from this link ,
http://www.mantisbt.org/bugs/view.php?id=4988

I implement private attachment from these variable to prevent report for secret attachment.
$g_allow_view_own_attachments = ON;
$g_allow_download_own_attachments = ON;
$g_allow_delete_own_attachments = OFF;

$g_download_attachments_threshold = DEVELOPER;
$g_delete_attachments_threshold = DEVELOPER;
$g_view_attachments_threshold = DEVELOPER;

so user role "reporter" can see the files that they uploaded only.
and if another reporter login to the same issue , they not see the files BUT NOW they will see the line from "issue history". So it's a very kind of you if you will fixed this too.