Owing to the widespread use of smartphones, various online games based on mobile platforms are being launched. Although mobile games have the advantage of better accessibility compared to PC games, there is a limitation in that it is difficult to input specific actions. To overcome this limitation, game companies apply autoplay systems to support users. Autoplay (with macro or game bot programs) without human interaction was previously regarded as a cheating play. To provide a more comfortable and easy gaming experience to users, most mobile games currently provide autoplay functionality. Such introduction means that along with gold farming groups (GFGs), all users can use a game bot. Therefore, game companies prevent profit-producing activities of GFGs by introducing an in-game economic system in which a real money trading (RMT) is impossible. However, GFGs still operate by abusing an auction house. Our study uses the three-month transaction logs of a mobile game that introduces an auction house as an in-game economic system. We observe the abuse that makes RMTs possible through the auction house and propose a method of identifying abuse solely through a transaction log. We analyzed the GFGs using the identified abuse and confirmed that the GFG consists of a single role.