Cross-Site Scripting (XSS) allows attackers to inject malicious scripts into web pages viewed by other users, potentially stealing credentials and hijacking sessions.
What is XSS?
XSS attacks occur when an application includes untrusted data in a web page without proper validation or escaping.
XSS Attack Types
Stored XSS
Malicious script is permanently stored on the target server and served to users.
Reflected XSS
Script is reflected off a web server via URLs, error messages, or search results.
DOM-based XSS
Vulnerability exists in client-side code rather than server-side.
Prevention Strategies
- Output Encoding - Encode data when rendering in HTML, JavaScript, CSS, or URLs.
- Content Security Policy - Implement CSP headers to restrict script sources.
- HTTPOnly Cookies - Prevent JavaScript access to sensitive cookies.
Conclusion
XSS remains a prevalent web vulnerability. By implementing proper output encoding, Content Security Policy headers, and secure cookie practices, you can effectively protect your users from XSS attacks.