XSS- Cross Site Scripting vulnerability/ Cookie Stealing

introduction:

This vulnerability allows for an attacker's input to be sent to unsuspecting victims. The primary usage for this vulnerability is cookie stealing; if an attacker steals your cookie, they can log into whatever site they stole your cookie from under your account (usually, and assuming you were logged in at the time.)

what is cookie?

A cookie, also known as a web cookie, browser cookie, and HTTP cookie, is a piece of text stored on a user's computer by their web browser. A cookie can be used for authentication, storing site preferences, shopping cart contents, the identifier for a server-based session, or anything else that can be accomplished through storing text data.

Cookies may be set by the server with or without an expiration date. Cookies without an expiration date exist until the browser terminates, while cookies with an expiration date may be stored by the browser until the expiration date passes. Users may also manually delete cookies in order to save space or to address privacy issue .