Stop SQL Injection in .NET

 The Problem: One Input Box Can Expose Your Entire Database

SQL Injection is still one of the top threats in .NET applications, especially when developers build SQL queries by string concatenation. Here’s a classic mistake:

string query = "SELECT * FROM Users WHERE Email = '" + email + "' AND Password = '" + password + "'";

If an attacker types this into the email field:

' OR 1=1 --

The query turns into:

SELECT * FROM Users WHERE Email = '' OR 1=1 --' AND Password = ''

Result: The attacker bypasses login or retrieves all users—a full data breach with one input.

 

✅ The Solution: Use Parameterized Queries with ADO.NET or Entity Framework

The safest and most effective solution in .NET is parameterized queries. They keep SQL logic and data separate, making injection impossible.

 

🔐 Example with ADO.NET:

using (SqlConnection conn = new SqlConnection(connectionString))

{

    SqlCommand cmd = new SqlCommand("SELECT * FROM Users WHERE Email = @email AND Password = @password", conn);

    cmd.Parameters.AddWithValue("@email", email);

    cmd.Parameters.AddWithValue("@password", password);

 

    conn.Open();

    SqlDataReader reader = cmd.ExecuteReader();

}

The attacker’s input is treated as a value, not code—so the query stays safe.

 

🌐 Example with Entity Framework (EF Core):

var user = dbContext.Users

    .FirstOrDefault(u => u.Email == email && u.Password == password);

EF automatically uses parameterized SQL behind the scenes, which protects against injection.

✅ Note: Always hash passwords—never store or query them as plain text!

 

🛡️ Why This Works

• Parameter values are never interpreted as SQL commands.
• Built-in escaping and type safety ensure nothing malicious sneaks through.
• Simple to implement, yet extremely effective.

 

🧠 Real-Life Example

A .NET developer for a healthcare web app used user inputs directly in SQL. One day, QA found a strange case where all patient data was visible just by tweaking the URL. The cause? SQL injection.

The fix was replacing all raw SQL with parameterized queries. After the change, penetration testing showed zero vulnerability, and the platform passed a security audit from a government agency.

 

🚀 Final Word

Don’t risk your reputation or your users' data.

Use parameterized queries with ADO.NET or Entity Framework. It’s the easiest, most reliable way to eliminate SQL injection risks in .NET applications—and it only takes a few lines of code.