Science Knowings: JavaScript Course For Social Media

Cross-Site Scripting (XSS)

Data Validation and Sanitization Recap

In our previous session, we covered data validation and sanitization techniques to prevent malicious input from breaking our applications. Now, let's dive into Cross-Site Scripting (XSS), a serious security vulnerability that can compromise user data and website integrity.

What is XSS?

Cross-Site Scripting (XSS)

XSS is a type of injection attack that allows attackers to execute malicious scripts on a victim's web browser. These scripts can steal sensitive information, redirect users to malicious websites, or even gain control over the victim's account.

How Does XSS Work?

XSS attacks exploit vulnerabilities in web applications that allow untrusted input to be included in dynamic web pages. These pages are then rendered in the victim's browser, where the attacker's malicious script can execute.

Types of XSS Attacks

Reflected XSS:

Injected script is reflected back to the victim in a request (e.g., as part of a URL or form submission).

Stored XSS:

Injected script is stored on the server and executed when vulnerable pages are loaded by victims.

DOM-Based XSS:

Injected script is inserted into the Document Object Model (DOM) of a web page and executed within the victim's browser.

Impact of XSS Attacks

  • Stealing sensitive information (e.g., credentials, cookies)
  • Redirecting users to malicious websites
  • Hijacking user sessions
  • Spreading malware
  • Defacing websites
  • Prevention Methods

    Input Validation and Escaping:

    Validate and escape user input to remove potentially malicious characters.

    Content Security Policy (CSP):

    Restrict the types of scripts that can be loaded and executed on a website.

    HttpOnly and Secure Flags:

    Prevent cookies from being accessed via JavaScript and only allow their transmission over secure connections.

    X-XSS-Protection Header

    Forces the browser to enable XSS protection features. It's an additional layer of defense, but not foolproof.

    Next Topic: Cross-Site Request Forgery (CSRF)

    In our next session, we'll discuss Cross-Site Request Forgery (CSRF), a different type of attack that exploits authentication mechanisms. Follow us to learn more and stay protected against common web vulnerabilities!