There are 14 points to the star. This points to one specific option of doing it in camera. The lens has 7 blades.

The diffraction spikes formed by the lens form at two spots for each blade, one major one and one minor one 180 degrees from the major one. You will notice that every other star point is shorter than its neighbors. As I said, this points to a 7 bladed lens aperture.

You will often see 6 (which only shows 6 points), 14 (from 7) and 8 (from 8) though more exist. Lenses that don't try to have a circular aperture (rounded blades) will produce a more pronounced star effect.

Given this, I doubt it was done post processing. Possible, but as I said, I doubt it.

Its also possible to force the effect with a star filter. These are filters that have been scored with lines that will cause similar patterns similar to the diffraction spikes from point light sources (its on everything, but tends not to be as noticeable though it does reduce the sharpness in the rest of the image - you'll frequently see it used in night photographs).

For example, the Tiffen Star filters come in a variety of points and arrangement of points. It all depends on how the filter was scored. They are also sometimes called 'cross screens'. B&H has an entire category for its star filters.