Honda Civic type R

Hi,

I am an amature mechanic and am trying to strip the rear suspension of my 2002 civic type R.

Part of the rear lower arm of the is conected to the upright Via three 12 pointed star headed bolts. I am wondering what type of bolt this is and what i can use to remove them. I have tried all my imperial and metric sockets on it all avail. its close to a 17mm but all that socket does it begin to round the poins off. the head looks like a 12 pointed male torques.

Any ideas what tool i need? i dont want to grind them off!!

Thank you

Ben