Airborne cyber attacks against drones have been conducted by hackers, criminals and state-sponsored actors. Unmanned Aerial Vehicles (UAVs) – also known as “drones” – are gaining popularity in many sectors of society. Pioneered by the military, law enforcement as well as criminals have used them. Hobbyists gather to race while retail stores will soon ship purchases with these. To reach the market quickly, security is often an afterthought. Vendors and operators underestimate the intent and capability of hackers to target their products. Thus researchers took up the challenge of showing their vulnerabilities. Reviewing current security issues and past incidents highlight the issues and their solutions before critical failures in drones causes harm. However before doing so, let’s quickly study the basic inner workings of drones.
Drones: How do they work?
Drones range from the highly complex multi-million dollars military aircraft to the toy models available for a hundred dollars. Despite this disparity, their overall architecture can be divided into 1) the aircraft and 2) the ground station. The aircraft regroups sensors and controllers needed to fly while the ground station includes software and hardware to send commands wirelessly. The ground station includes wireless transceivers, flight planning software, aircraft maintenance applications and the operators. The aircraft hosts the flight controller which processes data from sensors, avionics, communications, autopilot systems and in some cases, weapons.
Operators send navigation commands via a Remote Controller (RC), which relay information via a Line-of-Sight (LOS) communication channel. In low-end drones, standard wireless networking protocols are used while higher-end ones leverage satellite communications. Data from the ground station is transmitted to receivers or the aircraft and processed by the flight controller. The controller manages the outputs from various sensors including the GPS receiver, camera and propellers. Audiovisual data is relayed to the ground station via a second communication channel or stored on removable medias. Predefined routes can be programmed using flight planning software to make the aircraft autonomous.
Cyberattacks against Drones
Communication channels are the obvious attack vector. Unfortunately calls for encryption are often downplayed and proprietary protocols, despite some may believe, are not safe from reverse engineering and hijacking. In 2009, Iraqi militants found out that unencrypted videos feed from U.S. drones were available by pointing a satellite receiver towards the drone, greatly compromising operational effectiveness. While secure channels are critical, weak encryption is as good as no encryption. It was discovered in 2015 that scrambled video feeds between Israeli UAVs and ground stations were easily decrypted using open-source software. An attacker only required knowledge of the proper frequencies. That being said, even good encryption is no remedy when employed with vulnerable key management systems. A fact rarely discussed by security vendors pitching solutions.
Lower end drones have been hacked via known vulnerabilities in wireless networking protocols. SkyJack is an air-to-air network attack drone that detects surrounding wireless connections of vulnerable drones and reroutes them to itself, allowing the remote operator to to hijack the target. This deauthentification technique used is similar to the one seen against home wireless networks. Other attacks included cracking WEP networks between the flight planning software and the remote controller, allowing the intruder to issue commands to the remote controller.
Communicational channels are not the only weak points. Drones require information from their environment in order to navigate. The information is captured by the sensors and transmitted to the flight controller for processing. Therefore providing invalid inputs to the sensors will disrupt the aircraft. Invalid GPS data is one of the explanation for the unexpected landing of a U.S. RQ-170 sentinel in Iran. The Iranian military maintain they spoofed GPS data by broadcasting stronger signals than the ones from valid GPS satellites. By doing so they forced the sentinel to land. Such an attack was proven possible on other models. The second theory is that an internal malfunction forced an emergency landing. In either case, this incident highlighted two issues: implicit trust of sensory data sources and unexpected effects of internal errors.
Security is not only about networks; it’s also about robustness of the internal software. MalDrone is a malware compiled for ARM Linux which allows to spawn a remote shell on the target drone. The attacker intercepts an unencrypted channel between the ground station and a vulnerable aircraft to upload the malware, allowing direct access to the operating system (OS). An alternative tactic could aim to modify the firmware of the flight controller or sensors. Users rarely validate the integrity of the firmware downloaded online, allowing backdoors to be injected via man-in-the-middle attacks. Hackers may leverage social engineering to send malicious updates or exploit a vulnerability to execute arbitrary code and gain remote access to the drone. Like many Internet-of-Things (IoT) devices, drones are seldom updated by their owners and could remain vulnerable for a long period of time.
As drones continue to find increased usage in civil society, they will be subjected to further analysis. Engineers and operators should never underestimate both the capability and intent of malicious actors to target their product either for fun, profit or other malicious goals. Lessons learned by the software industry remain mostly unimplemented:; lack of secure communications, no firmware integrity validation, loose or absent security controls and slow patching of critical vulnerabilities. The success of the Mirai botnet is a result of these failings and drones are not exempt. Unlike the distributed denial of service observed, compromised drones may raise safety concerns and must therefore be secured.