5G is changing the way User Equipment (UE) integrates with networks and services. Features like network slicing and device-to-device (D2D) networking are blurring traditional network boundaries into a distributed model. These evolutions are leading to the development of novel security, privacy, and spectrum management paradigms, which will hopefully enable safe adoption. This paper proposes a standalone testbed to impact and measure cybersecurity, privacy, and spectrum management at various points within the network. Our proposed testbed is relatively low cost and is based on commercial-off-the-shelf (COTS) hardware and open-source software. Using the Contained cellular User equipment Environment (CUE) testbed, we can investigate many potential 5G issues in ways previously not accessible. Our approach enables researchers to focus on various threat-based features by capturing and potentially modifying packets and RF from the physical layer and up.