The track she uses during live performances
Here http://www.zshare.net/video/99160137e7a1476f/

File not found, i heard this a few weeks ago anyway, its fake, it was put together by a fan from one of her live performances, a bit of research will show you its sung differently everytime she goes onto stage.

Why would it need to be leaked?

I don't think it's any of kind of big secret. I mean she didn't try to hide the mining when she sang it on X-factor.