A structured, hands-on security lab designed to help developers, penetration testers, and security researchers understand and practice real-world Cross-Site Scripting (XSS) vulnerabilities in a safe and controlled environment.
This project simulates common insecure coding patterns found in modern web applications and provides progressively harder challenges across multiple XSS categories.
This lab environment contains 10 carefully designed challenges covering the most common XSS attack surfaces in web applications.
- How XSS vulnerabilities are introduced in real applications
- How client-side and server-side sinks behave
- How input sanitization and filtering can be bypassed
- How context (HTML, attribute, JavaScript, SVG) affects exploitation
| Type | Description |
|---|---|
| Reflected XSS | User input is immediately returned in the HTTP response without proper sanitization |
| DOM-Based XSS | Vulnerability exists in client-side JavaScript sinks |
| Filter Evasion XSS | Input sanitization bypass techniques targeting HTML/JS filters |
| Contextual XSS | Injection depending on HTML attributes, JS strings, or URL contexts |
| Advanced Injection Vectors | SVG, iframe, and JavaScript URI-based injection techniques |
Focus: Understanding basic reflection and DOM sinks
| # | Lab | Type | Concept |
|---|---|---|---|
| 1 | Reflected XSS — Basic Input Reflection | Reflected | Unsafe output encoding |
| 2 | Reflected XSS — Template Literal Injection | Reflected | JavaScript template context |
| 3 | DOM XSS — location.hash Sink | DOM | Client-side unsafe parsing |
Focus: Bypassing filters and abusing DOM sinks
| # | Lab | Type | Concept |
|---|---|---|---|
| 4 | HTML Tag Filtering Bypass | Bypass | Broken sanitization logic |
| 5 | DOM XSS — document.write Sink | DOM | Unsafe DOM rendering |
| 6 | Reflected XSS with HTML Encoding Weakness | Reflected | Partial encoding bypass |
Focus: Context-aware injection and restricted environments
| # | Lab | Type | Concept |
|---|---|---|---|
| 7 | JS Context XSS with Character Restrictions | Reflected | JavaScript escaping limitations |
| 8 | Attribute Context XSS (href Injection) | Attribute | HTML attribute breaking |
| 9 | SVG-based Script Injection | SVG | Event-based execution vectors |
| 10 | Iframe Data URI Injection | iframe | sandbox & URI-based execution |
By completing this lab series, you will gain practical experience in:
- Identifying XSS vulnerabilities in different execution contexts
- Understanding how browsers interpret HTML, JS, and DOM sinks
- Exploiting weak or broken sanitization mechanisms
- Bypassing common blacklist-based filters
- Crafting payloads for restricted environments
- Recognizing real-world insecure coding patterns
This project is strictly intended for educational and research purposes only.
All challenges are designed to run in a local or explicitly authorized environment.
Any misuse of the techniques demonstrated in these labs against unauthorized systems is strictly prohibited.
The author assumes no responsibility for improper use of this material.
To begin exploring the labs, visit:
👉 https://the0x-pwn.github.io/lab-xss/
- Modern web browser (Chrome / Firefox)
- Developer Tools enabled
- Basic understanding of HTML & JavaScript
- Start from Easy → Medium → Hard
- Inspect source code and DOM changes using DevTools
- Analyze input reflection points carefully
- Test payload variations in different contexts
- Understand why each payload works, not just how
Before attempting advanced labs, it is recommended to understand:
- HTML injection basics
- JavaScript execution contexts
- DOM manipulation fundamentals
- Browser encoding behavior (HTML / URL / JS encoding)
This lab series was built to simulate real-world insecure patterns often found in:
- Legacy web applications
- Misconfigured sanitization libraries
- Client-side heavy frameworks with unsafe rendering logic
The goal is to build intuition, not just exploitation skill.