Apple logo on the back of iPhone

Just check it's serial number in https://checkcoverage.apple.com/in/en/;jsessionid=node0p1qoxc306bju1pbifd8f0eglk852810.node0. you can take serial number from Settings > General > About. And also check your model number. Model number will be found in Settings > General > About. Picture shows below will help you in Model number checking.

Of course it is fake. Anyone will be able to tell just by looking at the build quality. Where did you buy it from? Go and immediately return in.

For your next purchase go to checkcoverage: https://checkcoverage.apple.com/mt/en/;jsessionid=node01d5g1mz52hh2u1mpb87m8kiej9664931.node0

Here you can verify your serial number. When you bought the phone didnt you get the slightest hint that it is a fake phone? Anyways, how much did you pay for it?