Even with an M-Card you can get hacked now, which is pretty sad. So there is no way to be 100% safe, just try changing your password more often and not sharing your account with anyone.
Most common way to get someone m-card information is key-loggers but that would take sometime to get your information. I seen some advanced ones that screen shots or your screen then you would be screwed. change your m-card weekly and you should be fine. If I had +9 set i would change it every other day since it takes 1min to do ^^ learn from your mistakes. Oh and buy a costume that way you wont attract hackers.
most likely you shared info either being email or the actual info for the account. I used to be a head GM and GM of multiple private servers and most of the people that complained they were hacked after I researched it I found out they just shared info with the wrong person.
