It's a hack generally implemented through third party programs, or web pages, designed to specifically target a computer when a certain program or action is taken.
1.You tried downloading a hack from the wrong place
2.You visited a false wonderking website on accident
3. A very skilled hacker had time to actually put the virus into your computer through the system directly through your wk terminal. (that would take a lot of time and skill)
4.It isn't a virus at all, but an error that your computer/antivirus thinks is a virus.
Any of these (with the exception of 3) is very possible. And if you are legit, that narrows it down to two.
If your antivirus doesn't take care of it, run file check, or re-download the game if needed.