A defensive tour of the OWASP Top 10 — SQL injection, broken access control, authentication and session failures, XSS, SSRF and command injection, misconfiguration, and the secure development lifecycle. Each risk is taught the same way: how it works, how to prevent it in code, and how to detect it.
Before you start — test only what you own
This course is for building secure apps and testing systems you own or are explicitly authorized to test. Practice hands-on techniques against a local deliberately-vulnerable app like OWASP Juice Shop or DVWA, plus an intercepting proxy (Burp Suite or OWASP ZAP). Unauthorized testing is illegal.
How the Web Is Attacked
Before you can secure a web app you must see it as an attacker does — as raw HTTP requests you can read and modify. Set up a lab and an intercepting proxy, legally.
SQL Injection
When user input is concatenated into a database query, an attacker can rewrite that query. See how injection works, then kill it for good with parameterized queries.
Broken Access Control
The #1 web risk: apps that check who you are but not what you’re allowed to do. See IDOR and missing authorization, and enforce access control on the server every time.
Authentication & Session Failures
Weak logins and sloppy sessions hand over accounts. Store passwords correctly, resist credential stuffing, and manage sessions so a stolen cookie can’t roam free.
Cross-Site Scripting (XSS)
XSS runs the attacker’s JavaScript in your users’ browsers. Learn the three types, stop it with output encoding and a Content Security Policy, and know where frameworks help.
SSRF & Command Injection
Some inputs make the server itself attack — fetching internal URLs (SSRF) or running shell commands. Both come from trusting input; both are stopped by strict allowlists.
Misconfiguration & Vulnerable Components
Most breaches don’t need a clever exploit — just a default password, an exposed panel, a leaked secret, or an outdated library. Close the easy doors and patch your dependencies.
The Secure Development Lifecycle
Security isn’t a final audit — it’s built in throughout. Bake threat modeling, automated testing, and dependency scanning into the pipeline so flaws are caught before release.