Within
the global media there are instances of websites and data bases being
compromised all the time. Keeping sensitive data secure is essential for
developers especially if they have a user database, it could be
compromised and user’s sensitive data accessed.Here at Codingsec we will
now show you how to create a secure login for your website and also how
to protect your website against common hacks used frequently today:
In this example you will require PHP 5.3 or later and also MySQL version 4.1.3
or later, you will also need a web server that is configured to use PHP
and MySQL. This can be on your own server or one from a web hosting
company.Configure serverThe large majority of web
hosting companies will already have PHP and MySQL installed and
configured. However it is essential to check that the hosting service
that you are using has the required versions installed. Keeping both PHP
and MySQL software up to date on your server is essential for
security.To check the version of PHP and mySQL on your server use the phpinfo();
function.If you have your own server then you should install the
required software, installing an XAMPP stack is highly recommended.
Below you will find the download link so you cans select the right one
for the operating system that you are using.
http://www.apachefriends.org/en/xampp.html
If you are using your server for production purposes then using this method is not recommended.
To configure your server when using Linux download the required packages, for example within Ubuntu:
sudo apt-get install lamp-server^ phpmyadmin
After installing the required components ensure that you secure MySQL with a secure password.
Configure MySQL Database
Log in to your configured server with your Admin/root account.
Now you should create a database named “secure_login”.
You can see how to do this when using Phpmyadmin.
SQL Code:
CREATE DATABASE `secure_login`;
CREATE DATABASE `secure_login`;
Within some hosting areas, doing this within Phpmyadmin is not available so you will need to do this through cPanel.
Create User with SELECT, UPDATE and INSERT privileges.
To add new users you will need to have full Admin privileges (root).
SQL Code:
CREATE USER ‘sec_user’@’localhost’ IDENTIFIED BY ‘eKcGZr59zAa2BEWU';
GRANT SELECT, INSERT, UPDATE ON `secure_login`.* TO ‘sec_user’@’localhost';
Here are the details of the User that is created using this code:
User: “sec_user”
Password: “eKcGZr59zAa2BEWU”
It is an excellent idea to create a user with a limited amount of
privileges so in the worst case scenario of a security breach the hacker
would not be able to drop any tables or delete any important data.
When creating your user on your server it is essential to create your
own password and not the one displayed within the example. Here is a
useful password generator to create a secure password for the user. For
the connection to be established to your server the password within the
code and the PHP/SQL database have to be the same.
Create a MySQL table named “members”.
The code below creates a table with five fields (id, username, email,
password, salt). We use the CHAR datatype for fields we know the length
of, as the fields “password” and “salt” will always be 128 characters
long. Using CHAR here saves on processing power:
CREATE TABLE `secure_login`.`members` (
`id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
`username` VARCHAR(30) NOT NULL,
`email` VARCHAR(50) NOT NULL,
`password` CHAR(128) NOT NULL,
`salt` CHAR(128) NOT NULL
) ENGINE = InnoDB;
As we’ve said before, you can do this in whatever type of client you prefer.
Create a table to store login attempts.
We will use this table to store login attempts for a user. This is an
effective technique in which will make brute force attacks more
difficult:
CREATE TABLE `secure_login`.`login_attempts` (
`user_id` INT(11) NOT NULL,
`time` VARCHAR(30) NOT NULL
) ENGINE=InnoDB
Create a test row in table “members”.
It is extremely significant to always test your code below is a test user to test the database:
Username: test_user
Email: test@example.com
Password: 6ZaxN2Vzm9NUJT2y
SQL Code:
INSERT INTO `secure_login`.`members` VALUES(1, ‘test_user’, ‘test@example.com’,
‘00807432eae173f652f2064bdca1b61b290b52d40e429a7d295d76a71084aa96c0233b82f1feac45529e0726559645acaed6f3ae58a286b9f075916ebf66cacc’,
‘f9aab579fc1b41ed0c44fe4ecdbfcdb4cb99b9023abb241a6db833288f4eea3c02f76e0d35204a8695077dcf81932aa59006423976224be0390395bae152d4ef’);
Create a global configurations page
Create a folder called “includes” in the root directory of the application and then create a new PHP file in that directory.
Call the file psl-config.php. When working within a production
environment you should store this file and all other include files
outside of your servers root.
Storing your include files outside of the web server’s root means
that your file cannot be located using a direct URL. Which means if the
file was compromised root permissions of the file could not be displayed
as text in a browser window.
<?php /** * These are the database login details */ define(“HOST”,
“localhost”); // The host you want to connect to. define(“USER”,
“sec_user”); // The database username. define(“PASSWORD”,
“4Fa98xkHVd2XmnfK”); // The database password. define(“DATABASE”,
“secure_login”); // The database name. define(“CAN_REGISTER”, “any”);
define(“DEFAULT_ROLE”, “member”); define(“SECURE”, FALSE); // FOR
DEVELOPMENT ONLY!!!! ?>
Create the database connection page
This is the PHP code that we will use to connect to the mySQL database.
Create a new PHP file called db_connect.php in the application’s
includes directory and add the code below. This code can be added
wherever you like:
<?php
include_once ‘psl-config.php'; // As functions.php is not included
$mysqli = new mysqli(HOST, USER, PASSWORD, DATABASE);
Create the PHP Functions
These functions will do all the processing of the login script. Add
all of the functions to a page called functions.php in the includes
directory of the application.
Securely start a PHP session.
PHP sessions are known
not to be secure, therefore it is important not just to put
“session_start();” at the top of every page on which you want to use PHP
sessions. We are going to create a function called
“sec_session_start()”, this will start a PHP session in a secure way.
You should call this function at the top of any page in which you wish
to access a PHP session variable. If you are really concerned about
security and the privacy of your cookies, have a look at this article:
Create-a-Secure-Session-Managment-System-in-Php-and-Mysql.This function
makes your login script a whole lot more secure. It stops crackers
accessing the session id cookie through JavaScript (for example in an
XSS attack). Also the “session_regenerate_id()” function, which
regenerates the session id on every page reload, helps prevent session
hijacking. Note: If you are using HTTPS in your login application set
the “$secure” variable to true. In a production environment it is
essential that you use HTTPS.Create a new file called functions.php in
your application’s includes directory and add the following code to
it:<?php
include_once ‘psl-config.php';function sec_session_start() {
$session_name = ‘sec_session_id'; // Set a custom session name
$secure = SECURE;
// This stops JavaScript being able to access the session id.
$httponly = true;
// Forces sessions to only use cookies.
if (ini_set(‘session.use_only_cookies’, 1) === FALSE) {
header(“Location: ../error.php?err=Could not initiate a safe session (ini_set)”);
exit();
}
// Gets current cookies params.
$cookieParams = session_get_cookie_params();
session_set_cookie_params($cookieParams[“lifetime”],
$cookieParams[“path”],
$cookieParams[“domain”],
$secure,
$httponly);
// Sets the session name to the one set above.
session_name($session_name);
session_start(); // Start the PHP session
session_regenerate_id(true); // regenerated the session, delete the old one.
}Create the Login Function.
This function will check
the email and password against the database. It will return true if
there is a match. Add this function to your functions.php file:function
login($email, $password, $mysqli) {
// Using prepared statements means that SQL injection is not possible.
if ($stmt = $mysqli->prepare(“SELECT id, username, password, salt
FROM members
WHERE email = ?
LIMIT 1″)) {
$stmt->bind_param(‘s’, $email); // Bind “$email” to parameter.
$stmt->execute(); // Execute the prepared query.
$stmt->store_result();// get variables from result.
$stmt->bind_result($user_id, $username, $db_password, $salt);
$stmt->fetch();// hash the password with the unique salt.
$password = hash(‘sha512′, $password . $salt);
if ($stmt->num_rows == 1) {
// If the user exists we check if the account is locked
// from too many login attemptsif (checkbrute($user_id, $mysqli) == true) {
// Account is locked
// Send an email to user saying their account is locked
return false;
} else {
// Check if the password in the database matches
// the password the user submitted.
if ($db_password == $password) {
// Password is correct!
// Get the user-agent string of the user.
$user_browser = $_SERVER[‘HTTP_USER_AGENT’];
// XSS protection as we might print this value
$user_id = preg_replace(“/[^0-9]+/”, “”, $user_id);
$_SESSION[‘user_id’] = $user_id;
// XSS protection as we might print this value
$username = preg_replace(“/[^a-zA-Z0-9_\-]+/”,
“”,
$username);
$_SESSION[‘username’] = $username;
$_SESSION[‘login_string’] = hash(‘sha512′,
$password . $user_browser);
// Login successful.
return true;
} else {
// Password is not correct
// We record this attempt in the database
$now = time();
$mysqli->query(“INSERT INTO login_attempts(user_id, time)
VALUES (‘$user_id’, ‘$now’)”);
return false;
}
}
} else {
// No user exists.
return false;
}
}
}
The Brute Force Function.
Brute force attacks are
when a hacker tries thousands of different passwords on an account,
either randomly generated passwords or from a dictionary. In our script
if a user account has more than five failed logins their account is
locked.Brute force attacks are hard to prevent. A few ways we can
prevent them are using a CAPTCHA test, locking user accounts and adding a
delay on failed logins, so the user cannot login for another thirty
seconds.We strongly recommend using a CAPTCHA. As yet we have not
implemented this functionality in the example code, but hope to do so in
the near future, using SecureImage, since it does not require
registration. You may prefer something better known such as reCAPTCHA
from Google.Whichever system you decide on, we suggest you only display
the CAPTCHA image after two failed login attempts so as to avoid
inconveniencing the user unnecessarily.When faced with the problem of
brute force attacks, most developers simply block the IP address after a
certain amount of failed logins. But there are many tools to automate
the process of making attacks like these; and these tools can go through
a series of proxies and even change the IP on each request. Blocking
all these IP addresses could mean you’re blocking legitimate users as
well. In our code we’ll log failed attempts and lock the user’s account
after five failed login attempts. This should trigger the sending of an
email to the user with a reset link, but we have not implemented this in
our code. Here is the code for the checkbrute() function at the time of
writing. Add it to your functions.php code:function
checkbrute($user_id, $mysqli) {
// Get timestamp of current time
$now = time();// All login attempts are counted from the past 2 hours.
$valid_attempts = $now – (2 * 60 * 60);if ($stmt = $mysqli->prepare(“SELECT time
FROM login_attempts
WHERE user_id = ?
AND time > ‘$valid_attempts'”)) {
$stmt->bind_param(‘i’, $user_id);
// Execute the prepared query.
$stmt->execute();
$stmt->store_result();
// If there have been more than 5 failed logins
if ($stmt->num_rows > 5) {
return true;
} else {
return false;
}
}
}
Check logged in status.
We do this by checking
the “user_id” and the “login_string” SESSION variables. The
“login_string” SESSION variable has the user’s browser information
hashed together with the password. We use the browser information
because it is very unlikely that the user will change their browser
mid-session. Doing this helps prevent session hijacking. Add this
function to your functions.php file in the includes folder of your
application:function login_check($mysqli) {
// Check if all session variables are set
if (isset($_SESSION[‘user_id’],
$_SESSION[‘username’],
$_SESSION[‘login_string’])) {$user_id = $_SESSION[‘user_id’];
$login_string = $_SESSION[‘login_string’];
$username = $_SESSION[‘username’];// Get the user-agent string of the user.
$user_browser = $_SERVER[‘HTTP_USER_AGENT’];if ($stmt = $mysqli->prepare(“SELECT password
FROM members
WHERE id = ? LIMIT 1″)) {
// Bind “$user_id” to parameter.
$stmt->bind_param(‘i’, $user_id);
$stmt->execute(); // Execute the prepared query.
$stmt->store_result();if ($stmt->num_rows == 1) {
// If the user exists get variables from result.
$stmt->bind_result($password);
$stmt->fetch();
$login_check = hash(‘sha512′, $password . $user_browser);if ($login_check == $login_string) {
// Logged In!!!!
return true;
} else {
// Not logged in
return false;
}
} else {
// Not logged in
return false;
}
} else {
// Not logged in
return false;
}
} else {
// Not logged in
return false;
}
}Sanitize URL from PHP_SELF
This next function sanitizes the output from the PHP_SELF server
variable. It is a modificaton of a function of the same name used by the
WordPress Content Management System:
function esc_url($url) {
if (” == $url) {
return $url;
}
$url = preg_replace(‘|[^a-z0-9-~+_.?#=!&;,/:%@$\|*\'()\\x80-\\xff]|i’, ”, $url);
$strip = array(‘%0d’, ‘%0a’, ‘%0D’, ‘%0A’);
$url = (string) $url;
$count = 1;
while ($count) {
$url = str_replace($strip, ”, $url, $count);
}
$url = str_replace(‘;//’, ‘://’, $url);
$url = htmlentities($url);
$url = str_replace(‘&’, ‘&’, $url);
$url = str_replace(“‘”, ‘'’, $url);
if ($url[0] !== ‘/’) {
// We’re only interested in relative links from $_SERVER[‘PHP_SELF’]
return ”;
} else {
return $url;
}
}
The trouble with using the server variable unfiltered is that it can
be used in a cross site scripting attack. Most references will simply
tell you to filter it using htmlentities(), however even this appears
not to be sufficient hence the belt and braces approach in this
function.
Others suggest leaving the action attribute of the form blank, or set
to a null string. Doing this, though, leaves the form open to an iframe
clickjacking attack.
Create Processing Pages
Create the login processing page (process_login.php)
Create a file to process logins, called process_login.php in the
application’s includes directory. It goes in this directory because it
contains no HTML markup.
We will use the mysqli_* set of PHP functions as this is one of the most up-to-date mySQL extensions.
<?php
include_once ‘db_connect.php';
include_once ‘functions.php';
sec_session_start(); // Our custom secure way of starting a PHP session.
if (isset($_POST[‘email’], $_POST[‘p’])) {
$email = $_POST[‘email’];
$password = $_POST[‘p’]; // The hashed password.
if (login($email, $password, $mysqli) == true) {
// Login success
header(‘Location: ../protected_page.php’);
} else {
// Login failed
header(‘Location: ../index.php?error=1′);
}
} else {
// The correct POST variables were not sent to this page.
echo ‘Invalid Request';
}
Create a logout script.
Your logout script must start the session, destroy it and then
redirect to somewhere else. Note: it might be a good idea to add CSRF
protection here in case someone sends a link hidden in this page
somehow. For more information about CSRF you could visit Coding Horror.
The current code for logging out the user, which you should add to a
file called logout.php in the application’s includes directory, is:
<?php
include_once ‘functions.php';
sec_session_start();
// Unset all session values
$_SESSION = array();
// get session parameters
$params = session_get_cookie_params();
// Delete the actual cookie.
setcookie(session_name(),
”, time() – 42000,
$params[“path”],
$params[“domain”],
$params[“secure”],
$params[“httponly”]);
// Destroy session
session_destroy();
header(‘Location: ../index.php’);
Registration Page.
The registration code is included in two new files, called
register.php in the application’s root directory and register.inc.php in
the includes directory. It does the following things:
Obtains and validates the username the user wishes to adopt
Obtains and validates the user’s email address
Obtains and validates the password the user wants to use
Hashes the password and passes it back to the register.php page (i.e. it posts to itself)
Most of the validation is done in JavaScript, client side. This is
because the user has no motivation to circumvent these checks. Why would
a user want to create an account that would be less secure than
otherwise? We will discuss the JavaScript in the next section.
For now, just create the register.php file and include the following code in it:
<?php
include_once ‘includes/register.inc.php';
include_once ‘includes/functions.php';
?>
<!DOCTYPE html>
<html>
<head>
<meta charset=”UTF-8″>
<title>Secure Login: Registration Form</title>
<script type=”text/JavaScript” src=”js/sha512.js”></script>
<script type=”text/JavaScript” src=”js/forms.js”></script>
<link rel=”stylesheet” href=”styles/main.css” />
</head>
<body>
<!– Registration form to be output if the POST variables are not
set or if the registration script caused an error. –>
<h1>Register with us</h1>
<?php
if (!empty($error_msg)) {
echo $error_msg;
}
?>
<ul>
<li>Usernames may contain only digits, upper and lower case letters and underscores</li>
<li>Emails must have a valid email format</li>
<li>Passwords must be at least 6 characters long</li>
<li>Passwords must contain
<ul>
<li>At least one upper case letter (A..Z)</li>
<li>At least one lower case letter (a..z)</li>
<li>At least one number (0..9)</li>
</ul>
</li>
<li>Your password and confirmation must match exactly</li>
</ul>
<form action=”<?php echo esc_url($_SERVER[‘PHP_SELF’]); ?>”
method=”post”
name=”registration_form”>
Username: <input type=’text’
name=’username’
id=’username’ /><br>
Email: <input type=”text” name=”email” id=”email” /><br>
Password: <input type=”password”
name=”password”
id=”password”/><br>
Confirm password: <input type=”password”
name=”confirmpwd”
id=”confirmpwd” /><br>
<input type=”button”
value=”Register”
onclick=”return regformhash(this.form,
this.form.username,
this.form.email,
this.form.password,
this.form.confirmpwd);” />
</form>
<p>Return to the <a href=”index.php”>login page</a>.</p>
</body>
</html>
The register.inc.php file in the includes directory should contain the following code:
<?php
include_once ‘db_connect.php';
include_once ‘psl-config.php';
$error_msg = “”;
if (isset($_POST[‘username’], $_POST[‘email’], $_POST[‘p’])) {
// Sanitize and validate the data passed in
$username = filter_input(INPUT_POST, ‘username’, FILTER_SANITIZE_STRING);
$email = filter_input(INPUT_POST, ‘email’, FILTER_SANITIZE_EMAIL);
$email = filter_var($email, FILTER_VALIDATE_EMAIL);
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
// Not a valid email
$error_msg .= ‘<p class=”error”>The email address you entered is not valid</p>';
}
$password = filter_input(INPUT_POST, ‘p’, FILTER_SANITIZE_STRING);
if (strlen($password) != 128) {
// The hashed pwd should be 128 characters long.
// If it’s not, something really odd has happened
$error_msg .= ‘<p class=”error”>Invalid password configuration.</p>';
}
// Username validity and password validity have been checked client side.
// This should should be adequate as nobody gains any advantage from
// breaking these rules.
//
$prep_stmt = “SELECT id FROM members WHERE email = ? LIMIT 1″;
$stmt = $mysqli->prepare($prep_stmt);
// check existing email
if ($stmt) {
$stmt->bind_param(‘s’, $email);
$stmt->execute();
$stmt->store_result();
if ($stmt->num_rows == 1) {
// A user with this email address already exists
$error_msg .= ‘<p class=”error”>A user with this email address already exists.</p>';
$stmt->close();
}
$stmt->close();
} else {
$error_msg .= ‘<p class=”error”>Database error Line 39</p>';
$stmt->close();
}
// check existing username
$prep_stmt = “SELECT id FROM members WHERE username = ? LIMIT 1″;
$stmt = $mysqli->prepare($prep_stmt);
if ($stmt) {
$stmt->bind_param(‘s’, $username);
$stmt->execute();
$stmt->store_result();
if ($stmt->num_rows == 1) {
// A user with this username already exists
$error_msg .= ‘<p class=”error”>A user with this username already exists</p>';
$stmt->close();
}
$stmt->close();
} else {
$error_msg .= ‘<p class=”error”>Database error line 55</p>';
$stmt->close();
}
// TODO:
// We’ll also have to account for the situation where the user doesn’t have
// rights to do registration, by checking what type of user is attempting to
// perform the operation.
if (empty($error_msg)) {
// Create a random salt
//$random_salt = hash(‘sha512′, uniqid(openssl_random_pseudo_bytes(16), TRUE)); // Did not work
$random_salt = hash(‘sha512′, uniqid(mt_rand(1, mt_getrandmax()), true));
// Create salted password
$password = hash(‘sha512′, $password . $random_salt);
// Insert the new user into the database
if ($insert_stmt = $mysqli->prepare(“INSERT INTO members (username, email, password, salt) VALUES (?, ?, ?, ?)”)) {
$insert_stmt->bind_param(‘ssss’, $username, $email, $password, $random_salt);
// Execute the prepared query.
if (! $insert_stmt->execute()) {
header(‘Location: ../error.php?err=Registration failure: INSERT’);
}
}
header(‘Location: ./register_success.php’);
}
}
If there is no POST data passed into the form, the registration form
is displayed. The form’s submit button calls the JavaScript function
regformhash(). This function does the necessary validation checks and
submits the form when all is well. The JavaScript functions are
discussed in the next section.
If the POST data exists, some server side checks are done to sanitise
and validate it. NOTE that these checks are not complete at the time of
writing. Some of the issues are mentioned in the comments in the file.
At present, we just check that the email address is in the correct
format, that the hashed password is the correct length and that the user
is not trying to register an email that has already been registered.
If everything checks out, the new user is registered by writing a new record into the members table.
Create Javascript Files
Create sha512.js file
This file is an implementation in JavaScript of the hashing algorithm
sha512. We will use the hashing function so our passwords don’t get
sent in plain text.
The file can be downloaded from pajhome.org.uk
(It is also saved in the github repository)
Store your copy of this file in a directory called “js”, off the root directory of the application.
Create forms.js file
This file, which you should create in the js directory of the
application, will handle the hashing of the passwords for the login
(formhash()) and registration (regformhash()) forms:
function formhash(form, password) {
// Create a new element input, this will be our hashed password field.
var p = document.createElement(“input”);
// Add the new element to our form.
form.appendChild(p);
p.name = “p”;
p.type = “hidden”;
p.value = hex_sha512(password.value);
// Make sure the plaintext password doesn’t get sent.
password.value = “”;
// Finally submit the form.
form.submit();
}
function regformhash(form, uid, email, password, conf) {
// Check each field has a value
if (uid.value == ” ||
email.value == ” ||
password.value == ” ||
conf.value == ”) {
alert(‘You must provide all the requested details. Please try again’);
return false;
}
// Check the username
re = /^\w+$/;
if(!re.test(form.username.value)) {
alert(“Username must contain only letters, numbers and underscores. Please try again”);
form.username.focus();
return false;
}
// Check that the password is sufficiently long (min 6 chars)
// The check is duplicated below, but this is included to give more
// specific guidance to the user
if (password.value.length < 6) {
alert(‘Passwords must be at least 6 characters long. Please try again’);
form.password.focus();
return false;
}
// At least one number, one lowercase and one uppercase letter
// At least six characters
var re = /(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{6,}/;
if (!re.test(password.value)) {
alert(‘Passwords must contain at least one number, one lowercase and one uppercase letter. Please try again’);
return false;
}
// Check password and confirmation are the same
if (password.value != conf.value) {
alert(‘Your password and confirmation do not match. Please try again’);
form.password.focus();
return false;
}
// Create a new element input, this will be our hashed password field.
var p = document.createElement(“input”);
// Add the new element to our form.
form.appendChild(p);
p.name = “p”;
p.type = “hidden”;
p.value = hex_sha512(password.value);
// Make sure the plaintext password doesn’t get sent.
password.value = “”;
conf.value = “”;
// Finally submit the form.
form.submit();
return true;
}
In both cases, the JavaScript hashes the password and passes it in the POST data by creating and populating a hidden field.
Create HTML Pages
Create the login form (login.php).
This is an HTML form with two text fields, named “email” and
“password”. The form’s submit button calls the JavaScript function
formhash(), which will generate a hash of the password, and send “email”
and “p” (the hashed password) to the server. You should create this
file in the application’s root directory.
When logging in, it is best to use something that is not public, for
this guide we are using the email as the login id, the username can then
be used to identify the user. If the email is not displayed on any
pages within the wider application, it adds another unknown for anyone
trying to crack the account.
Note: even though we have encrypted the password so it is not sent in
plain text, it is essential that you use the HTTPS protocol (TLS/SSL)
when sending passwords in a production system. It cannot be stressed
enough that simply hashing the password is not enough. A
man-in-the-middle attack could be mounted to read the hash being sent
and use it to log in.
<?php
include_once ‘includes/db_connect.php';
include_once ‘includes/functions.php';
sec_session_start();
if (login_check($mysqli) == true) {
$logged = ‘in';
} else {
$logged = ‘out';
}
?>
<!DOCTYPE html>
<html>
<head>
<title>Secure Login: Log In</title>
<link rel=”stylesheet” href=”styles/main.css” />
<script type=”text/JavaScript” src=”js/sha512.js”></script>
<script type=”text/JavaScript” src=”js/forms.js”></script>
</head>
<body>
<?php
if (isset($_GET[‘error’])) {
echo ‘<p class=”error”>Error Logging In!</p>';
}
?>
<form action=”includes/process_login.php” method=”post” name=”login_form”>
Email: <input type=”text” name=”email” />
Password: <input type=”password”
name=”password”
id=”password”/>
<input type=”button”
value=”Login”
onclick=”formhash(this.form, this.form.password);” />
</form>
<p>If you don’t have a login, please <a href=”register.php”>register</a></p>
<p>If you are done, please <a href=”includes/logout.php”>log out</a>.</p>
<p>You are currently logged <?php echo $logged ?>.</p>
</body>
</html>
Create the register_success.php page
Create a new PHP web page called register_success.php, in the root
directory of the application. This is the page to which the user is
redirected after successfully registering. Of course you can make this
page anything you like or redirect to another page entirely (or even not
at all). It’s up to you. The page should be located in the root
directory of the application. The current register_success.php page that
we have written looks like this:
<!DOCTYPE html>
<html>
<head>
<meta charset=”UTF-8″>
<title>Secure Login: Registration Success</title>
<link rel=”stylesheet” href=”styles/main.css” />
</head>
<body>
<h1>Registration successful!</h1>
<p>You can now go back to the <a href=”index.php”>login page</a> and log in</p>
</body>
</html>
Create the error page
Create a new HTML page in the root directory of the application. Call
it error.php This is the page to which users will be directed if an
error occurs during the login or registration process, or when trying to
establish a secure session. The code given below simply provides a bare
bones error page. You will probably need something a bit more
sophisticated. However, please note that the input into the page must be
properly filtered to guard against XSS attacks. The example page code
is:
<?php
$error = filter_input(INPUT_GET, ‘err’, $filter = FILTER_SANITIZE_STRING);
if (! $error) {
$error = ‘Oops! An unknown error happened.';
}
?>
<!DOCTYPE html>
<html>
<head>
<meta charset=”UTF-8″>
<title>Secure Login: Error</title>
<link rel=”stylesheet” href=”styles/main.css” />
</head>
<body>
<h1>There was a problem</h1>
<p class=”error”><?php echo $error; ?></p>
</body>
</html>
Protecting Pages
Page Protection Script.
One of the most common problems with authentication systems is the
developer forgetting to check if the user is logged in. It is very
important you use the code below on every protected page to check that
the user is logged in. Make sure you use this function to check if the
user is logged in.
// Include database connection and functions here. See 3.1.
sec_session_start();
if(login_check($mysqli) == true) {
// Add your protected page content here!
} else {
echo ‘You are not authorized to access this page, please login.';
}
As an example of what you should do, we have included a sample
protected page. Create a file called protected_page.php in the root
directory of the application. The file should contain something like the
following:
<?php
include_once ‘includes/db_connect.php';
include_once ‘includes/functions.php';
sec_session_start();
?>
<!DOCTYPE html>
<html>
<head>
<meta charset=”UTF-8″>
<title>Secure Login: Protected Page</title>
<link rel=”stylesheet” href=”styles/main.css” />
</head>
<body>
<?php if (login_check($mysqli) == true) : ?>
<p>Welcome <?php echo htmlentities($_SESSION[‘username’]); ?>!</p>
<p>
This is an example protected page. To access this page, users
must be logged in. At some stage, we’ll also check the role of
the user, so pages will be able to determine the type of user
authorised to access the page.
</p>
<p>Return to <a href=”index.php”>login page</a></p>
<?php else : ?>
<p>
<span class=”error”>You are not authorized to access this
page.</span> Please <a href=”index.php”>login</a>.
</p>
<?php endif; ?>
</body>
</html>
Our application redirects to this page after a successful login. Your own implementation does not have to do this, of course.
Tips
With very few changes these example scripts can be modified to work with other SQL systems such as SQLite or PostgreSQL.
If you’re wanting to use
a different hashing algorithm rather than sha512, try Whirlpool. Avoid
using Gost, sha1 (Unless thoroughly salted and in multiple iterations),
and as already stated, md5. Encourage your users to create strong,
unique passwords with both uppercase and lowercase letters, numbers, and
symbols. Consider having your users create a separate login name from
their username for added security.
Stay away from the md5() function in login scripts, the md5 hashing algorithm is now considered insecure.
Use HTML and CSS to format the login form and output pages to your
liking.WarningsThe login page and the Registration page must use HTTPS.
The scripts in this article do not force you to do this and, indeed, you
may find it easier not to during development. But you should not use
these scripts in a production environment unless you are using HTTPS.
The use of a CAPTCHA on the login page is highly recommended to make
brute force and DoS attacks more difficult. We recommend that the
CAPTCHA appear on the form after two failed login attempts. This is not
yet implemented in the example code.
Make sure that the user cannot see your PHP script, which may occur due
to an incorrect server setup. There is a possibility of the users
gathering information about your database names and passwords if your
PHP code is visible. Ideally any scripts that are included in other
scripts or pages should be located in a directory outside of the
server’s file system and referenced using a relative path e.g. include
‘../../includes/myscript.inc.php’.
You may get a better solution than this by using a framework such as
Zend 2, Symfony or CakePHP. All of these frameworks have arrangements
for secure sessions and modules to assist with the login process. You
may also find you write better applications if you use a framework.
Nothing is 100% secure. Remember to stay in tune with the latest security news to keep improving the security of your scripts.
Centralized sign in solutions exist and are known as Single Sign-On, or
SSO. Depending on the need, these may offer superior alternatives to
framework sign in solutions since a single login is able to span
multiple disparate software applications which may reside on multiple
domains. Examples of popular SSO solutions are Barebones SSO, Jasig CAS,
and JOSSO.
The Anti Brute Force of this script, that locks a user account, can be
misused very easily. We strongly recommend that you use an anti-brute
force technique such as a CAPTCHA.
Within the global media there are instances of websites and data bases being compromised all the time. Keeping sensitive data secure...
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