How Can I Prevent SQL Injection in INSERT Statements with Textbox Comments?

SQL Injection Prevention on INSERT Statements with Textbox Comments

SQL injection vulnerabilities can arise in any SQL statement, including INSERT statements, if not handled properly.

In the context of an INSERT statement, an SQL injection attack can occur when an untrusted input, such as comments entered by users in a text box, is directly concatenated into the SQL query without proper sanitization or validation.

Example of an SQL Injection Attack

Consider a simplified comment table with two fields: an integer ID and a comment string. An INSERT statement to add a new comment might look like this:

INSERT INTO COMMENTS VALUES(122, 'I like this website');

However, if a malicious user enters the following comment:

'); DELETE FROM users; --

The SQL statement, without any processing, would become:

INSERT INTO COMMENTS VALUES(123, ''); DELETE FROM users; -- ');

This would result in the user not only adding a comment but also executing a malicious SQL command that deletes all records from the 'users' table.

Protection Against SQL Injection

To prevent SQL injection attacks, it's essential to use parameterized SQL statements. These statements use placeholders for untrusted input, and the database automatically handles the insertion of the input into the SQL query.

In .NET 2.0, you can use the SqlCommand class to execute parameterized SQL statements. For example, the following code would insert a comment using a parameterized SQL statement:

using (SqlConnection connection = new SqlConnection("connectionString"))
{
    connection.Open();

    using (SqlCommand command = new SqlCommand("INSERT INTO COMMENTS VALUES (@Id, @Comment)", connection))
    {
        command.Parameters.AddWithValue("@Id", 123);
        command.Parameters.AddWithValue("@Comment", comment);
        command.ExecuteNonQuery();
    }
}

By using parameterized SQL statements, you can effectively prevent SQL injection attacks by ensuring that malicious input is handled safely and doesn't affect the integrity of your database.

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