Cross-Site Scripting (XSS) is a security flaw that allows attackers to insert malicious scripts into web pages read by other users. This sort of attack happens when a web application includes untrusted data on a web page without sufficient validation or escaping, allowing attackers to execute scripts within the victim's browser.

Types of XSS Attacks:

1.Stored XSS:

Malicious scripts are saved continuously on the target server, usually in a database. These scripts are then served to users whenever they visit a specific page, resulting in a long-term impact.

2.Reflected XSS :

The malicious script is inserted into a URL or other input, and the victim is duped into clicking the modified link. The script is then reflected from the web server and run within the victim's browser.

3.DOM-Based XSS:

The attack occurs within a web page's Document Object Model (DOM). Malicious scripts use the DOM to carry out harmful behaviors.

How XSS Works:

1.Injection:

An attacker introduces malicious code (often JavaScript) into a vulnerable website or web application.

2.User Interaction:

The victim interacts with the compromised web page, unwittingly triggering the execution of the injected script.

3.Exploitation:

The injected script runs on the victim's browser, gaining access to sensitive information including cookies, session tokens, and other user-specific data.

4.Consequences:

Attackers can steal user credentials, session tokens, or act on behalf of the victim, resulting in account hijacking, unlawful transactions, or the disclosure of sensitive information.

Prevention & Conservation:

1.Input Validation:

Validate and sanitize user input to ensure it is free of dangerous code.

2.Output Encoding:

To avoid the execution of inserted scripts, encode user-generated material before it is rendered on web pages.

3.HTTP Security Headers:

Use security headers like Content Security Policy (CSP) to limit which scripts can run on a website.

4.Use HTTPS:

Use secure communication channels to protect against Man-in-the-Middle attacks and data interception.

5.Web Application Firewalls (WAF):

Use WAFs to detect and prevent malicious requests based on established security policies.

Conclusion:

In the ever-changing universe of web security threats, XSS is a persistent and deadly flaw. Its abuse can have serious consequences, such as data breaches and a violation of user privacy. As web applications progress, the necessity of strong security measures cannot be stressed.