To prevent cross-site scripting (XSS) attacks using input validation and filtering, you can implement several strategies. First, validate all input data to ensure it meets expected formats and types. For example, if a field expects a numeric value, reject any non-numeric input.
Second, use input filtering to sanitize data by removing or encoding potentially harmful characters or scripts. For instance, convert special characters like "<" and ">" into their HTML entity equivalents, such as "<" and ">".
Additionally, employ a whitelist approach where only specific, approved characters and patterns are allowed. Any input that doesn't match the whitelist criteria is rejected.
For example, if a user is submitting a comment, you might allow letters, numbers, spaces, and basic punctuation but disallow script tags or JavaScript event handlers.
In the context of cloud services, platforms like Tencent Cloud offer Web Application Firewall (WAF) services that can help automate the process of input validation and filtering, providing an additional layer of security against XSS attacks.