Cross—site scripting (XSS) is a type of website security vulnerability that allows an attacker to inject malicious code that will be executed by the browser of an unsuspecting site visitor. This can lead to the theft of sensitive information, such as login credentials or other personal data.
XSS attacks usually occur when a website allows you to enter invalid data on a web page, for example, through a search bar or a comment form. This data is then stored on the server, and when another user visits the page, malicious code is executed in his browser.
There are two main types of XSS: stored and reflected:
- stored XSS occurs when malicious code is stored on the server and executed every time the page is loaded;
- reflected XSS occurs when malicious code is sent to the server, processed, and immediately returned to the user’s browser without saving.
To prevent XSS attacks, it is important to check and disinfect any user input before displaying it on a web page. This can be done using server-side validation, client-side validation, or a combination of the two. In addition, it is important to encode any user input before displaying it on the page so that special characters are not interpreted by the browser as code.
XSS is a serious security threat that can lead to the theft of confidential information from the site. To prevent XSS attacks, it is important to check the data entered by the user, as well as encode it before displaying it on the page. By taking these precautions, site owners can ensure the safety of their users.