How can I make login case sensitive login C#

Question

1.00/5 (2 votes)

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C#

f (string.IsNullOrEmpty(username_txt.Text) || string.IsNullOrEmpty(password_txt.Text))
            {
                MessageBox.Show("Please input Username and Password", "Error");
            }
            else
            {
                connection.Open();
                string selectQuery = "SELECT * FROM gamesuk.users WHERE username COLLATE utf8mb4_general_ci = '" + username_txt.Text + "' AND Password = '" + password_txt.Text + "';";

                command = new MySqlCommand(selectQuery, connection);
                mdr = command.ExecuteReader();
                if (mdr.Read())
                {
                    MySqlConnection connection = new MySqlConnection(MyConnection2);
                    string Query = "update gamesuk.users  set islogin='" + "1" + "' where username='" + this.username_txt.Text + "';";
                    MySqlCommand MyCommand2 = new MySqlCommand(Query, connection);
                    MySqlDataReader MyReader2;
                    connection.Open();
                    MyReader2 = MyCommand2.ExecuteReader();
                    while (MyReader2.Read())
                    {
                    }
                    connection.Close();
                    MessageBox.Show("Login Successful!");
                    Adminpanel.Visible = true;
                    // this.Hide();
                    //LoginSuccessForm frm2 = new LoginSuccessForm();
                    //frm2.ShowDialog();
                }
                else
                {
                    MessageBox.Show("Incorrect Login Information! Try again.");
                }
                connection.Close();

            }

Admin or admin as username or password

What I have tried:

i have tried using

COLLATE utf8mb4_general_ci

Posted 12-May-24 3:24am

lifeofguydonohue

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Comments

Richard MacCutchan 12-May-24 9:53am

You have two major security flaws in that code; you need to fix those first.

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OriginalGriff · Accepted Answer · 2024-05-12T05:25:00

Don't do it like that!

1) Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Always use Parameterized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'

The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'

Which SQL sees as three separate commands:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';

A perfectly valid SELECT

SQL

DROP TABLE MyTable;

A perfectly valid "delete the table" command

SQL

--'

And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?

2) Never store passwords in clear text - it is a major security risk. There is some information on how to do it here: Password Storage: How to do it.[^]

And remember: if you have any European Union users then GDPR applies and that means you need to handle passwords as sensitive data and store them in a safe and secure manner. Text is neither of those and the fines can be .... um ... outstanding. In December 2018 a German company received a relatively low fine of €20,000 for just that.

3) Look at surrounding all Command, Connection, and DataAdapter instances with using statements[^] - they are scarce resources and should be Disposed immediately you are finished with them.

Fix all of those first throughout your whole app, and then think about other problems. (Oh, and usernames probably shouldn't be case sensitive, and more than email addresses are!)