Secure Coding Tutorials

Secure Coding Best Practices

This tutorial series covers essential principles and practical techniques for writing secure code across various Microsoft development platforms. Protecting your applications and user data from vulnerabilities is paramount.

Introduction to Secure Coding

Understand the landscape of software security, common threats, and the importance of a secure-by-design approach. Learn about the OWASP Top 10 and how to mitigate common web vulnerabilities.

Key concepts:

Threat Modeling
Principle of Least Privilege
Defense in Depth

Input Validation and Sanitization

Improperly handled user input is a primary source of security vulnerabilities. This section focuses on techniques to validate and sanitize all external inputs to prevent injection attacks (SQL, XSS, Command Injection).

Example of strict validation:


                        function isValidEmail(email) {
                            const emailRegex = /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/;
                            return emailRegex.test(email);
                        }

Always use parameterized queries for database interactions:


                        // C# Example using ADO.NET
                        string sql = "SELECT * FROM Users WHERE Username = @username AND Password = @password";
                        SqlCommand command = new SqlCommand(sql, connection);
                        command.Parameters.AddWithValue("@username", username);
                        command.Parameters.AddWithValue("@password", password);
                        // ... execute command

Authentication and Authorization

Implementing robust authentication (verifying who the user is) and authorization (determining what the user can do) is crucial for application security.

Learn about:

Password Hashing (e.g., using BCrypt or Argon2)
Multi-Factor Authentication (MFA)
Role-Based Access Control (RBAC)
Secure Session Management

Avoid storing plain-text passwords. Use strong, salted hashing algorithms.

Cryptography Basics

Understand when and how to use encryption for data at rest and in transit. This includes concepts like symmetric vs. asymmetric encryption and digital signatures.

Secure communication using TLS/SSL is essential for web applications.

When handling sensitive data, consider using built-in .NET cryptography classes:


                        // C# Example for AES Encryption
                        using (Aes aes = Aes.Create())
                        {
                            aes.Key = GenerateKey(); // Implement proper key generation
                            aes.IV = GenerateIV();   // Implement proper IV generation

                            // ... encrypt data ...
                        }

Secure Error Handling and Logging

Avoid revealing sensitive system information in error messages. Implement comprehensive logging to track security-relevant events.

Good logging practices include:

Logging failed login attempts.
Logging authorization failures.
Logging significant data modifications.
Using structured logging for easier analysis.

Log sensitive data only when absolutely necessary and with appropriate controls.

Further Resources

Explore these links for more in-depth information and tools: