Bulk-add featured images in posts with no featured image

I have a site with loads of posts (news items). Some posts don't have featured images yet. Adding the images to those posts (few hundreds) is a tedious task. We basically want to add 1 and the same image to all the posts without a featured image.

Is there a way to do this in bulk? Like ADD 'this image' to ALL 'posts' (not pages) WHERE 'featured_image' is empty. I really hope there's a plugin for that. Can't find it though.