Is malleability an extensive property or an intensive property?
Malleability is certainly an intensive property.
Malleability (from malleus, hammer) is the ability to be hammered out into a sheet. Metals tend to be be highly malleable, and highly ductile (able to be drawn out into a wire). Some metals (for instance sodium) can be rolled out to a thin sheet at room temperature, simply by using a long metal cylinder as a rolling pin.
I always classified extensive properties as describing the extent of the substance, mass, volume, length, charge.