DIAGNOSIS Yeah, this one's common. The oil is leaking from the tank vent or a cracked oil line inside the saw. The MS 170's oiling system is gravity-fed, so if it's overfilled or the vent is blocked/open, it'll just drain out.
FIX First, only fill the oil tank right before you use the saw, and don't store it full. If it still leaks, check the oil tank vent. It's a small one-way valve. If it's stuck open, oil will seep out. You can try cleaning it, but often it needs replacing.
IF THAT DIDN'T WORK The oil feed line that runs from the tank to the pump might have a crack or have come disconnected. You'll need to split the crankcase to get to it, which is a bigger job.
HEADS UP Storing the saw on its side, especially on the oil tank side, will make this leak way worse. Always store it upright or on the opposite side.