Offensive Level 3 — Intermediate

Web & Application Security

🎯 Goal

Understand how web applications work, how they break, and how to test them. This is the core of bug bounty hunting, web penetration testing, and securing modern applications.

🔑 Key Skills to Learn

  • HTTP/HTTPS Deep Dive: Methods (GET, POST, PUT, DELETE), headers (Cookie, User-Agent, CORS), status codes, caching.
  • Browser Developer Tools: Inspect element, Network tab, Console, Storage (cookies, local storage).
  • Input Validation & Injection Attacks: SQL injection (SQLi), Cross-Site Scripting (XSS), Command Injection, LDAP Injection.
  • Authentication & Session Flaws: Broken authentication, session fixation, JWT weaknesses, OAuth misconfigurations.
  • Access Control Issues: IDOR (Insecure Direct Object References), privilege escalation, CORS misconfigurations.
  • Cross-Site Request Forgery (CSRF): How it works and protections (CSRF tokens, SameSite cookies).
  • Server-Side Request Forgery (SSRF): Exploiting server-side requests to internal services.
  • File Upload Vulnerabilities: Unrestricted file upload, bypassing filters, RCE via uploads.
  • OWASP Top 10 (Full List): Apply every item in practical scenarios.
  • API Security Testing: REST, GraphQL, common API vulnerabilities (JWT flaws, mass assignment, rate limiting).
  • Burp Suite Basics: Proxy, Repeater, Intruder, extensions.

🛠️ Essential Tools & Technologies

Tool Purpose
Burp Suite Community Edition Intercepting proxy, request manipulation, automation.
OWASP ZAP Open-source intercepting proxy and scanner.
Ffuf / GoBuster Fast web fuzzer for directories, subdomains, parameters.
SQLmap Automated SQL injection detection and exploitation.
Nuclei Template-based vulnerability scanner for known patterns.
Postman / Insomnia API testing clients.
Browser DevTools Built-in network and debugger panels.
HackBar (browser extension) Quick encoding, payload generation (Burp's Repeater can also do this).

📖 Free Learning Resources

  • PortSwigger Web Security Academy – The gold standard: free, in-depth labs for every OWASP category. Link
  • OWASP Top 10 – Reference documentation. Link
  • Bugcrowd University – Free content on common vulnerability classes and report writing. Link
  • Hacker101 – Free video lessons and CTF challenges. Link
  • TryHackMe – Web Fundamentals Path – Rooms: "OWASP Top 10", "Web Hacking", "Burp Suite". Link
  • API Security Fundamentals (APISec University) – Free course on API security testing. Link
  • Google Gruyere – A deliberately vulnerable web app with tutorials. Link

🔗 Roadmap Placement

  • Prerequisites: Core Security Concepts, Linux, Networking. You need to understand HTTP, Linux terminal, and basic security principles.
  • Directly Enables: Bug Bounty hunting, Web Application Penetration Testing, and parts of Red Teaming (initial access via web exploitation). It also helps Blue Teamers recognize web-based attacks in logs.
  • Next Step: Within the Offensive path, you can move to Advanced Web Exploitation & Bug Bounty Methodology, or to Red Teaming / Internal Penetration Testing.