The Yellow Sac Spider is a common name for certain species of spiders in the genus Cheiracanthium, family Miturgidae. They are usually pale yellow in color and has a body length of 6 to 10 mm. Being nocturnal, yellow sac spiders are active in the night and search for their prey. They don't build webs. Instead they construct sacs in protected areas and that's why they are known as Sac Spiders. Their bite is believed to be venomous to humans. Therefore, they should be handled very carefully.
Yellow Sac Spider
Thanks to Mr. Glen of spiderz rule for identification help.