Php log in allows entry with no user/pass - php

Question

Hey guys ive put together a basic user log in for a secure admin area and it seems to work great, if you enter a correct user/pass you get access, if you enter the wrong user pass, you get no access. However if you enter nothing in both fields you get access.
This is how it works.
Creating a user, a basic form POSTS to this php file.
<?php
$con = mysqli_connect(credentials are all good) or die(mysqli_error($con)) ;
$escapedUser = mysqli_real_escape_string($con, $_POST['user']);
$escapedPass = mysqli_real_escape_string($con, $_POST['pass']);
$some_str = md5(uniqid(mt_rand(), true));
$base_64str = base64_encode($some_str);
$modified_base64 = str_replace('+', '.', $base_64str);
$gensalt = substr($modified_base64, 0, 22);
$format_str = "$2y$10$"; // 2y for Blowfish and 10 times.
$salt = $format_str . $gensalt . "$";
$hashed_pass = crypt($escapedPass, $salt);
$query = "INSERT INTO `userpass` (`username`, `password`, `salt`) VALUES ('$escapedUser', '$hashed_pass', '$salt'); ";
if(isset($escapedUser) && isset($hashed_pass))
{
mysqli_query($con, $query);
header("Location: ausers.php");
exit();
}
Echo "Something went wrong!";
?>
The database appears to be storing these fine
We then log in with this code
<?php
$con = mysqli_connect(again credentials are fine) or die(mysqli_error($con)) ;
$escapedUser = mysqli_real_escape_string($con, $_POST['user']);
$escapedPass = mysqli_real_escape_string($con, $_POST['pass']);
$saltQuery = "select salt from userpass where username = '$escapedUser';";
$result = mysqli_query($con, $saltQuery);
$row = mysqli_fetch_assoc($result);
$salt = $row['salt'];
$hashed_pass = crypt($escapedPass, $salt);
if(isset($escapedUser) && isset($hashed_pass))
{
$userQuery = "SELECT * FROM userpass WHERE username='$escapedUser' AND password='$hashed_pass'";
$userpass = mysqli_query($con, $userQuery);
$count = mysqli_num_rows($userpass);
if($count == 1)
{
$_SESSION['username'] = $escapedUser;
header("location: aindex.php");
exit();
}
header("Location: alogin.htm");
exit();
}
Echo "Something went wrong!";
?>
So as i said, this seems to work fine for when any user pass combination is given whether access granted or denied however using no user and pass and pressing log in allows entry. Any ideas? THeres no blank rows in the database table.
Side question, is this salt/hash method correct, its my first attempt.

Answer 1

For your login code, your condition relies on an isset() test. You perform this test on $escapedUser and $hashed_pass. Both of these variables were actually assigned values earlier in the code! Once you assign a value to the variable, it will pass the isset() test, even if the value is an empty string. You might want to use an empty() check, perhaps on the original $_POST variables.
Moving on to the inner condition, which tests if the mysql query returns exactly 1 row of results. If there were truly no rows with empty values, then this condition would never pass because the query would return 0 rows. But it is passing. Two things to consider:
Notice that your registering code uses the same isset() test. Therefore it is very possible that someone used your registration form, submitted empty fields, and successfully registered a row with empty user and password fields. Have you explicitly queried your database for empty fields and actually come up with 0 results?
Your query uses SELECT *. Perhaps this is causing the query to return some sort of aggregate value (like a COUNT() or something that always has a result no matter what). Perhaps try explicitly defining the columns to return?
I cannot comment on your salt/hash method as I have no experience in that part. Hope you find this helpful!

Answer 2

In my opinion you need more than one level of checks in any form, whether it be registration, comments, login, etc. The way I prefer to go about it is a tiered approach. It may work better for you, but it's just an example.
By doing it this way, you ensure that your input will never be empty. Another issue I see with your login script is that you never compare the input with the database so how can you know if they entered the correct information? The only thing allowing them to login is that the query returned a record. This is also why they can login with a blank form.
<?php
$con = mysqli_connect(again credentials are fine) or die(mysqli_error($con)) ;
/* Ensures that form was submitted before any processing is done */
if (isset($_POST)) {
$User = $_POST['user']);
$Pass = $_POST['pass']);
if (!empty($User)) {
if (!empty($Pass)) {
$escapedUser = mysqli_real_escape_string($con, $User);
$escapedPass = mysqli_real_escape_string($con, $Pass);
/* you need to verify the password here, before adding the salt */
$saltQuery = "select salt from userpass where username = '$escapedUser'";
$result = mysqli_query($con, $saltQuery);
$row = mysqli_fetch_assoc($result);
$salt = $row['salt'];
$hashed_pass = crypt($escapedPass, $salt);
$userQuery = "SELECT * FROM userpass WHERE username='$escapedUser' AND password='$hashed_pass'";
/* you need to verify the username somewhere here */
$userpass = mysqli_query($con, $userQuery);
$count = mysqli_num_rows($userpass);
if($count == 1)
{
$_SESSION['username'] = $escapedUser;
header("location: aindex.php");
exit();
} else {
header("Location: alogin.htm");
exit();
}
} else {
echo "Please enter a password.";
}
} else {
echo "Please enter a username.";
}
} else {
echo "You have not entered any information.";
}
?>