According to the College of Agricultural Sciences at Penn State, brown spiders with white spots on their underbellies are generally identified as European garden spiders, also known as cross weavers. These spiders are usually found in Washington and Oregon and from Pennsylvania northward through New England and parts of Canada.
The European garden spider typically makes its home near exterior lighting, where nighttime lights draw in the bugs it feasts on for sustenance. It is also common to find this spider species building a web in lighted stairwells in rural homes. The dots on the underbelly of the spider form a cross, which is the reason for its cross weaver eponym.