he technology on infrared remote control is widely applied in human daily life. It is also applied in the place with a top security level. Infrared remote control signal is regarded as a simple, safe and clean resource that can help us control the electrical appliances nearby. In this paper, we build IREXF, a novel infrared optical covert channel from a well-protected air-gapped network via a malicious infrared module implanted previously into a keyboard. A malware preinstalled in the air-gapped PC receives the data from the malicious infrared module to study the infrared surroundings in the air-gapped network. Once a suitable appliance is found, infrared remote control commands will be sent in a proper time. With the development of technology on Internet of Things, more and more electrical appliances can access Internet. Those infrared command signals exfiltrating out of the air-gapped network can be received by an appliance without any malicious configuration. In our experiment, via a smart TV set-top box, the rate of the covert channel can be up to 2.62 bits per second without any further optimization. Finally, we give a list of countermeasures to detect and eliminate this kind of covert channels.