In recent years, the popularity of IoT (Internet of Things) applications and services has brought great convenience to people's lives, but ubiquitous IoT has also brought many security problems. Among them, advanced persistent threat (APT) is one of the most representative attacks, and its continuous outbreak has brought unprecedented security challenges for the large-scale deployment of the IoT. However, important research on analyzing the attribution of APT malware samples is still relatively few. Therefore, we propose a classification method for attribution organizations with APT malware in IoT using machine learning. It aims to mark the real attacking organization entities to better identify APT attack activity and protect the security of IoT. This method performs feature representation and feature selection based on APT behavior data obtained from devices in the Internet of Things and selects the features with a high degree of differentiation among organizations. Then, it trains a multiclass model named SMOTE-RF that can better deal with imbalance and multiclassification problems. Our experiments on real dynamic behavior data are combined to verify the effectiveness of the method proposed in this paper for attribution analysis of APT malware samples and achieve good performance. Our method could identify the organization behind complex APT attacks in IoT devices and services.