Your bird could have scale mites. Try to post a pic and maybe someone more knowledgeable than myself will be able to tell you for sure. I've read on here that some mites can be treated with sevin dust or food grade diatomaceous earth but don't take my word for it because I've never had a problem with mites. Sorry I couldn't be more helpful. Good luck!
Scrub there legs in warm water to remove the nastys. You can make a paste out of Sevin dust and vaseline. Or just coat there legs with bag balm, diaper cream, vaseline or anything of that nature. If is not a bad idea to coat all the chickens legs.