why do you think people putting up viruses would be a thing? and i'm not aware of the technicalities, but i'm pretty sure the way mod files (for most games at least) work doesn't allow them to interfere with anything other than the game. i.e., something would have to be run to put something malicious on your computer.
Torquescript viruses, backdoors in servers, wiping saves, screenshots, permanently destroying blockland data, psychological trauma in the form of remote control asshattery.
It might not be bank accounts, but it's extremely destructive.