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)

Secure Headers Baseline (Production Defaults)

Set a secure header baseline that survives real browsers: HSTS, X-Content-Type-Options, frame protections, referrer policy, and safe defaults.
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Baseline Headers (Practical)

  • Strict-Transport-Security (after HTTPS-only verified)
  • X-Content-Type-Options: nosniff
  • Referrer-Policy: strict-origin-when-cross-origin (common safe default)
  • X-Frame-Options or CSP frame-ancestors (prefer CSP if you have CSP)
  • Permissions-Policy (disable unused powerful features)

Nginx Example

add_header X-Content-Type-Options "nosniff" always;
add_header Referrer-Policy "strict-origin-when-cross-origin" always;
add_header X-Frame-Options "DENY" always;

# Enable HSTS only after you are sure HTTPS is correct everywhere
add_header Strict-Transport-Security "max-age=86400" always;

# Minimal Permissions-Policy example (adjust to your app needs)
add_header Permissions-Policy "geolocation=(), microphone=(), camera=()" always;

Verification

curl -sS -D - https://app.example.com/ -o /dev/null | egrep -i 
"strict-transport-security|x-content-type-options|referrer-policy|x-frame-options|permissions-policy"

Failure Modes

  • Headers not on error responses: use always flag so 4xx/5xx still include headers.
  • Multiple proxies: ensure headers are not stripped or duplicated incorrectly.
  • Clickjacking exceptions: if embedding is needed, use CSP frame-ancestors with allowlist.

Operational Tip

Track header baseline in CI: run the curl check on every release and fail if headers regress.