How come? - FTP brute force attack

[The late XV105]

Thanks for all that; very interesting to read.

The questions now are:

1. Did anything get transferred even though the FTP logs only show a connection, not any activity, and the two "public" folders were empty at the time? (The private folders were chokka with files)
2. Has anything been silently installed on the (Flavour of Linux) NAS and should I therefore reset it to as-delivered defaults and start again?

I guess the real answer is "who knows?", so having plugged the hole (switched off UPnP) I need to stop worrying, reconfigure the NAS from factory defaults, and for my sanity, also forget about going anywhere near MioNet or any other service that gives remote access!