i didnt know miners cant be infected with a trojan..
Yeah happens all the time if you download stuff.
Just having unprotected VNC server software's enough. Many GPU miners still use VNC for remote interfacing, and some programs actually restrict password length as low as 8 characters. Especially mining on dubious fly-by-night altcoin pools and putting your IP out there as someone who uses crypto, there're a good few risks many don't account for -- like, say you keep a hot wallet backup on a MS Homegroup-shared folder and have your mining PCs in the homegroup with read access to the backup. Someone doesn't need to brute force the PC with a wallet on it, they just need to get into one of the mining PCs and search the network for files.