Cross-site scripting attack, XSS is a common web security vulnerability in which an attacker injects malicious script code into a trusted website, causing the browser to execute the malicious code on the user's end. This attack exploits a website's improper handling of user input data to embed malicious scripting code into a web page, thereby stealing sensitive user information, hijacking user sessions, modifying web page content, etc.
XSS attacks are usually divided into three types:
Stored XSS: The attacker stores the malicious script code in the database or file of the website, and when other users visit the page, the malicious script will be dynamically loaded and executed.
Reflex XSS: The attacker passes the malicious script code to the target user through URL parameters, etc. When the user clicks on the link containing the malicious script, the script is parsed and executed by the web page.
DOM-type XSS: The attacker takes advantage of the way the browser parses HTML documents to execute malicious script code by modifying the DOM structure of the page.
Methods to prevent XSS attacks include:
Input validation and filtering: Strict validation and filtering of user input data to prevent the injection of malicious scripting code. Input data can be filtered and cleaned using techniques such as regular expressions and whitelist filtering.
Output escaping: When rendering user input data into web pages, special characters are escaped and converted to their corresponding HTML entities, thus preventing the execution of malicious scripts.
HTTP header settings: By setting appropriate HTTP response headers, such as Content-Security-Policy (CSP) and X-XSS-Protection, you can increase the browser's protection against malicious scripts.
Use secure encoding functions: Use secure encoding functions, such as the automatic escaping provided by the html/template package in Golang, to ensure that the output is automatically escaped during rendering.
Secure session management: Use secure session management mechanisms, including appropriate cookie settings, session tokens and session expiration mechanisms, to prevent hijacking and abuse.
Regular updates and maintenance: Regularly update and maintain the application and related software libraries to patch known security vulnerabilities in a timely manner.
In summary, preventing XSS attacks requires a combination of input validation, output escaping, HTTP header settings, secure encoding functions, and other aspects to ensure that applications handle user input data appropriately and avoid injection and execution of malicious scripts.