How can I test my PHP MySQL injection example?

Question

I want to use PHP/Mysql injection with a login example, my code is below.

I have tried with a username of anything' -- and an empty password but it doesn't work and I couldn't log in.

Could anyone help me?

<?php
mysql_connect('localhost','root','root');
mysql_select_db('hp');
?>

<form action="" method="post">
<table width="50%">
    <tr>
        <td>User</td>
        <td><input type="text" name="user"></td>
    </tr>
    <tr>
        <td></td>
        <td><input type="text" name="password"></td>
    </tr>
</table>
    <input type="submit" value="OK" name="s">
</form>

<?php
if($_POST['s']){
    $user = $_POST['user'];
    $pass = $_POST['password'];     
    $re = mysql_query("select * from zend_adminlist where user_name = '$user' and password = '$pass'");

    if(mysql_num_rows($re) == 0){       
        echo '0';
    }else{
        echo '1';
    }
}
?>

Answer 1

One of the most common examples is this query:

' or '1'='1

If you enter this as the username and password into some unsanitized login input the query changes like so:

Original: SELECT * FROM USERS WHERE USER='' AND PASS='';
Modified: SELECT * FROM USERS WHERE USER='' or '1'='1' AND PASS='' or '1'='1';

This causes each thing its looking for to be true, as 1 will always equal 1. Problem with this method is it does not allow the selection of a particular user. Doing so you need to make it ignore the AND statement by commenting it out as seen in other examples.