Sounds can knock drones out of the sky

A natural property of all objects can be used to disrupt a drone's gyroscope with sound

Some drones can be knocked out of the sky using focused beams of sound, according to new research.

Some drones can be knocked out of the sky using focused beams of sound, according to new research.

Knocking a drone out of the sky is sometimes possible using an invisible weapon -- sound.

The vulnerability in some drones comes from a natural property of all objects -- resonance. Take a wine glass: if a sound is created that matches the natural resonant frequency of the glass, the resulting effects could cause it to shatter.

The same principle applies to components inside drones. Researchers at the Korea Advanced Institute of Science and Technology (KAIST) in Daejon, South Korea, analyzed the effects of resonance on a crucial component of a drone, its gyroscope. Their paper will be presented next week at the 24th USENIX Security Symposium in Washington, D.C.

A gyroscope keeps a drone balanced, providing information on its tilt, orientation and rotation, allowing for micro-adjustments that keep it aloft. Hobbyist and some commercial drones use inexpensive gyroscopes that are designed as integrated circuit packages.

In some cases, the gyroscopes have been designed to have resonant frequencies that are above the audible spectrum, said Yongdae Kim, a professor in KAIST's electrical engineering department. But others are still in the audible spectrum, making them vulnerable to interference from intentional sound noise.

Matching the resonant frequency of a gyroscope causes it to generate erroneous outputs, which have an effect on its flight, Kim said.

Kim's team studied 15 types of gyroscopes from four vendors. Most came from two companies, STMicroelectronics and InvenSense, whose gyroscopes are used in a variety of drones. Seven of the gyroscopes resonated at their own resonant frequencies when encountering a matching sound.

At the resonant frequency, the gyroscopes "spit out very strange outputs," Kim said.

To compensate for this, many gyroscopes are designed so their resonant frequencies are higher than the audible range. For example, many mouses used for gaming are designed to avoid the matching of resonant frequencies to avoid game disruptions, Kim said.

It is possible, however, to affect some kinds of drones using sound. For their tests, the researchers attached to a drone a small, consumer-grade speaker that was wirelessly connected to a nearby laptop.

The drone takes off normally, but when the right noise is played through the speaker, it smacks into the ground.

"When the gyroscope starts fluctuating, it affects the rotor speed directly," Kim said.

At 140 decibels, it would be possible to affect a vulnerable drone up from around 40 meters away, Kim said.

For a real attack, it's not going to be possible to attack a drone by attaching a speaker to it. But Kim's team did experiment a bit with more realistic attack scenarios, analyzing the distance that would be needed from a drone to a sound source.

The main problem is aiming and tracking. "We are not Lockheed Martin or Northrop Grumman," Kim said. "We cannot make those weapons in our lab."

Still, they tried some small-scale efforts. In one experiment, Kim's team embedded an audio module into a police shield. The problem with the shield is that it is difficult to continually track a drone in order to disrupt it. Even if the attack is initially successful, the drone starts to move so erratically that it become hard to track.

"Directionality matters a lot," he said. "It was pretty difficult."

In another attempt, they built a kind of sonic wall, comprised of an archway containing speakers. The problem with the archway is that the drone passes too quickly through the ideal attack zone.

But there are a variety of sound-related offensive and defensive devices already on the market. For example, the LRAD Corporation makes the 450XL, which it terms an "acoustic hailing device." It can be mounted on a vehicle or a tripod and can project a voice message up to 1,700 meters.

Japanese fisherman have used sound devices against environmentalists trying to disrupt their whaling operations, focusing intense, loud sounds against pursuers.

Combined with a tracking radar, those type of devices could make such attacks on drones more viable. So how to defend against a sound attack? The key is insulating the gyroscopes from interference, using shielding or foam.

"With a good casing, you can prevent most of our attacks," Kim said.

The research paper was also co-authored by Yunmok Son, Hocheol Shin, Dongkwan Kim, Youngseok Park, Juhwan Noh, Kibum Choi and Jungwoo Choi, all of KAIST.

Send news tips and comments to Follow me on Twitter: @jeremy_kirk

Join the CSO newsletter!

Error: Please check your email address.

Tags USENIXInvenSensesecuritySTMicroelectronicsKorea Advanced Institute of Science and Technology

More about AdvancedLockheed MartinNorthrop GrummanSTMicroelectronicsTechnologyTwitter

Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by Jeremy Kirk

Latest Videos

  • 150x50

    CSO Webinar: Will your data protection strategy be enough when disaster strikes?

    Speakers: - Paul O’Connor, Engagement leader - Performance Audit Group, Victorian Auditor-General’s Office (VAGO) - Nigel Phair, Managing Director, Centre for Internet Safety - Joshua Stenhouse, Technical Evangelist, Zerto - Anthony Caruana, CSO MC & Moderator

    Play Video

  • 150x50

    CSO Webinar: The Human Factor - Your people are your biggest security weakness

    ​Speakers: David Lacey, Researcher and former CISO Royal Mail David Turner - Global Risk Management Expert Mark Guntrip - Group Manager, Email Protection, Proofpoint

    Play Video

  • 150x50

    CSO Webinar: Current ransomware defences are failing – but machine learning can drive a more proactive solution

    Speakers • Ty Miller, Director, Threat Intelligence • Mark Gregory, Leader, Network Engineering Research Group, RMIT • Jeff Lanza, Retired FBI Agent (USA) • Andy Solterbeck, VP Asia Pacific, Cylance • David Braue, CSO MC/Moderator What to expect: ​Hear from industry experts on the local and global ransomware threat landscape. Explore a new approach to dealing with ransomware using machine-learning techniques and by thinking about the problem in a fundamentally different way. Apply techniques for gathering insight into ransomware behaviour and find out what elements must go into a truly effective ransomware defence. Get a first-hand look at how ransomware actually works in practice, and how machine-learning techniques can pick up on its activities long before your employees do.

    Play Video

  • 150x50

    CSO Webinar: Get real about metadata to avoid a false sense of security

    Speakers: • Anthony Caruana – CSO MC and moderator • Ian Farquhar, Worldwide Virtual Security Team Lead, Gigamon • John Lindsay, Former CTO, iiNet • Skeeve Stevens, Futurist, Future Sumo • David Vaile - Vice chair of APF, Co-Convenor of the Cyberspace Law And Policy Community, UNSW Law Faculty This webinar covers: - A 101 on metadata - what it is and how to use it - Insight into a typical attack, what happens and what we would find when looking into the metadata - How to collect metadata, use this to detect attacks and get greater insight into how you can use this to protect your organisation - Learn how much raw data and metadata to retain and how long for - Get a reality check on how you're using your metadata and if this is enough to secure your organisation

    Play Video

  • 150x50

    CSO Webinar: How banking trojans work and how you can stop them

    CSO Webinar: How banking trojans work and how you can stop them Featuring: • John Baird, Director of Global Technology Production, Deutsche Bank • Samantha Macleod, GM Cyber Security, ME Bank • Sherrod DeGrippo, Director of Emerging Threats, Proofpoint (USA)

    Play Video

More videos

Blog Posts

Market Place