SQL Injection

SQL Injection (SQLi) is a web security vulnerability that allows an attacker to interfere with the queries that an application makes to its database. This can lead to unauthorized access to sensitive data, modification or deletion of data, and even complete control over the database.

Example of SQL Injection

Suppose you have a login form that takes a username and password - Programiz](https://www.programiz.com/sql/injection). The SQL query might look like this:

SELECT * FROM Users WHERE Username = 'user_input' AND Password = 'user_input'

An attacker could input:

' OR '1'='1

This would result in the query:

SELECT * FROM Users WHERE Username = '' OR '1'='1' AND Password = ''

Since '1'='1' is always true, the attacker bypasses the password check and gains access - Programiz](https://www.programiz.com/sql/injection).

Preventing SQL Injection with ADO.NET

ADO.NET is a data access technology in the .NET framework. To prevent SQL Injection, you should use parameterized queries. Here's an example:

using (SqlConnection connection = new SqlConnection(connectionString))
{
    SqlCommand command = new SqlCommand("SELECT * FROM Users WHERE Username = @username", connection);
    command.Parameters.AddWithValue("@username", username);
    connection.Open();
    SqlDataReader reader = command.ExecuteReader();
    // Process the data
}

Using parameterized queries ensures that user input is treated as data, not executable code.

Preventing SQL Injection with Dapper

Dapper is a micro-ORM that works with .NET and simplifies data access. It also supports parameterized queries to prevent SQL Injection. Here's an example:

var query = "SELECT * FROM Users WHERE Username = @username";
var parameters = new { username = "user_input" };
var results = await db.QueryAsync(query, parameters);

Dapper automatically handles parameter binding, making it safer against SQL Injection.

Preventing SQL Injection with EF Core

Entity Framework Core (EF Core) is an ORM that provides a higher-level abstraction for database operations. It uses LINQ to generate SQL queries, which inherently use parameterized queries. Here's an example:

var user = dbContext.Users.FirstOrDefault(u => u.Username == username);

EF Core ensures that user input is properly parameterized, preventing SQL Injection.

Summary

SQL Injection is a serious security vulnerability that can lead to unauthorized access and data breaches. To prevent it, always use parameterized queries, validate user input, and consider using ORMs like Dapper and EF Core that handle parameterization for you.