A Fast-Lookup Reference for Core Web Security Concepts
This reference distills the highest-frequency web security concepts — the OWASP Top 10 categories, the correct defense for each major injection class, and the HTTP security headers every production app should set — into a form meant for quick lookup during code review or interview prep, not first-time learning. Each item below assumes you already understand the underlying mechanism from the other topics in this course and is phrased as a fast recall aid rather than a full explanation.
Cricket analogy: A quick reference is like a bowler's laminated field-placement card tucked into a pocket during a match — not for learning the game from scratch, but for a fast glance to confirm the right setup for a specific batter.
OWASP Top 10 (2021) — One-Line Recall
A01 Broken Access Control: verify per-resource authorization, not just authentication. A02 Cryptographic Failures: use TLS everywhere, strong hashing (bcrypt/argon2) for passwords, never roll your own crypto. A03 Injection: use parameterized queries and ORM query builders, never string-concatenate untrusted input into a query or command. A04 Insecure Design: threat-model before coding, not after. A05 Security Misconfiguration: disable debug mode and verbose errors in production, harden default configs. A06 Vulnerable and Outdated Components: run automated dependency scanning on every build. A07 Identification and Authentication Failures: rate-limit login, regenerate session on login, enforce MFA where possible. A08 Software and Data Integrity Failures: verify signatures on CI/CD artifacts and third-party scripts (subresource integrity). A09 Security Logging and Monitoring Failures: log auth events and anomalies with enough detail to reconstruct an incident. A10 Server-Side Request Forgery (SSRF): validate and allow-list outbound request destinations from server-side code.
Cricket analogy: Recalling the OWASP Top 10 in one line each is like a captain reviewing a laminated card of each bowler's go-to delivery before an over, rather than re-deriving each bowler's whole strategy from scratch.
# HTTP security headers quick-reference (set these in production)
Content-Security-Policy: default-src 'self'; script-src 'self'
X-Content-Type-Options: nosniff
X-Frame-Options: DENY
Strict-Transport-Security: max-age=63072000; includeSubDomains; preload
Referrer-Policy: strict-origin-when-cross-origin
Permissions-Policy: geolocation=(), microphone=(), camera=()
# Cookie flags for session/auth cookies
Set-Cookie: session=<token>; HttpOnly; Secure; SameSite=Strict
Common Vulnerability to Fix Mapping
For fast lookup during code review: SQL Injection maps to parameterized queries/prepared statements, never string concatenation. Reflected/Stored XSS maps to context-aware output encoding plus a strict Content-Security-Policy as defense-in-depth. CSRF maps to anti-CSRF tokens (synchronizer token pattern) plus SameSite cookie attributes. IDOR/BOLA maps to explicit per-request object-level ownership checks server-side. SSRF maps to allow-listing outbound destinations and blocking requests to internal/link-local IP ranges. Insecure deserialization maps to avoiding native deserialization of untrusted data entirely, or using signed/allow-listed formats. Open redirect maps to validating redirect targets against an allow-list of known-safe destinations rather than trusting a raw redirect_to parameter.
Cricket analogy: A vulnerability-to-fix mapping is like a bowler's mental lookup table — 'left-hander, footwork forward, bowl full and wide' — matching a specific batter type to a specific response, the same specific pairing a security engineer uses matching a flaw to its fix.
Use this page as a review aid, not a substitute for understanding root causes — if a mapping here doesn't immediately make sense, go back to the relevant deep-dive topic (secure coding checklist, penetration testing basics) rather than applying the fix by rote.
Security header values shown here are strict defaults for a typical single-origin app; a Content-Security-Policy that blocks all inline scripts, for example, will break apps that rely on inline event handlers or third-party embedded widgets — always test header changes in staging before enforcing them in production.
- This quick-reference assumes prior understanding and is meant for fast lookup, not first-time learning.
- OWASP Top 10 (2021): Broken Access Control, Cryptographic Failures, Injection, Insecure Design, Security Misconfiguration, Vulnerable Components, Auth Failures, Software/Data Integrity Failures, Logging/Monitoring Failures, SSRF.
- Core HTTP security headers: Content-Security-Policy, X-Content-Type-Options, X-Frame-Options, Strict-Transport-Security, Referrer-Policy, Permissions-Policy.
- Session/auth cookies should always set HttpOnly, Secure, and SameSite attributes.
- SQLi fixes to parameterized queries; XSS fixes to context-aware encoding plus CSP; CSRF fixes to anti-CSRF tokens plus SameSite cookies.
- IDOR/BOLA fixes to explicit server-side object-level ownership checks; SSRF fixes to outbound destination allow-listing.
- Test security header and policy changes in staging first, since strict defaults can break legitimate functionality like inline scripts or third-party widgets.
Practice what you learned
1. What is the canonical fix for SQL Injection according to this quick reference?
2. Which HTTP header is primarily used to prevent a page from being embedded in a malicious iframe (clickjacking)?
3. What three cookie attributes should always be set together on session/auth cookies?
4. What is the canonical fix for IDOR/BOLA according to this reference?
5. Why must security header changes like a strict CSP be tested in staging before production?
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