This really belongs on codereview.stackexchange.com, but I'll give it a shot anyway.

Firstly, I'd add a csrf token to your form to stop those types of attacks.

//the most simple type of csrf token

if (!isset($_SESSION['token'])):

    $token = md5(uniqid(rand(), TRUE));

    $_SESSION['token'] = $token;

else:

    $token = $_SESSION['token'];

endif;

Then in your form, include a hidden input field:

<input type=hidden name=token id=token value=<?php echo $token; ?>/>

Then in your ajax, add the token.

var usrnm = $('#usrnm').val();

var pswdlogin = $('#pswdlogin').val();

var token = $('#token').val();



{

    usrnm: usrnm,

    pswdlogin: pswdlogin,

    token: token

}

Then in your php, let's stop the undefined index errors on access of that page directly.

$usrnm_original = isset($_POST['usrnm'])?$_POST['usrnm']:false;

$pswdlogin_original = isset($_POST['pswdlogin'])?$_POST['pswdlogin']:false;

$token = isset($_POST['token'])$_POST['token']:false;

Then we need to check if the token that was passed is the same as our token

if(!$_SESSION['token'] == $token):

    die('CSRF Attacks are not allowed.');

endif;

Then we need to stop using mysqli_query when accepting user data, even if sanitizing with mysqli_real_escape_string and instead use prepared statements. Also, procedural style code makes me cry, so we'll be changing that. Furthermore, let's return an array with a status and a message, so it's easier to handle the error and success reporting.

$ret = array();

$mysqli = new mysqli(localhost, cSDEqLj, 4GFU7vT, dbname);



if($sql = $mysqli->prepare('SELECT * FROM registration WHERE email = ? and password = ?')):

    $sql->bind_param('ss', $usrnm_original, $pswd_original);



    if($sql->execute()):



        $sql->fetch();



        if($sql->num_rows > 0):

            $ret['status'] = true;

            $ret['msg'] = 'You have successfully logged in! Redirecting you now';

        else:

            $ret['status'] = false;

            $ret['msg'] = 'The credentials supplied were incorrect. Please try again';

        endif;

    endif;

    $sql->close();

    return json_encode($ret);

endif;

Now we need to modify your post function.

$.post(http://xyz/mobile/php/logmein.php,

{

  usrnm: usrnm,

  pswdlogin: pswdlogin,

  token:token

},

function(data) {



  if (data.status == true) {



    window.open(http://xyz/mobile/home.html?email= + usrnm + , _parent);



  } else {

    alert(data.msg);

    $('#loginstatus').text(data.msg);

  }

}, 'json');

Finally, and most importantly, you have a plain text method of passwords being used, which makes no sense from a security perspective. This is precisely how you get hacked. Instead, you should be using at least the sha256 hashing method. Change how the passwords are stored in the database to use sha256 then make a comparison by passing that into the SQL selector, example:

$pswdlogin_original = isset($_POST['pswdlogin'])? hash('sha256', $_POST['pswdlogin']):false;

And when saved in the database, the password will look like fcec91509759ad995c2cd14bcb26b2720993faf61c29d379b270d442d92290eb for instance.

My answer has been for clarity sake, but in reality, you shouldn't even be reinventing things. There's plenty of applications and framework's out there that have placed countless hours into securing their authentication systems. I would recommend having a look into all of these, as they'll help build your core programming skills and teach fundamental OOP practices

• Lararvel 4.x


• Zend 2


• Phalcon


• Yi

Hopefully this has been helpful.