Greetings,

A site I developed was recently compromised, most likely by a brute force or Rainbow Table attack. The original log-in script did not have a SALT, passwords were stored in MD5.

Below is an updated script, complete with SALT and IP address banning. In addition, it will send a Mayday email & SMS and disable the account should the same IP address or account attempt 4 failed log-ins. Please look it over and let me know what could be improved, what is missing, and what is just plain strange.

Many thanks!

<?php
    //Start session
    session_start();
    //Include DB config
    include $_SERVER['DOCUMENT_ROOT'] . '/includes/pdo_conn.inc.php';

    //Error message array
    $errmsg_arr = array();
    $errflag = false;

    //Function to sanitize values received from the form. Prevents SQL injection
    function clean($str) {
        $str = @trim($str);
        if(get_magic_quotes_gpc()) {
            $str = stripslashes($str);
        }
        return $str;
    }

    //Define a SALT, the one here is for demo
    define('SALT', '63Yf5QNA');

    //Sanitize the POST values
    $login = clean($_POST['login']);
    $password = clean($_POST['password']);
    //Encrypt password
    $encryptedPassword = md5(SALT . $password);
    //Input Validations
    //Obtain IP address and check for past failed attempts
    $ip_address = $_SERVER['REMOTE_ADDR'];
    $checkIPBan = $db->prepare("SELECT COUNT(*) FROM ip_ban WHERE ipAddr = ? OR login = ?");
    $checkIPBan->execute(array($ip_address, $login));
    $numAttempts = $checkIPBan->fetchColumn();
    //If there are 4 failed attempts, send back to login and temporarily ban IP address
    if ($numAttempts == 1) {
        $getTotalAttempts = $db->prepare("SELECT attempts FROM ip_ban WHERE ipAddr = ? OR login = ?");
        $getTotalAttempts->execute(array($ip_address, $login));
        $totalAttempts = $getTotalAttempts->fetch();
        $totalAttempts = $totalAttempts['attempts'];
        if ($totalAttempts >= 4) {
            //Send Mayday SMS
            $to = "[email protected]";
            $subject = "Banned Account - $login";
            $mailheaders = 'From: [email protected]' . "\r\n";
            $mailheaders .= 'Reply-To: [email protected]' . "\r\n";
            $mailheaders .= 'MIME-Version: 1.0' . "\r\n";
            $mailheaders .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
            $msg = "<p>IP Address - " . $ip_address . ", Username - " . $login . "</p>";
            mail($to, $subject, $msg, $mailheaders);
            $setAccountBan = $db->query("UPDATE ip_ban SET isBanned = 1 WHERE ipAddr = '$ip_address'");
            $setAccountBan->execute();
            $errmsg_arr[] = 'Too Many Login Attempts';
            $errflag = true;    
        }
    }
    if($login == '') {
        $errmsg_arr[] = 'Login ID missing';
        $errflag = true;
    }
    if($password == '') {
        $errmsg_arr[] = 'Password missing';
        $errflag = true;
    }

    //If there are input validations, redirect back to the login form
    if($errflag) {
        $_SESSION['ERRMSG_ARR'] = $errmsg_arr;
        session_write_close();
        header('Location: http://somewhere.com/login.php');
        exit();
    }

    //Query database
    $loginSQL = $db->prepare("SELECT password FROM user_control WHERE username = ?");
    $loginSQL->execute(array($login));
    $loginResult = $loginSQL->fetch();

    //Compare passwords
    if($loginResult['password'] == $encryptedPassword) {
        //Login Successful
        session_regenerate_id();
        //Collect details about user and assign session details
        $getMemDetails = $db->prepare("SELECT * FROM user_control WHERE username = ?");
        $getMemDetails->execute(array($login));
        $member = $getMemDetails->fetch();
        $_SESSION['SESS_MEMBER_ID'] = $member['user_id'];
        $_SESSION['SESS_USERNAME'] = $member['username'];
        $_SESSION['SESS_FIRST_NAME'] = $member['name_f'];
        $_SESSION['SESS_LAST_NAME'] = $member['name_l'];
        $_SESSION['SESS_STATUS'] = $member['status'];
        $_SESSION['SESS_LEVEL'] = $member['level'];
        //Get Last Login
        $_SESSION['SESS_LAST_LOGIN'] = $member['lastLogin'];
        //Set Last Login info
        $updateLog = $db->prepare("UPDATE user_control SET lastLogin = DATE_ADD(NOW(), INTERVAL 1 HOUR), ip_addr = ? WHERE user_id = ?");
        $updateLog->execute(array($ip_address, $member['user_id']));
        session_write_close();
        //If there are past failed log-in attempts, delete old entries
        if ($numAttempts > 0) {
            //Past failed log-ins from this IP address. Delete old entries
            $deleteIPBan = $db->prepare("DELETE FROM ip_ban WHERE ipAddr = ?");
            $deleteIPBan->execute(array($ip_address));
        }
        if ($member['level'] != "3" || $member['status'] == "Suspended") {
            header("location: http://somewhere.com");
        } else {
            header('Location: http://somewhere.com');
        }
        exit();
    } else {
        //Login failed. Add IP address and other details to ban table
        if ($numAttempts < 1) {
        //Add a new entry to IP Ban table
        $addBanEntry = $db->prepare("INSERT INTO ip_ban (ipAddr, login, attempts) VALUES (?,?,?)");
        $addBanEntry->execute(array($ip_address, $login, 1));
        } else {
            //increment Attempts count 
            $updateBanEntry = $db->prepare("UPDATE ip_ban SET ipAddr = ?, login = ?, attempts = attempts+1 WHERE ipAddr = ? OR login = ?");
            $updateBanEntry->execute(array($ip_address, $login, $ip_address, $login));
        }
        header('Location: http://somewhere.com/login.php');
        exit();
    }
?>