The issue is on the eldesk-tech-support.php page.
You are getting the name of the file to download from a hidden form element. That allows a would-be hacker to change the value of the hidden form element to download whatever file they want from your site.
Instead you should remove the hidden form element and get the file name from the recordset directly. So instead of this on line 17:
WA_DFP_DownloadFile("WA_DownloadResult1", "downloads/helpdesk/", "".((isset($_POST["hidden"]))?$_POST["hidden"]:"") ."", "".((isset($_POST["hiddenname"]))?$_POST["hiddenname"]:"") ."", false, false, false, "", "", "", "");
}
Instead use:
WA_DFP_DownloadFile("WA_DownloadResult1", "downloads/helpdesk/", "".($rsHelpdesk->getColumnVal('File',false)) ."", "".($rsHelpdesk->getColumnVal('Title')) ."", false, false, false, "", "", "", "");
}
Then you can delete your two hidden form elements. That way the file name can't be manipulated. Paths in other locations aren't relevant and can be left as they are.