With the rapid growth of Internet of Things (IoT) devices and evolving 5G/6G networks, satellite communication has become extremely important, which can provide the capability of sending information from one place to another via a communication satellite in orbit around the Earth. Due to the increasing needs, the Internet traffic is naturally part of satellite communication, carrying a large number of sensitive or private information and data. As such, the proliferation of satellites may bring increased security risks. Motivated by this concern, in this work, we aim to investigate the potential security breaches in satellite communication, with a specific focus on geostationary orbit (GEO) satellites. In particular, we firstly set up an experimental environment to collect data from satellites that the hardware equipment supports, and then perform a risk assessment based on NIST. In terms of our experimental findings and risk analysis, we identify a total of 15 threat sources that may cause various security issues. In the end, we discuss potential solutions to enhance the security and lessons learnt in our setup.