Today’s lesson goal: Learn about Cross Site Scripting (XSS) attacks, their mechanisms, impacts, and preventive measures.
Understanding Cross Site Scripting (XSS) Cross Site Scripting (XSS) is a type of security vulnerability typically found in web applications. XSS enables attackers to inject malicious scripts into web pages viewed by other users. These scripts can steal user data, deface websites, or redirect users to malicious sites.
Types of XSS Attacks
- Reflected XSS: The malicious script comes from the current HTTP request.
- Stored XSS: The script is stored on the target server, such as in a database, and is then reflected out to other users.
- DOM-based XSS: The vulnerability exists in the client-side code rather than the server-side code.
How XSS Works
- An attacker finds a way to get a victim to load web pages with insecure JavaScript scripts.
- These scripts run in the victim’s browser and can steal information, send requests on behalf of the victim, or perform other malicious actions.
Impact of XSS Attacks
- Data Theft: Stealing cookies, session tokens, or other sensitive information.
- Account Hijacking: Taking control of a user’s account on the affected website.
- Website Defacement: Altering the appearance of the website.
- Phishing: Displaying fake forms to capture user information.
Preventing XSS Attacks
- Input Sanitization: Ensuring that user input does not contain harmful scripts.
- Content Security Policy (CSP): Instructing the browser to only execute scripts from trusted sources.
- Encoding Data: Transforming special characters into HTML entities.
- Regular Security Audits: Checking for vulnerabilities in web applications.
Example of XSS Attack Suppose a website allows users to post comments without proper sanitization. An attacker could post a script as a comment, which other users’ browsers would execute, leading to potential data theft.
For a more in-depth understanding, watch this YouTube video: Understanding XSS Attacks
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