A Cross-Site Scripting (XSS) is an attack where an attacker injects malicious scripts (usually JavaScript) into a web page viewed by other users. This malicious script runs in the unsuspecting user’s browser, potentially stealing sensitive information such as session cookies, login credentials, or personal details. XSS exploits a web application’s failure to properly validate and sanitize users’ inputs, making it a common vulnerability in web applications.
Example:
An attacker posts a malicious JavaScript code in a comment section of a forum. When other users visit the page and view the comment, the code executes in their browsers, capturing their session cookies. The bad actor can then use these cookies to impersonate the users and perform actions on their behalf, such as changing account settings or accessing private information.