Yep, and if you don't look for them, you can be darn sure someone else is looking for them. I heard about an incident from a friend where a GitHub repo was created accidentally public (ran out of private repos and I guess the failure mode back in the day was just make it public) and that repo had developer level access keys in it. Some enterprising fellow was scanning public repos for this, grabbed the keys, opened thousands and thousands of the biggest GPU machines they could get on AWS and started mining bitcoins. They were nice enough not to delete production to make room for more bitcoin miners.