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)

mTLS Basics (Service-to-Service Identity)

mTLS basics for operators: when to use it, how to deploy safely, certificate rotation, and common failure modes in service meshes and gateways.
On this page

What mTLS Gives You

  • Encryption in transit
  • Service identity (client cert proves who is calling)
  • Optional policy enforcement at the boundary

When to Use mTLS

  • Service-to-service traffic in zero-trust networks
  • Admin/control plane endpoints
  • Internal APIs where API keys are too weak

Operational Checklist

  • Define certificate issuer/CA ownership and rotation cadence.
  • Set certificate lifetime short enough to limit blast radius.
  • Roll out gradually with dual-stack acceptance (mTLS optional → required).
  • Monitor handshake failures explicitly.

Common Failure Modes

  • Clock skew: cert not yet valid / expired.
  • CA mismatch: wrong trust bundle deployed.
  • Rotation outage: old certs removed too early.

Quick TLS Sanity Check

# Server cert dates
echo | openssl s_client -connect api.internal:443 -servername api.internal 2>/dev/null 
| openssl x509 -noout -dates -subject
Identity Boundary Design (Trust Zones) →