Importance of Input Validation for Web-Based Client-Server Applications

C.

When designing a web-based client-server application with a single application server and a database cluster backend, input validation should be performed on the application server.

Input validation is a critical security measure that ensures that user input is safe and trustworthy before it is processed by the application. Input validation can help prevent a range of security vulnerabilities, including injection attacks, buffer overflows, and cross-site scripting (XSS) attacks.

Performing input validation on the client side can be problematic because client-side code can be easily manipulated or bypassed by an attacker. This is particularly true for web applications, which are vulnerable to attacks such as client-side injection attacks and XSS attacks.

Using database stored procedures for input validation is also not recommended. While stored procedures can provide some level of protection against SQL injection attacks, they are not foolproof, and they can be difficult to implement and maintain. Additionally, stored procedures can be vulnerable to other types of attacks, such as buffer overflows and privilege escalation attacks.

Performing input validation on the application server is the best practice because it allows for centralized control and enforcement of input validation rules. This approach also makes it easier to maintain and update the input validation code, as it is only necessary to make changes in one location. Additionally, input validation on the application server can be augmented with other security measures, such as rate limiting, to help prevent denial of service attacks.

Using HTTPS is not an appropriate answer to this question as it is a protocol for secure communication over the internet and does not directly address the issue of input validation. However, it is still an important security measure to use to protect data in transit between the client and the server.