Prepare cake mix as directed on package, adding vanilla.
Bake as directed on package for cupcakes. Cool cupcakes on wire rack.
Tint frosting black with 1/2 teaspoon black food color. Frost cupcakes, mounding frosting in center of cupcake to create a dome shape. Sprinkle cupcakes with chocolate sprinkles. Cut string licorice into 2-inch lengths and use for the spider legs. Attach candy-coated pieces to flat side of chocolate chips with some frosting. Use for the eyes.