Ask HN: Why do we still have replay attacks on our cars?
So today my car got stolen in front of my house. It was a 2021's Hyundai Tucson.
We clearly see on some cameras in the street that it took less than 1 minute for the thief to take it.
I was not aware that the "replay" attack (as I understand consists simply in listening to my keys signal through my door and replicating it to open and start the car), so my key was not far at all.
So my question is, why is my worthless github account secured by a free android 2FA app which makes replicating attacks impossible, and my 50K€ car secured by the dumbest only-one-forever-the-same key ever?
Is it not possible in the car keys to make some pgpsign-like technology?
(Also I am now aware of the tiktok trend of stealing these Kia and Hyundai car because their security is so easy to abuse)
26 comments
[ 3.4 ms ] story [ 57.0 ms ] threadHow complex would a device have to be to not be trivially defeated by a replay attack? How do you get both ends to reliably communicate without requiring an always-on internet connection in both the dongle and the vehicle to sync timing or some other state? What do you do when the manufacturer no longer exists or doesn't want to pay for servers to enable people to drive "old models"?
Also I remember some Renault Espace in France which had a dongle but then you had to put it somewhere specifically in the car to start it. Adding an NFC/RFID chip could solve part of the problem maybe...
But yes you are right this require maintenance.
Not very.
>How do you get both ends to reliably communicate without requiring an always-on internet connection in both the dongle and the vehicle to sync timing or some other state?
You don't need an Internet connection or server. TLS would do the job just fine.
Around $5 complex (though I lost track of actual prices for few years).
How do you get both ends to reliably communicate
You choose a suitable networking stack and communicate. Secure messaging is a solved problem and doesn’t require “internet”.
But it seems like a risible source of complexity.
It's more convenient to leave your keys in your pocket or your bag, then to rummage around for them.
There's a terminology problem here. I don't believe this is a replay attack (same open command is replayed later and works), those are largely solved with rolling codes. This is most likely a relay attack, the distance from the car to the key is bridged with a repeater. That's harder to solve --- you could measure distance by round trip time, rather than by limiting tx power, but the distances in question are small, and the timing difference between keys at car door and keys at house door isn't very much. Probably the crypto takes longer and may vary more than the difference in transmission time.
Why do we lock our doors when it's proven doors don't stop thieves (putting aside the fact that locking does prevent people from just simply walking away)? Why haven't we improved our security systems? Because people will still buy homes, and insurance covers loss and damage in case of theft.
Without that, we would demand houses that are harder to break into. So it is for cars.
I thought normal replay attacks are solved and the issue here is more to do to forward they key range close to the car to simulate the car.key being close.
That's what I can't easily just solve if not needing a button on the key which defeats the purpose of the said feature
https://www.cnn.com/2023/01/27/business/progressive-state-fa...
Down here in Australia it's been a legal requirement since 2001 that vehicles be sold fitted with immobilisers, and our versions of the Kia and Hyundai models mentioned in the article you link to are not vulnerable to this attack.
The engineering work is already done, it is pure greed on the part of the manufacturer to leave it out.
My car is cheap and doesn't have a wireless key.