【笔记】网易微专业-Web安全工程师-04.WEB安全实战-2.暴力破解

else {
    // Login failed
    sleep( 2 );
    echo "<pre><br />Username and/or password incorrect.</pre>";
}

<form action="#" method="GET">
    Username:<br />
    <input type="text" name="username"><br />
    Password:<br />
    <input type="password" AUTOCOMPLETE="off" name="password"><br />
    <br />
    <input type="submit" value="Login" name="Login">
    <input type=‘hidden‘ name=‘user_token‘ value=‘ac9dabf93f796a0b905e64e5326e579c‘ />
</form>

<?php
if( isset( $_GET[ ‘Login‘ ] ) ) {
    // Check Anti-CSRF token
    checkToken( $_REQUEST[ ‘user_token‘ ], $_SESSION[ ‘session_token‘ ], ‘index.php‘ );
......
// Generate Anti-CSRF token
generateSessionToken();
?>

<?php
if( isset( $_POST[ ‘Login‘ ] ) ) {
    // Check Anti-CSRF token
    checkToken( $_REQUEST[ ‘user_token‘ ], $_SESSION[ ‘session_token‘ ], ‘index.php‘ );
    // Sanitise username input
    $user = $_POST[ ‘username‘ ];
    $user = stripslashes( $user );
    $user = mysql_real_escape_string( $user );
    // Sanitise password input
    $pass = $_POST[ ‘password‘ ];
    $pass = stripslashes( $pass );
    $pass = mysql_real_escape_string( $pass );
    $pass = md5( $pass );
    // Default values
    $total_failed_login = 3;
    $lockout_time       = 15;
    $account_locked     = false;
    // Check the database (Check user information)
    $data = $db->prepare( ‘SELECT failed_login, last_login FROM users WHERE user = (:user) LIMIT 1;‘ );
    $data->bindParam( ‘:user‘, $user, PDO::PARAM_STR );
    $data->execute();
    $row = $data->fetch();
    // Check to see if the user has been locked out.
    if( ( $data->rowCount() == 1 ) && ( $row[ ‘failed_login‘ ] >= $total_failed_login ) )  {
        // User locked out.  Note, using this method would allow for user enumeration!
        //echo "<pre><br />This account has been locked due to too many incorrect logins.</pre>";
        // Calculate when the user would be allowed to login again
        $last_login = $row[ ‘last_login‘ ];
        $last_login = strtotime( $last_login );
        $timeout    = strtotime( "{$last_login} +{$lockout_time} minutes" );
        $timenow    = strtotime( "now" );
        // Check to see if enough time has passed, if it hasn‘t locked the account
        if( $timenow > $timeout )
            $account_locked = true;
    }
    // Check the database (if username matches the password)
    $data = $db->prepare( ‘SELECT * FROM users WHERE user = (:user) AND password = (:password) LIMIT 1;‘ );
    $data->bindParam( ‘:user‘, $user, PDO::PARAM_STR);
    $data->bindParam( ‘:password‘, $pass, PDO::PARAM_STR );
    $data->execute();
    $row = $data->fetch();
    // If its a valid login...
    if( ( $data->rowCount() == 1 ) && ( $account_locked == false ) ) {
        // Get users details
        $avatar       = $row[ ‘avatar‘ ];
        $failed_login = $row[ ‘failed_login‘ ];
        $last_login   = $row[ ‘last_login‘ ];
        // Login successful
        echo "<p>Welcome to the password protected area <em>{$user}</em></p>";
        echo "<img src=\"{$avatar}\" />";
        // Had the account been locked out since last login?
        if( $failed_login >= $total_failed_login ) {
            echo "<p><em>Warning</em>: Someone might of been brute forcing your account.</p>";
            echo "<p>Number of login attempts: <em>{$failed_login}</em>.<br />Last login attempt was at: <em>${last_login}</em>.</p>";
        }
        // Reset bad login count
        $data = $db->prepare( ‘UPDATE users SET failed_login = "0" WHERE user = (:user) LIMIT 1;‘ );
        $data->bindParam( ‘:user‘, $user, PDO::PARAM_STR );
        $data->execute();
    }
    else {
        // Login failed
        sleep( rand( 2, 4 ) );
        // Give the user some feedback
        echo "<pre><br />Username and/or password incorrect.<br /><br/>Alternative, the account has been locked because of too many failed logins.<br />If this is the case, <em>please try again in {$lockout_time} minutes</em>.</pre>";
        // Update bad login count
        $data = $db->prepare( ‘UPDATE users SET failed_login = (failed_login + 1) WHERE user = (:user) LIMIT 1;‘ );
        $data->bindParam( ‘:user‘, $user, PDO::PARAM_STR );
        $data->execute();
    }
    // Set the last login time
    $data = $db->prepare( ‘UPDATE users SET last_login = now() WHERE user = (:user) LIMIT 1;‘ );
    $data->bindParam( ‘:user‘, $user, PDO::PARAM_STR );
    $data->execute();
}
// Generate Anti-CSRF token
generateSessionToken();
?>