10 Questions
What is the purpose of the JavaScript function btoa()?
To encode a string of binary data to create a base64-encoded ASCII string
What type of XSS attack involves embedding a malicious script within user-controlled input reflected to the user?
Reflected XSS
What can be used to experiment with displaying values, such as cookies, in a web browser?
alert() function
What is the least common type of XSS attack?
DOM-based XSS
What is the reverse function of btoa()?
atob()
What is the primary function of the Same-Origin Policy (SOP) in modern web browsers?
To prevent a malicious script on one web page from obtaining access to sensitive data on another page
Why is it essential to test XSS exploits on a browser similar to the target's browser?
Because different browsers process certain code snippets differently
What is the purpose of the alert() function in JavaScript?
To display a JavaScript alert in a web browser
What is the shortcut to open the Console in Google Chrome?
Ctrl + Shift + J
What is the primary characteristic of an XSS attack?
It's a client-side attack that takes place on the target's web browser
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
Understand how XSS vulnerabilities allow malicious scripts to bypass the Same-Origin Policy and access sensitive data on web pages.
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