Cross-site scripting (XSS) is a type of computer security vulnerability typically found in web applications. It allows an attacker to inject malicious code, usually in the form of a client-side script, into the web pages viewed by other users. XSS attacks are an attack technique used by hackers to manipulate web clients and steal data or modify the functionality of a website.
XSS attacks are typically performed by injecting malicious scripts into web pages by exploiting vulnerabilities in the web application. The malicious code can be written in any language that is supported by the client-side browser such as HTML, JavaScript, ActionScript, and VBScript. Once the malicious code is injected, it is executed when the affected page is visited by the user. The malicious code can be used for a number of purposes ranging from redirecting users to malicious websites, stealing sensitive information, altering the website’s behavior, and running unauthorized commands.
A large number of modern websites employ various techniques such as input validation to prevent XSS attacks. Input validation refers to the practice of checking user input before passing it to the web server. This technique helps to ensure that only valid data is sent to the server and that any potential malicious code is discarded. Additionally, modern web browsers also employ a mechanism called “Content Security Policy” to help protect users from XSS attacks.
Despite the various techniques employed to mitigate XSS attacks, they remain one of the most dangerous of web security threats. As such, web developers should take extra care when designing and implementing web applications, as any vulnerability in the application can be exploited by malicious actors.
