We present a novel approach for extending the input space around unmodified mobile devices. Using built-in front-facing cameras of unmodified handheld devices, GlassHands estimates hand poses and gestures through reflections in sunglasses, ski goggles or visors. Thereby, GlassHands creates an enlarged input space, rivaling input reach on large touch displays. We introduce the idea along with its technical concept and implementation. We demonstrate the feasibility and potential of our proposed approach in several application scenarios, such as map browsing or drawing using a set of interaction techniques previously possible only with modified mobile devices or on large touch displays. Our research is backed up with a user study.