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Does anyone have a technical explanation of how gps spoofing works?

Johnny555 9y ago
Here's an article on GPS spoofing and some potential countermeasures: http://spectrum.ieee.org/telecom/security/protecting-gps-from-spoofers-is-critical-to-the-future-of-navigation http://spectrum.ieee.org/telecom/security/protecting-gps-fro...
deleted 9y ago
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blackguardx 9y ago
I'm not sure this is technical enough, but this gist is as follows. GPS signals are extremely weak. They are below the background noise floor (you can't see them with a spectrum analyzer) and can only be received by convolving with a pseudorandom code (PN code). Because they are so weak, an adversary can overpower them and cause receivers to "lock on" as long as rogue signal is well designed. GPS signals are fairly simple. They mainly encode precise time information from atomic clocks orbiting the earth. By receiving 4 time signals from 4 atomic clocks in known orbits, one's position can be precisely known. This is a hard attack, but not not impossible. The Iranians are rumored to have used this technique to down a stealth drone the US was using for spy purposes.
- foota 9y ago
  I'm sure it's beyond me without a lot of work, but what makes the attack difficult for someone with the right background?
  - blackguardx 9y ago
    I think this has become much easier with the rise of SDR. You would mainly have to know alot about the orbits of the GPS satellites to be able to convincingly simulate their signals from a given point on the globe.
    - throwaway613834 9y ago
      > You would mainly have to know alot about the orbits of the GPS satellites to be able to convincingly simulate their signals from a given point on the globe. Do GPS receivers validate satellite orbits? Do they even know what all the satellite orbits are supposed to be?
hokkos 9y ago
Here is some slides from Defcon 23 : https://media.defcon.org/DEF%20CON%2023/DEF%20CON%2023%20presentations/DEFCON-23-Lin-Huang-Qing-Yang-GPS-Spoofing.pdf https://media.defcon.org/DEF%20CON%2023/DEF%20CON%2023%20pre... They did a record, replay with a USRP B210 and GPS antenna. And here is a project that generates GPS baseband signal data streams for bladeRF, HackRF, and USRP. https://github.com/osqzss/gps-sdr-sim https://github.com/osqzss/gps-sdr-sim

Here's an article on GPS spoofing and some potential countermeasures: http://spectrum.ieee.org/telecom/security/protecting-gps-from-spoofers-is-critical-to-the-future-of-navigation http://spectrum.ieee.org/telecom/security/protecting-gps-fro...

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blackguardx 9y ago

I'm not sure this is technical enough, but this gist is as follows. GPS signals are extremely weak. They are below the background noise floor (you can't see them with a spectrum analyzer) and can only be received by convolving with a pseudorandom code (PN code). Because they are so weak, an adversary can overpower them and cause receivers to "lock on" as long as rogue signal is well designed. GPS signals are fairly simple. They mainly encode precise time information from atomic clocks orbiting the earth. By receiving 4 time signals from 4 atomic clocks in known orbits, one's position can be precisely known. This is a hard attack, but not not impossible. The Iranians are rumored to have used this technique to down a stealth drone the US was using for spy purposes.

foota 9y ago
I'm sure it's beyond me without a lot of work, but what makes the attack difficult for someone with the right background?
- blackguardx 9y ago
  I think this has become much easier with the rise of SDR. You would mainly have to know alot about the orbits of the GPS satellites to be able to convincingly simulate their signals from a given point on the globe.
  - throwaway613834 9y ago
    > You would mainly have to know alot about the orbits of the GPS satellites to be able to convincingly simulate their signals from a given point on the globe. Do GPS receivers validate satellite orbits? Do they even know what all the satellite orbits are supposed to be?

hokkos 9y ago

Here is some slides from Defcon 23 : https://media.defcon.org/DEF%20CON%2023/DEF%20CON%2023%20presentations/DEFCON-23-Lin-Huang-Qing-Yang-GPS-Spoofing.pdf https://media.defcon.org/DEF%20CON%2023/DEF%20CON%2023%20pre... They did a record, replay with a USRP B210 and GPS antenna. And here is a project that generates GPS baseband signal data streams for bladeRF, HackRF, and USRP. https://github.com/osqzss/gps-sdr-sim https://github.com/osqzss/gps-sdr-sim