With the booming growth of unmanned aerial vehicles (UAVs, drones) in recent years, especially for commercial and recreational aerial photography UAVs, the safety issues of civilians and security problems of sensitive information are causing much concern. Some studies have confirmed that many attacks against UAVs are highly connected to the vulnerabilities of the civil global positioning system (GPS). The transparency and predictability of unencrypted civil GPS signals make them easy to counterfeit. Furthermore, owing to the development of software-defined radio (SDR) in recent years, launching a civil GPS spoofing attack is no longer expensive. GPS spoofing against drones using SDR devices has severely threatened their flight security and personal safety. In this study, we demonstrated three UAV hijacking attacks using HackRF One, an SDR device, with corresponding open source projects. We also proved that launching such threatening attacks is not expensive and such attacks are easy to control. We also propose some possible approaches to enhance the security of UAV location information.