Hackers don't make pirated OS so that they can tap in your bank accounts etc, the algorithm involved in an OS program script would be far too complex for them to comprehend, plus a windows update would flag it up before you yourself clocked on. They only break the code to authenticate your copy with Microsoft's servers, they who kernel is still original stock, a similar technique used a few years ago when unlocking iPhones.
I have been using a pirated version of 7 since '09, fully activated with constant windows update and have not had one single problem with it.