wordpress searching hacked

Hello, i found some site linked to my site in ahref by some kind of backlink from some strange domains like 819987.7w0atz2(.)com or some draft domain that I don't know. [mydomain.com/?cat=大奖TTG老虎机注册送彩金www.djyl18.com&s=大奖TTG老虎机注册送彩金www.djyl18.com] this url like something (.) com/?cat come from...