Hi All,
Just update what I have found. I found nothing after running Wordfence, My conclusion is /uploads/ folder was set at 777 which allowed everyone or hacking to have writing permission; it mean they can modify or insert any files into the server,
In order to avoid this for WP website owner:
1. Make sure all folders are set at 755, and files are set at 644, in particular:
/wp-content/
/wp-admin/
/wp-includes/
2. All folder under /wp-content/ must set at 755 too:
/wp-contents/themes/
/wp-contents/plugins/
/wp-contents/uploads/
and all others inside /wp-contents/
3. All folders under /wp-admin/ and /wp-includes/ should be 755 and files at 644.
4. Failure of doing the above, hackers enjoy attacking your websites.
When should you do that?
When you restore your website from a backup on a new server or the same one because file/folder permissions are normally set back to 777/666, etc.
Many thanks for this such a great community.
(I will try Rechard's advice to install a protection on SSH)
Cheers