Explain the XSS attack. How to prevent it?

Cross-site scripting, commonly known as an XSS attack, allows an attacker to impersonate a target user and do activities that the user is capable of, allowing the attacker to steal any of the user’s data. An attacker who can impersonate a privileged victim user can acquire complete control of the application’s data and capabilities. In this attack, the attacker injects malicious client-side code into web services in order to steal data, run harmful code, take control of a user’s session, and perform a phishing scam.

The following are some strategies to avoid an XSS attack:

  1. Cross-check user’s input
  2. Sanitize HTML
  3. Employ anti-XSS tools
  4. Use encoding
  5. Check for regular updates of the software