DIAGNOSIS That's almost certainly bar and chain oil leaking from the tank. It's a very thin oil designed to flow easily, and it can seep out if the saw is stored in a certain position.
FIX The proper storage position for this saw is on its side, with the bar and the oil tank cap facing upward. Never store it flat on its base or on the bar tip. Before long-term storage, it's also a good practice to empty the oil tank. Run the saw until the oil is mostly used up, or you can carefully drain it by removing the fill cap (over a rag or container).
IF THAT DIDN'T WORK If it's leaking even when stored correctly, check the oil tank cap's O-ring. It's a small rubber ring on the cap. Make sure it's clean, not cracked or deformed, and seated properly. A damaged O-ring won't seal the tank.
HEADS UP Don't use motor oil or thick grease as bar oil—it's too thick for the small pump and will cause worse problems. Use only proper bar and chain oil. The leak is messy, but it's usually a storage issue, not a sign the saw is broken.