请批评这个PHP登录脚本

Question

我开发的网站最近受到了损害,最有可能是暴力破解或彩虹桌攻击.原始登录脚本没有SALT,密码存储在MD5中.

下面是一个更新的脚本,完成SALT和IP地址禁止.此外,如果相同的IP地址或帐户尝试登录失败,它将发送五月天电子邮件和短信并禁用该帐户.请仔细看看,让我知道可以改进什么,缺少什么,以及什么是奇怪的.

<?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 = "admin@somewhere.com";
            $subject = "Banned Account - $login";
            $mailheaders = 'From: noreply@somewhere.com' . "\r\n";
            $mailheaders .= 'Reply-To: noreply@somewhere.com' . "\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();
    }
?>

编辑

好的,这是我尝试随机盐.首先,创建要插入表中的salt:

define('SALT_LENGTH', 15);
function createSalt()
{
    $key = '!@#$%^&*()_+=-{}][;";/?<>.,';
    $salt = substr(hash('sha512',uniqid(rand(), true).$key.microtime()), 0, SALT_LENGTH);
    return $salt;
}
$salt = createSalt()
//More prep for entering into table...

然后用随机盐生成哈希:

$hash = hash('sha256', $salt . $pw); //$pw is the cleaned user submitted password

当用户登录时,使用存储的随机生成的盐比较存储的哈希:

$loginHash = hash('sha256', $dbSalt . $pw);
if ($loginHash == $dbHash) {
    //Logged in
} else {
    //Failed
}

那怎么样？

Answer 1

好的,这里有几个:

1. 你不应该再使用md5了.你可以,但有更好的方法(如sha512与hash()功能一起使用).

2. 我也会使用更长的静态盐.我建议至少64个字符(毕竟,它是写入时计算的最小开销,但更难以猜测).

3. 我还会添加一个动态(随机)盐.为每个用户生成一个新用户,并将其与密码哈希一起存储(通常用:字符分隔它们).这样,即使你的静态盐被泄露,也需要为你的数据库中的每个密码生成一个新的彩虹表(或至少迭代一次)...

4. 不要基于IP地址信任或操作任何非时间的东西.大多数ISP使用一种形式的NAT,其中从一个IP中可以看到多个用户(并且这将随着IPv4名称空间的耗尽而变得更加普遍).如果你想限速或暂时阻止IP地址,那很好.但是不要禁止他们......

5. 您的clean()函数应首先检查字符串,或强制它为字符串:( $str = is_string($str) ? trim($str) : (string) $str;).它根本不会阻止sql注入.但是stripslashes调用是必要的(确切地说你是如何拥有的)允许代码在已magic_quotes_gpc设置的服务器上工作(它将尝试为你转义引号)......所以请保持这种状态.

6. 更好地格式化代码.创建处理相关任务的函数.这样你就没有75行程序代码来查看发生了什么.更好的是,将它包装在一个类中,并将常见任务(db访问等)移动到它们自己的类中.并记住正确缩进.可读性是王道,所以不要走捷径......

编辑:至于如何验证密码,首先获取盐渍哈希,然后使用存储的盐重新计算哈希值.(makeSaltedHash我在下面展示的功能额外使用了一种称为键拉伸的东西.

function validatePassword($password, $hash) {
    list($oldHash, $salt) = explode(':', $hash, 2);
    $newHash = makeSaltedHash($password, $salt);
    return $hash == $newHash;
}

function makeSaltedHash($password, $salt = '') {
    if (empty($salt)) {
        $salt = makeRandomSalt(mt_rand(64, 128));
    }
    $hash = hash('sha512', $password . $salt . SALT);
    for ($i = 0; $i < 50; $i++) {
        $hash = hash('sha512', $password . $salt . SALT . $hash);
    }
    return $hash . ':' . $salt;
}

function makeRandomSalt($length = 64) {
    $salt = '';
    for ($i = 0; $i < $lenght; $i++) {
        $salt .= chr(mt_rand(33, 126));
    }
    return $salt;
}