Web Security: XSS and Same-Origin Policy
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Questions and Answers

What is the purpose of the JavaScript function btoa()?

  • To decode a base64-encoded ASCII string
  • To encode a string of binary data to create a base64-encoded ASCII string (correct)
  • To display a number or a text string in the console log
  • To remove white space and special characters from a string

    • What type of XSS attack involves embedding a malicious script within user-controlled input reflected to the user?

  • DOM-based XSS
  • Stored XSS
  • Reflected XSS (correct)
  • Cross-site Scripting

    • What can be used to experiment with displaying values, such as cookies, in a web browser?

  • alert() function (correct)
  • atob() function
  • btoa() function
  • console.log() function

    • What is the least common type of XSS attack?

    <p>DOM-based XSS</p> Signup and view all the answers

    What is the reverse function of btoa()?

    <p>atob()</p> Signup and view all the answers

    What is the primary function of the Same-Origin Policy (SOP) in modern web browsers?

    <p>To prevent a malicious script on one web page from obtaining access to sensitive data on another page</p> Signup and view all the answers

    Why is it essential to test XSS exploits on a browser similar to the target's browser?

    <p>Because different browsers process certain code snippets differently</p> Signup and view all the answers

    What is the purpose of the alert() function in JavaScript?

    <p>To display a JavaScript alert in a web browser</p> Signup and view all the answers

    What is the shortcut to open the Console in Google Chrome?

    <p>Ctrl + Shift + J</p> Signup and view all the answers

    What is the primary characteristic of an XSS attack?

    <p>It's a client-side attack that takes place on the target's web browser</p> Signup and view all the answers

    Study Notes

    XSS Vulnerability

    • XSS allows an attacker to inject malicious scripts into a web page viewed by another user, bypassing the Same-Origin Policy (SOP)
    • SOP is a security mechanism implemented in modern web browsers to prevent a malicious script on one web page from obtaining access to sensitive data on another page
    • SOP defines origin based on the protocol, hostname, and port

    JavaScript for XSS

    • Basic knowledge of JavaScript is crucial for understanding XSS exploits and adapting them to your needs
    • XSS is a client-side attack that takes place on the target's web browser
    • Different browsers process certain code snippets differently, making it essential to test attacks on a browser similar to the target's

    JavaScript Console and Essential Functions

    • The Console tab can be accessed in:
      • Firefox: Ctrl + Shift + K
      • Google Chrome: Ctrl + Shift + J
      • Safari: Command + Option + J
    • Essential JavaScript functions:
      • Alert: displays a JavaScript alert in a web browser (e.g., alert(1) or alert('XSS'))
      • Console log: displays a value in the browser's JavaScript console using console.log() (e.g., console.log(1) or console.log("test text"))
      • Encoding: btoa("string") encodes a string of binary data to create a base64-encoded ASCII string, and atob("base64_string") is the reverse function

    Types of XSS

    • There are three main types of XSS:
      • Reflected XSS: relies on user-controlled input reflected to the user
      • Stored XSS: relies on user input stored in the website's database
      • DOM-based XSS: exploits vulnerabilities within the Document Object Model (DOM) to manipulate existing page elements without needing to be reflected or stored on the server

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    Quiz Team

    Description

    Understand how XSS vulnerabilities allow malicious scripts to bypass the Same-Origin Policy and access sensitive data on web pages.

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