With regards to brightening this photo just a little, you need to be careful you don't brighten ALL of it, as parts of the sky are correctly exposed, throwing the rest into underexposure. So in post you want to make sure you only brighten up those parts and leave the bright parts of the sky as they are, since everything else will make them too bright. Which means you need a programme that offers you the opportunity to mask off those parts of your picture that you don't want to touch, only brightening what you really want to. See what I mean?
I feel this is a photo worth the while you'll have to spend on it in post.