6. Flawed Validation Rules

Flawed validation rules in IT web applications can lead to security vulnerabilities, incorrect data processing, and poor user experience. Here’s how you can handle them effectively:

1. Understand the Flaws

- Identify whether the validation issue is syntactic (format-related) or semantic (business logic-related).

- Check if the validation relies too much on client-side controls, which attackers can bypass.

2. Implement Robust Input Validation

- Use allow listing (permitting only expected values) instead of deny listing (blocking known bad values).

- Validate input at multiple layers—client-side for user experience, but always enforce validation on the server-side.

- Apply strict data type validation (e.g., integer parsing with exception handling).

3. Prevent Business Logic Vulnerabilities

- Avoid assumptions about user behaviour—users may interact with the application in unexpected ways.

- Ensure validation rules align with business requirements (e.g., preventing users from ordering more items than available stock).

4. Secure Against Common Attacks

- Protect against SQL Injection and Cross-Site Scripting (XSS) by validating and sanitizing input.

- Use JSON Schema or XML Schema for structured data validation.

5. Regularly Test and Update Validation Rules

- Conduct penetration testing to identify flaws in validation logic.

- Keep validation rules updated to adapt to evolving security threats.