side web app: Authorization Code
  • Service-to-service: Client Credentials
  • Devices: Device Code (when needed)

Production Checklist

  • Strict redirect URI allowlist (no wildcards).
  • Use PKCE for public clients.
  • Scope minimization (least privilege).
  • Short-lived access tokens + refresh token rotation.

Logging You Actually Need

Log fields:
- client_id
- grant_type
- user_id (if present)
- scopes granted
- redirect_uri (normalized)
- decision (allow/deny) + reason
- token_id / session_id hash

Failure Modes

  • Redirect URI abuse: token leakage → strict allowlist + normalize.
  • Over-scoped tokens: breach blast radius → per-client scopes.
  • No rotation: stolen refresh token persists → rotate + detect reuse.

Operational Test

Verify redirect rules:
- attempt auth with unregistered redirect_uri
- expect hard failure (no partial success)
OIDC Internals (Discovery, JWKS, Claims) →