It entered the solar system at a speed of around 23km/s. That's painfully slow to actually travel through space and bridge any kind of distance in a reasonable amount of time. You need hundreds of years to get through the solar system at that speed let alone get to it from somewhere else.
Maybe it's just a probe like our voyager 2 probe which travels at around 16 km/s. Could have travelled through the milky way for millions of years and just happens to randomly cross our solar system. Whatever civilization made that thing is probably long gone by now. I mean at least that would be a possibility.
Anyway, it's never Aliens until you can safely sort out any other possible explanation. So for the moment I will assume that this thing has a natural origin.
Official member of VGC's Nintendo family, approved by the one and only RolStoppable. I feel honored.