Eric Jedermann

• In the last decade the field of satellite communication systems has experienced a golden age. Due to technological improvements the launch costs for satellites were reduced dramatically, so even private companies can launch their satellites. Today, large constellations of hundreds or thousands of satellites are launched into the low earth orbit (LEO). The internationally operating networks have the potential to connect users in the most remote areas. Thereby, the systems provide a wide variety of services, such as low data rate IoT communication, high throughput broadband access, and mobile connectivity. This dissertation provides an introduction to communication satellite systems in general and focuses on two properties of LEO communication satellites that are unique in their combination: The broadcasting of traffic and the predictable, continuous mobility of low earth orbit satellites. The combination of these properties has not received much attention in satellite security research in the past. We aim to fill this gap by analyzing the potential of those two key properties for new attack vectors and possible defense mechanisms. To investigate the effect of those properties, we developed a receiver network to make distributed traffic measurements of LEO satellite systems possible. To support the international research in this field, the network is open source and low cost. Currently, our instance of the network consists of 12 receivers that are internationally distributed, with a focus on central Europe. The possibility to receive broadcasted traffic of other satellite users in combination with predictable satellite spot beam movements leads to an attack vector threatening the location privacy of satellite users. This vector applies to every communication satellite system with predictable spot beam alignment. By using our receiver network, we were able to demonstrate the feasibility of this attack in the real world. On the other hand, the possibility to observe traffic with multiple receivers and the known positions of satellites in their orbits can be used as a defense mechanisms. As an example for this, we developed an authentication scheme that determines if the signal was send by a valid satellite.