In January, a DJI Phantom quadcopter drone crashed on the White House lawn. The operator had apparently lost control of the drone while he was flying it outside his apartment window in Washington D.C. For some, this was proof that cheap, small drones such as the Phantom could pose a serious threat to public safety. On March 18, 2015, the House Committee on Homeland Security Subcommittee on National Oversight and Efficiency held a hearing to explore the nature of these threats and how to prevent them from taking place. “[W]e need a better understanding of the technological solutions that exist to deal with these threats and what law enforcement needs to better respond when a small UAS is used for illegal activity,” Chairman Scott Perry (R-Pa.) said in his opening statement to the subcommittee.
Not everyone is convinced the off-the-shelf drones pose a threat to public safety. In a recent article at Motherboard on the Congressional hearing, Carl Franzen argues that small size of these drones makes it unlikely that these machines will be used to inflict serious damage. The point of origin for much of the concern around the use of small drones as weapons was an incident in Germany in 2013 when, as a prank, a member of the Pirate Party flew a Parrot quadcopter drone toward Angela Merkel during a campaign rally. The drone made it within a few feet of the Chancellor before police forced the operator to land the aircraft. It wasn’t hard for members of law enforcement to imagine a scenario in which, instead of as a prank, the drone had been used as a weapon. The types of drones that are of particular concern are small, commercially available quadcopter drones that can be purchased for a few hundred dollars. Here is what you need to know about domestic drone attacks:
- Reconnaissance and Surveillance: In this scenario, an actor could use a drone to reconnoiter targets for attack or monitor the actions of individuals or law enforcement. The utility of off-the-shelf drones for reconnaissance and surveillance has already been proven in battle spaces like the civil war in Ukraine. The rapid spread of hobbyist drones makes this scenario both the most likely threat involving drones and the most difficult to identify. Just in the past few years, there have been many cases in which it was difficult to determine whether the drone was being used for recreational use, newsgathering, activism, or for an activity that could result in harming public safety. The challenges in recognizing the threat could pose an additional harm: an overreaction by individuals on the ground, leading to a potentially violent escalation.
- Smuggling: There have been multiple cases where criminal organizations or individuals have used drones to smuggle illicit material, usually across borders or into prisons. In November 2013, a drone was spotted flying over the walls of a prison in Quebec, and in March 2014, a similar event occurred in Australia. Earlier this year, a drone carrying drugs was discovered crashed just south of the U.S.-Mexico border.
- Electronic Attack: At the 2014 Black Hat security conference in Singapore, information security firm SensePost revealed Snoopy, a drone that can hack into WiFi and steal the data on those networks. In what is known as a “karma attack,” Snoopy can also impersonate a network that an unsuspecting user might join, whereupon the code would steal that users’ data. This method could be used to particular effect in a crowded environment where many people have their cell phones automatically searching for WiFi networks. In February, it was revealed that AdNear, a Singapore-based marketing firm, was experimenting with commercially available drones that would help to deliver targeted advertisements by collecting data on cell phones.
- Kinetic Attack: In this scenario, an attacker might strap guns or explosives to a drone and fly it into people or structures to inflict physical damage or loss of life. The targets of these attacks may be individuals, buildings, or transportation infrastructure such as commercial airliners. In 2011, 26-year-old Rezwan Ferdaus was arrested “in an FBI undercover operation and accused of planning to build small explosive-laden drones to attack the Pentagon and the U.S. Capitol, according to law enforcement officials.” In an article at Wired, Kevin Poulsen reported that, at a conference hosted by the Department of Homeland Security in January, counterterrorism officials displayed several models of drones that were outfitted with inert explosives.
- WMD Attack: An attacker could use a drone to spray a weaponized chemical or biological agent over, for example, a crowd of people or in a downtown area. This scenario predates the rise of mass-market drones like the Phantom. In 2003, then-Secretary of State Colin Powell warned that Iraq was planning on using drones to deliver chemical weapons. A claim that we now know to be false. The Pentagon, however, is not ruling out this scenario, and in October 2014, it solicited information on countermeasures for drones armed with chemical or biological agents like Sarin.
Limitations of Drones as Weapons
With some of these scenarios, it is unlikely that drones pose a unique threat, at least not any more so than an attacker on the ground. Even if one were able to acquire lightweight explosives or chemical agents to attach to a drone, the physical size of commercially available drones creates limitations on the attacker’s ability to inflict harm. A DJI Phantom, for example, has a payload capacity of around 1.8 lbs. Off-the-shelf drones generally cannot fly for more than 20 to 30 minutes, and they have a limited range, so an attacker would need to be close to the target. Heavier payloads also diminish range and flight times. Of greater consequence is the potential that an attacker would use a drone to inflict psychological harm—to produce terror—or to conduct assassinations. Even in these scenarios, however, the natural operational limitations on covert activity of this kind of sophistication and complexity would likely doom any plans to use drones for lethal effect.
In his statement to Congress on March 18, Dr. Greg McNeal cautioned against overstating the risks posed by drones and encouraged federal agencies to undertake comprehensive risk assessments before embarking on developing countermeasures. “Congress should ensure that agencies are as concerned with the probability of harm as they are of the possibility of a worst-case scenario,” McNeal explained.
A number of countermeasures have been proposed to defend against potential threats posed by drones. Some of these defenses are already being developed by university researchers and private companies while others are being considered by law enforcement and the military.
- Geo-fencing: Unlike most of the other defenses, this method is already in place before the drone takes off. With geofencing, the drone manufacturer engineers into the firmware of the drone a virtual boundary on the geographical areas where the operator cannot fly, forcing the drone to ground if operators trespass into these areas. In the wake of the White House drone incident, Chinese drone manufacturer DJI announced that it was introducing geo-fencing into its next firmware update to prevent users from flying into Washington D.C. airspace. In a previous firmware update, DJI used geo-fencing to create “no-fly zones” for airports.
- Spoofing: This involves fooling the GPS on the drone by creating a series of false coordinates that allows the defenders to take control of the drone. This defense mechanism was demonstrated in 2012 by a team led by Professor Todd Humphreys at the University of Texas-Austin. It is also believed that the Iranians used spoofing to bring down a U.S. Sentinel spy drone in 2011. Read On: Statement by Professor Todd Humphreys to the Subcommittee on National Oversight and Efficiency.
- Jamming: This is another electronic attack that attempts to sever the command link between the attacking drone and the ground station, forcing the drone to fly without intervention by the operator or, in extreme cases, transferring command of the drone to the defender. However, by switching to autonomous flight mode, the drone can avoid some forms of jamming.
- Lasers: While it may be unlikely that the Secret Service is going to mount lasers (also known as directed energy) on the roof of the White House, lasers are believed to have potential to be effective for countering drones. In November 2014, China unveiled a laser system that is designed specifically for shooting small drones. According to Chinese state media Xinhua, the laser will “play a key role in ensuring security during major events in urban areas.” Read On: “What You Need to Know About Lasers” – Dan Gettinger // CSD
- Surface-to-Air Missiles: In July 2014, Israel used a Patriot missile to shoot down an incoming reconnaissance drone from Gaza. However, as Jon Stewart pointed out in the wake of the White House drone incident, this method of bringing down drones is highly impractical, if not impossible in a domestic threat environment.
- Firearms: This is one of the most common ways to bring down small drones. Whether it’s Turkish riot police shooting down a newsgathering drone during a protest or an angry man in New Jersey taking aim at his neighbors drone, guns are seemingly the go-to solution for many people. Shooting a gun at a drone is also the most likely scenario to result in someone on the ground getting injured from falling parts—particularly in a metropolitan area—or, obviously, from stray bullets.
- Drone-on-Drone: This countermeasure involves defending drones that would intercept attacking drones in the air. For the most part, this countermeasure is purely speculative. It could involve drones equipped with large nets catching smaller drones in the air. Or, as the Navy demonstrated last year, swarms of drones could intercept larger manned or unmanned attackers. In 2012, Timothy Chung, an assistant professor at the Naval Postgraduate School, experimented with a project called Aerial Battle Bots that pitted swarms of UAVs against each other.
Limitations of Countermeasures
Drones are difficult to shoot down and even harder to detect. As Professor Todd Humphreys noted to Congress on March 18, the small size of drones and the use of non-reflective airframe materials like styrofoam make it hard for conventional systems like radar to track these aircraft. In December 2014, the North American Aerospace Defense Command launched an enormous tethered blimp at Andrews Air Force base in Maryland that, because of its position 10,000 ft. in the air, can improve radar detection capabilities around Washington D.C. Professor Humphreys surveyed a range of alternative detection measures including acoustic sensing, radio emission sensing, and electro-optical sensing that could provide additional tracking abilities. It is not hard to imagine that in the near future, law enforcement agencies could spread multiple types of sensors around sensitive locations and city limits that will provide a layered system of defense.
- Local Law Enforcement: In recent years, police have struggled to develop ways of preventing drones from becoming threats to public safety. Part of the problem is the difficulty in recognizing that a drone does in fact pose a threat. Another difficulty is that there has been little in the way of direction from the federal government on the proper ways to respond to the growth of drone hobbyists. In January, the Federal Aviation Administration asked local law enforcement for help in preventing unauthorized or unsafe drone operations, releasing a guide for officers on these issues. Read On: Statement by Chief Richard Beary to Congress on security threats posed by drones.
- Secret Service: On March 10, the Secret Service started running tests to defend the White House against drones. The late-night tests, which will run for several weeks, explore ways of tracking and intercepting drones using electronic techniques like jamming.
- National Counterterrorism Center: In January, the New York Times reported that the NCTC was increasingly concerned by the threats posed by drones. Over the past year and a half, an NCTC working group on drones has grown from four members to 65.
- Congress: There has been a push by both state and national legislatures in the United States to ban weaponized drones and restrict the use of drones by private individuals and law enforcement. On March 17, Reps. Zoe Lofgren (D-Calif.), and Ted Poe (R-Texas) introduced legislation in Congress that would ban drones equipped with firearms by all parties.