Tree's Notes
  • Overview
  • Tools & Cheatsheets
  • Hacking Methodology
  • Hands-on Practice
  • Linux
    • Linux Basics
  • Windows
    • Windows Basics
  • MacOS
    • MacOS Basics
  • Web
    • Web Basics
  • Mobile
    • iOS
    • Android
  • OS Agnostic
    • Template
  • Courses
    • Hack The Box
      • Bug Bounty Hunter
        • Module 1: Web Requests
        • Module 2: Introduction to Web Applications
        • Module 3: Using Web Proxies
        • Module 4: Information Gathering - Web Edition
        • Module 5: Attacking Web Applications with Ffuf
        • Module 6: JavaScript Deobfuscation
        • Module 7: Cross-Site Scripting (XSS)
        • Module 8: SQL Injection Fundamentals
        • Module 9: SQLMap Essentials
        • Module 10: Command Injections
        • Module 11: File Upload Attacks
        • Module 12: Server-Side Attacks
        • Module 13: Login Brute Forcing
        • Module 14: Broken Authentication
        • Module 15: Web Attacks
        • Module 16: File Inclusion
        • Module 17: Session Security
        • Module 18: Web Service & API Attacks
        • Module 19: Hacking Wordpress
        • Module 20: Bug Bounty Hunting Process
    • OffSec
      • 🦊EXP-301
        • Module 1: Windows User Mode Exploit Development: General Course Information
        • Module 2: WinDbg and x86 Architecture
        • Module 3: Exploiting Stack Overflows
        • Module 4: Exploiting SEH Overflows
        • Module 5: Introduction to IDA Pro
        • Module 6: Overcoming Space Restrictions: Egghunters
        • Module 7: Creating Custom Shellcode
        • Module 8: Reverse Engineering for Bugs
        • Module 9: Stack Overflows and DEP Bypass
        • Module 10: Stack Overflows and ASLR Bypass
        • Module 11: Format String Specifier Attack Part I
        • Module 12: Format String Specifier Attack Part II
        • Module 13: Trying Harder: The Labs
      • 🐙EXP-312
        • Module 1: macOS Control Bypasses: General Course Information
        • Module 2: Virtual Machine Setup Guide
        • Module 3: Introduction to macOS
        • Module 4: macOS Binary Analysis Tools
        • Module 5: The Art of Crafting Shellcodes
        • Module 6: The Art of Crafting Shellcodes (Apple Silicon Edition)
        • Module 7: Dylib Injection
        • Module 8: The Mach Microkernel
        • Module 9: XPC Attacks
        • Module 10: Function Hooking on macOS
        • Module 11: The macOS Sandbox
        • Module 12: Bypassing Transparency, Consent, and Control (Privacy)
        • Module 13: GateKeeper Internals
        • Module 14: Bypassing GateKeeper
        • Module 15: Symlink and Hardlink Attacks
        • Module 16: Injecting Code into Electron Applications
        • Module 17: Getting Kernel Code Execution
        • Module 18: Mach IPC Exploitation
        • Module 19: macOS Penetration Testing
        • Module 20: Chaining Exploits on macOS Ventura
        • Module 21: Mount(ain) of Bugs (archived)
      • ⚓IR-200
        • Module 1: Incident Response Overview
        • Module 2: Fundamentals of Incident Response
        • Module 3: Phases of Incident Response
        • Module 4: Incident Response Communication Plans
        • Module 5: Common Attack Techniques
        • Module 6: Incident Detection and Identification
        • Module 7: Initial Impact Assessment
        • Module 8: Digital Forensics for Incident Responders
        • Module 9: Incident Response Case Management
        • Module 10: Active Incident Containment
        • Module 11: Incident Eradication and Recovery
        • Module 12: Post-Mortem Reporting
        • Module 13: Incident Response Challenge Labs
      • 🐉PEN-103
      • 🐲PEN-200
        • Module 1: Copyright
        • Module 2: Penetration Testing with Kali Linux: General Course Information
        • Module 3: Introduction to Cybersecurity
        • Module 4: Effective Learning Strategies
        • Module 5: Report Writing for Penetration Testers
        • Module 6: Information Gathering
        • Module 7: Vulnerability Scanning
        • Module 8: Introduction to Web Application Attacks
        • Module 9: Common Web Application Attacks
        • Module 10: SQL Injection Attacks
        • Module 11: Client-side Attacks
        • Module 12: Locating Public Exploits
        • Module 13: Fixing Exploits
        • Module 14: Antivirus Evasion
        • Module 15: Password Attacks
        • Module 16: Windows Privilege Escalation
        • Module 17: Linux Privilege Escalation
        • Module 18: Port Redirection and SSH Tunneling
        • Module 19: Tunneling Through Deep Packet Inspection
        • Module 20: The Metasploit Framework
        • Module 21: Active Directory Introduction and Enumeration
        • Module 22: Attacking Active Directory Authentication
        • Module 23: Lateral Movement in Active Directory
        • Module 24: Enumerating AWS Cloud Infrastructure
        • Module 25: Attacking AWS Cloud Infrastructure
        • Module 26: Assembling the Pieces
        • Module 27: Trying Harder: The Challenge Labs
      • 🛜PEN-210
        • Module 1: IEEE 802.11
        • Module 2: Wireless Networks
        • Module 3: Wi-Fi Encryption
        • Module 4: Linux Wireless Tools, Drivers, and Stacks
        • Module 5: Wireshark Essentials
        • Module 6: Frames and Network Interaction
        • Module 7: Aircrack-ng Essentials
        • Module 8: Cracking Authentication Hashes
        • Module 9: Attacking WPS Networks
        • Module 10: Rogue Access Points
        • Module 11: Attacking Captive Portals
        • Module 12: Attacking WPA Enterprise
        • Module 13: bettercap Essentials
        • Module 14: Determining Chipsets and Drivers
        • Module 15: Kismet Essentials
        • Module 16: Manual Network Connections
      • 🔗PEN-300
        • Module 1: Evasion Techniques and Breaching Defenses: General Course Information
        • Module 2: Operating System and Programming Theory
        • Module 3: Client Side Code Execution With Office
        • Module 4: Phishing with Microsoft Office
        • Module 5: Client Side Code Execution With Windows Script Host
        • Module 6: Reflective PowerShell
        • Module 7: Process Injection and Migration
        • Module 8: Introduction to Antivirus Evasion
        • Module 9: Advanced Antivirus Evasion
        • Module 10: Application Whitelisting
        • Module 11: Bypassing Network Filters
        • Module 12: Linux Post-Exploitation
        • Module 13: Kiosk Breakouts
        • Module 14: Windows Credentials
        • Module 15: Windows Lateral Movement
        • Module 16: Linux Lateral Movement
        • Module 17: Microsoft SQL Attacks
        • Module 18: Active Directory Exploitation
        • Module 19: Attacking Active Directory
        • Module 20: Combining the Pieces
        • Module 21: Trying Harder: The Labs
      • ⚛️SEC-100
      • 🛡️SOC-200
        • Module 1: Introduction to SOC-200
        • Module 2: Attacker Methodology Introduction
        • Module 3: Windows Endpoint Introduction
        • Module 4: Windows Server Side Attacks
        • Module 5: Windows Client-Side Attacks
        • Module 6: Windows Privilege Escalation
        • Module 7: Windows Persistence
        • Module 8: Linux Endpoint Introduction
        • Module 9: Linux Server Side Attacks
        • Module 10: Linux Privilege Escalation
        • Module 11: Network Detections
        • Module 12: Antivirus Alerts and Evasion
        • Module 13: Active Directory Enumeration
        • Module 14: Network Evasion and Tunneling
        • Module 15: Windows Lateral Movement
        • Module 16: Active Directory Persistence
        • Module 17: SIEM Part One: Intro to ELK
        • Module 18: SIEM Part Two: Combining the Logs
        • Module 19: Trying Harder: The Labs
      • TH-200
        • Module 1: Threat Hunting Concepts and Practices
        • Module 2: Threat Actor Landscape Overview
        • Module 3: Communication and Reporting for Threat Hunters
        • Module 4: Hunting With Network Data
        • Module 5: Hunting on Endpoints
        • Module 6: Theat Hunting Without IoCs
        • Module 7: Threat Hunting Challenge Labs
      • 🦉WEB-200
        • Module 1: Introduction to WEB-200
        • Module 2: Tools (archived)
        • Module 3: Web Application Enumeration Methodology
        • Module 4: Introduction to Burp Suite
        • Module 5: Cross-Site Scripting Introduction and Discovery
        • Module 6: Cross-Site Scripting Exploitation and Case Study
        • Module 7: Cross-Origin Attacks
        • Module 8: Introduction to SQL
        • Module 9: SQL Injection
        • Module 10: Directory Traversal Attacks
        • Module 11: XML External Entities
        • Module 12: Server-side Template Injection - Discovery and Exploitation
        • Module 13: Command Injection
        • Module 14: Server-side Request Forgery
        • Module 15: Insecure Direct Object Referencing
        • Module 16: Assembling the Pieces: Web Application Assessment Breakdown
      • 🕷️WEB-300
        • Module 1: Introduction
        • Module 2: Tools & Methodologies
        • Module 3: ManageEngine Applications Manager AMUserResourcesSyncServlet SSQL Injection RCE
        • Module 4: DotNetNuke Cookie Deserialization RCE
        • Module 5: ERPNext Authentication Bypass and Remote Code Execution
        • Module 6: openCRX Authentication Bypass and Remote Code Execution
        • Module 7: openITCOCKPIT XSS and OS Command Injection - Blackbox
        • Module 8: Concord Authentication Bypass to RCE
        • Module 9: Server-Side Request Forgery
        • Module 10: Guacamole Lite Prototype Pollution
        • Module 11: Dolibarr Eval Filter Bypass RCE
        • Module 12: RudderStack SQLi and Coraza WAF Bypass
        • Module 13: Conclusion
        • Module 14: ATutor Authentication Bypass and RCE (archived)
        • Module 15: ATutor LMS Type Juggling Vulnerability (archived)
        • Module 16: Atmail Mail Server Appliance: from XSS to RCE (archived)
        • Module 17: Bassmaster NodeJS Arbitrary JavaScript Injection Vulnerability (archived)
    • SANS
      • FOR572
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On this page
  • Introduction to the Sandbox
  • Accessing the Sandbox
  • Understanding the Sandbox
  • JavaScript Basics for Offensive Uses
  • Syntax Overview
  • Useful APIs
  • Cross-Site Scripting - Discovery
  • Reflected Server XSS
  • Stored Server XSS
  • Reflected Client XSS
  • Stored Client XSS
Edit on GitHub
  1. Courses
  2. OffSec
  3. WEB-200

Module 5: Cross-Site Scripting Introduction and Discovery

Introduction to the Sandbox

Accessing the Sandbox

Start the VPN and start the VM. Add the IP to hosts file.

Understanding the Sandbox

Explaining the sandbox webpage.

JavaScript Basics for Offensive Uses

Syntax Overview

Function example

01  function processData(data) {
02    data.items.forEach(item => {
03      console.log(item)
04    });
05  }
06
07  let foo = {
08    items: [
09      "Hello",
10      "Zdravo",
11      "Hola"
12    ]
13  }
14
15  processData(foo)

Useful APIs

Starting HTTP listener

kali@kali:~$ python3 -m http.server 80
Serving HTTP on 0.0.0.0 port 80 (http://0.0.0.0:80/) ...

HTTP Server Log

kali@kali:~$ python3 -m http.server 80
Serving HTTP on 0.0.0.0 port 80 (http://0.0.0.0:80/) ...
172.16.174.4 - - [11/Aug/2021 19:15:53] "GET /hello HTTP/1.1" 404 -

Original Keylogging Payload

function logKey(event){
	console.log(event.key)
}

document.addEventListener('keydown', logKey);

HTTP Server Log

...
192.168.121.101 - - [11/Aug/2021 19:23:39] "GET /k?key=I HTTP/1.1" 404 -
192.168.121.101 - - [11/Aug/2021 19:23:39] code 404, message File not found
192.168.121.101 - - [11/Aug/2021 19:23:39] "GET /k?key= HTTP/1.1" 404 -
192.168.121.101 - - [11/Aug/2021 19:23:39] code 404, message File not found
192.168.121.101 - - [11/Aug/2021 19:23:39] "GET /k?key=l HTTP/1.1" 404 -
192.168.121.101 - - [11/Aug/2021 19:23:40] code 404, message File not found
192.168.121.101 - - [11/Aug/2021 19:23:40] "GET /k?key=i HTTP/1.1" 404 -
192.168.121.101 - - [11/Aug/2021 19:23:40] code 404, message File not found
192.168.121.101 - - [11/Aug/2021 19:23:40] "GET /k?key=k HTTP/1.1" 404 -
192.168.121.101 - - [11/Aug/2021 19:23:40] code 404, message File not found
192.168.121.101 - - [11/Aug/2021 19:23:40] "GET /k?key=e HTTP/1.1" 404 -
...

Cross-Site Scripting - Discovery

Reflected Server XSS

Often found in locations where user input is sent via GET parameters.

It's inside a <div> tag, it may be vulnerable. Testing with HTML injection has less potential for error — this doesn't always mean we can inject JavaScript but is a great indicator.

Encoded search payload

search.php?s=%3Cscript%3Ealert(0)%3C/script%3E

Stored Server XSS

Reflected Client XSS

Mozilla's innerHTML Bypass

const name = "<img src='x' onerror='alert(1)'>";
el.innerHTML = name; // shows the alert

Stored Client XSS

PreviousModule 4: Introduction to Burp SuiteNextModule 6: Cross-Site Scripting Exploitation and Case Study

Last updated 6 months ago

🦉
Logging inputs
logKey function
Capturing Key stroke
Typing into Eval
Using fetch
Sending keystrokes back
Searchin for "offsec"
Inspecting "offsec"
Injecting HTML to Search
Search Alert box
XSS rendered on Victim - Search
Reviewing HTTP Response in Burp Suite
Leaving a comment
Blog Comment Inspection
Sanitized Comment
Inspecting Sanitized Comment
Raw HTML of Comment
H1 in Username
Rendered H1
XSS payload in Blog Comment
Executing XSS Payload using Target User Browser
Survey Home Page
Survey HTML Injection
Finding Request in the Network Tools
Viewing the Response Payload
Reviewing Survey.js
Payload not executing in Client XSS
Reviewing Injection Point
Exploiting with Mozilla's Bypass
Summary of Answers
HTML in Survey
Rendered HTML in Survey
XSS Payload in Survey
Alert Box on Result Page
Alert Box in Victim's Browser