I already wrote this story in the comments to some other rant, still it's pretty funny.

So, i was modding my wii u by messing with system files, the only way to do this is to run an homebrew that hosts an ftp server so you can connect with your pc, the thing is, this server was not protected and allowed anonymous login, not an issue if you have a firewall.
BUT i had this console in the DMZ on the router for online play.
~You can see where this is going~
While doing stuff from my pc i started seeing a lot of entries on the console's log and i didn't understand why, i thought filezilla was doing some shit so i closed it but the log was still going, then i realized and quickly shut the server down.
Then i disabled the DMZ and went back to check what happened (unfortunately the log was only shown on screen and not saved, by closing the server i lost it) so looks like the attacker uploaded a lot of files with random names in pretty much every folder.
Due to the random names, I don't know which are system files and which attacker's files so i just kept them there. And today they should still be there.

--Random thinking--
What if the attacker also stole some files, he was hoping to get photos or valuable documents, but just got the console's system files and he thought something along the lines of "wtf is even this".
Also, how likely is that an ip scanner script gets to my ip in the 5 minutes i run the server, and (on the attacker side) how likely is to hack a server just to find out that's a wii u (the least successful console in the last generation)...

Moral of the story: double check your firewall if you are going to run an unprotected server.
That's it, stay safe :P