Understanding cross-site scripting (XSS) attacks

Cross-site scripting (XSS) is a type of security attack where an attacker injects malicious scripts into trusted websites. These attacks can compromise user interactions with the website, steal sensitive data, and spread malware. There are three main types of XSS attacks: reflected, stored, and DOM-based. Reflected XSS involves tricking users into clicking a link containing the payload, while stored XSS injects the script directly into the website's database. DOM-based XSS occurs within the victim's browser by manipulating the Document Object Model (DOM). To prevent XSS attacks, developers should validate and sanitize user input, use trusted libraries for input sanitization, employ modern web frameworks, use safe HTML attributes, implement output encoding, utilize Content Security Policy, set HttpOnly and Secure attributes on cookies, use appropriate response headers, and conduct penetration testing.