Car theft by relaying signals from wireless keys(technologyreview.com)
technologyreview.com
Car theft by relaying signals from wireless keys
http://www.technologyreview.com/computing/27037/page1/
8 comments
So, the attack starts out with the car stopped, and some sort of equipment to amplify the keyless entry signals to the car and vice versa, so the car thinks the key is within range. The car starts, and they drive away from the amplification system. What happens when the car drives out of range of the key while it is running? Does the engine just turn off, or does it keep going until you press the engine off button?
I wish I had a car to experiment with... but on the other hand I'll stick with the old fashioned keys, even if those are rather easy to get past too.
> What happens when the car drives out of range of the key while it is running? Does the engine just turn off[...]?
Would be nasty. Imagine the car key running out of battery on the motorway.
Would be nasty. Imagine the car key running out of battery on the motorway.
The key doesn't have a battery. It's usually RFID.
On my Lexus it's both active and passive RFID. If you start the car and the key is 'active', you have to keep it in the cabin, or the car starts complaining (I've not been brave enough to drive with it not in there...).
If you start the car with the key as passive (ie: dead battery - you have to hold it on the ignition button to be detected), it recognizes the difference and doesn't complain.
If you start the car with the key as passive (ie: dead battery - you have to hold it on the ignition button to be detected), it recognizes the difference and doesn't complain.
Just because it's "active" doesn't mean the FOB needs a battery for the RFID to work. The car could periodically check for the key.
If your RFID required a battery, and required that it constantly be on, then the battery would need to be replaced often. Couple this with your car potentially shutting off in the middle of the highway and you've got a very unsafe car.
I know for certain that VW keys do not need the battery for the RFID to work. The battery is only used for remote lock/unlock. Perhaps other cars are different, but I'd consider that a design flaw.
edit: forgot to mention that my VW does not even have physical locks except for the glovebox. A dead rfid battery, if it had one, would mean i was stranded. I'm actually not sure what happens if my car battery dies while the car is locked.
If your RFID required a battery, and required that it constantly be on, then the battery would need to be replaced often. Couple this with your car potentially shutting off in the middle of the highway and you've got a very unsafe car.
I know for certain that VW keys do not need the battery for the RFID to work. The battery is only used for remote lock/unlock. Perhaps other cars are different, but I'd consider that a design flaw.
edit: forgot to mention that my VW does not even have physical locks except for the glovebox. A dead rfid battery, if it had one, would mean i was stranded. I'm actually not sure what happens if my car battery dies while the car is locked.
The fob battery does die fairly often (replace it once/twice a year?).
My car has no visible physical locks - there's a small notch under the drivers door handle you can pop off a piece of the handle using the fob, and then there is a physical lock you can get into the car with (no way to open the trunk until you turn the car on).
I've had to do this a few times :)
Like I said, you can still use the key to start the car, but if the battery is dead, you have to hold it up to the start button.
My car has no visible physical locks - there's a small notch under the drivers door handle you can pop off a piece of the handle using the fob, and then there is a physical lock you can get into the car with (no way to open the trunk until you turn the car on).
I've had to do this a few times :)
Like I said, you can still use the key to start the car, but if the battery is dead, you have to hold it up to the start button.
The car keeps running, or at least the Prius does.
This comes after e.g. the KeeLoq debacle: see http://dblp.mpi-inf.mpg.de/dblp-mirror/index.php?query=keelo.... Summary: cryptographically securing remote car keys/garage openers is an improvement (older products just broadcast the password), but badly implementing outdated custom algorithms is... not as useful as the car industry seems to hope.
I'll stick with "real" keys for a while yet.
I'll stick with "real" keys for a while yet.
Do they still sell new cars with traditional keys?
If you look at e.g. http://www.bmw.com/com/en/newvehicles/3series/sedan/2008/all... and click the second icon under the image, "comfort access" - this seems to be optional. And we're not talking a thirty-year old Skoda here.
Ah. I was just thinking of keyless entry (which is definitely standard on that BMW), rather than the keyless start.
This is a protocol flaw. The design assumes that proximity (signal) implies authorization, but the researcher proved this isn't always the case. The protocol should at least provide assurance that authorization really comes from the person who has the key fob. Old style physical keys do that, and so do key fobs with buttons.
I'm confused. The article seems to be about the ignition key mechanism, yet claims no trace of forced entry, which is unrelated. Surely you need to unlock the car doors and disable the alarm/immobiliser before you can drive off with it? Or are we assuming people leave their cars unlocked?
Also, once you've driven the car away, you'll have to find another way of starting it in future; relaying still needs some kind of physical access (albeit at 8 metres distance) to the original key.
(I'm aware of broken crypto in some wireless keys, which is purely an implementation issue - you can make these secure. That's not what this article is about. Quote: The attack works no matter what cryptography and protocols the key and car use to communicate with each other.)
Also, once you've driven the car away, you'll have to find another way of starting it in future; relaying still needs some kind of physical access (albeit at 8 metres distance) to the original key.
(I'm aware of broken crypto in some wireless keys, which is purely an implementation issue - you can make these secure. That's not what this article is about. Quote: The attack works no matter what cryptography and protocols the key and car use to communicate with each other.)
The "keys" in question are the ones that magically unlock the car when you are "close." The attack is a "man in the middle" attack that basically fools the car into thinking the owner is nearby when he isn't, so the car unlocks and enables the ignition.
Apparently, once the ignition is enabled, you can drive off without needing the key "nearby" (interesting experiment, I'll have to try that next time I get a "keyless entry" rental). Once you can drive off, the car is pwned - you can strip it for parts (chop shop) or fully defeat the key/ignition security away from prying eyes.
Apparently, once the ignition is enabled, you can drive off without needing the key "nearby" (interesting experiment, I'll have to try that next time I get a "keyless entry" rental). Once you can drive off, the car is pwned - you can strip it for parts (chop shop) or fully defeat the key/ignition security away from prying eyes.
Oh, I see. All the wireless car keys I've seen need a button to be pressed to unlock the driver's door.[1] I'll have to watch out for buttonless keys when buying a car next, it seems a pretty unsafe concept in itself, e.g. loitering hijacker getting in the car before you do/with you, etc.
[1] You usually need to press the button a second time to unlock the remaining doors. There's also often a separate button to independently unlock the boot. A typical procedure is therefore: open boot with the relevant button, put shopping inside, close boot, take trolley back to the stand, walk back to the car, unlock only the driver's side, get in, lock door with button from the inside, drive off.
[1] You usually need to press the button a second time to unlock the remaining doors. There's also often a separate button to independently unlock the boot. A typical procedure is therefore: open boot with the relevant button, put shopping inside, close boot, take trolley back to the stand, walk back to the car, unlock only the driver's side, get in, lock door with button from the inside, drive off.
In my car you need the RF signal from the keyfob to be nearby to open/start it. Once the engine is running, it will keep running until you turn it off, or it runs out of gas, even if the keyfob is not present.
If you turn the ignition off and it can't "see" the key, it will give you a warning message on the display cluster and you have something like 20 seconds to re-start the car before you're locked out.
If you turn the ignition off and it can't "see" the key, it will give you a warning message on the display cluster and you have something like 20 seconds to re-start the car before you're locked out.
Some cars, like my VW, require the key fob to be in the car or the immobilizer shuts the car off after a very short distance. I believe all VW cars have this now, even the ones without keyless entry/ignition. This of course just slightly complicates the hack.
On my parents Prius there is some logic involved in weather or not the doors unlock automatically. If you open the driver's door it will unlock automatically, the other doors will be locked. If you open a passenger door all doors on the car are unlocked. Either way it is always possible to unlock at least one door with out hitting a button. The car can start as long as it can see the key and will keep running even after the key has been removed.
This could be fixed with an on/off button on the fobs, no? It takes some of the convenience out of the fob, but it would still be somewhat easier than fiddling around with a physical key, though quite a bit of convenience is lost.
Another way would be to attach the key to something like a smartphone. The car finds it location via GPS and stores it on a server somewhere. If the fob receives a signal from what it thinks is the car, it asks the smartphone to confirm its location is near the car's location. The fall-back in case the smartphone is out of battery or the car did not post its location would be this vulnerable method where the fob simply responds if it has received the message from the car.
Another way would be to attach the key to something like a smartphone. The car finds it location via GPS and stores it on a server somewhere. If the fob receives a signal from what it thinks is the car, it asks the smartphone to confirm its location is near the car's location. The fall-back in case the smartphone is out of battery or the car did not post its location would be this vulnerable method where the fob simply responds if it has received the message from the car.
Surely car design/manufacture is much harder than implementing proven crypto? The mind boggles. Crypto is a solved problem as far as protecting passwords goes. How can such huge companies continue to get it wrong?
If I made cars, I'd make sure I'd solved this problem on my products, then buy some TV adverts showing thieves in carparks bumping other manufacturers locks wirelessly with ease. Perhaps backed by graceful classical music. Try and make it look like the advert was bought by my rivals and aimed at car thieves.
Although that might be asking for it...
If I made cars, I'd make sure I'd solved this problem on my products, then buy some TV adverts showing thieves in carparks bumping other manufacturers locks wirelessly with ease. Perhaps backed by graceful classical music. Try and make it look like the advert was bought by my rivals and aimed at car thieves.
Although that might be asking for it...
"Broken" is correct, but arguably too strong of a term. It is a man-in-the-middle attack, where the "man" in the middle is relaying the signals without modification and with an extremely short delay between the "key" and the car.
The article notes that their system specifically delays the challenge/response by nanoseconds vs. milliseconds by staying in the analog realm because doing a A/D -> Tx -> Rx -> D/A sequence added too much delay.
This implies either the car security system either measures the challenge/response delay or could measure it in which case this MitM attack still will work since attack's nSec delays will be very difficult to detect.
Most relay attacks require the signals to be converted from analog to digital and back, which takes time. The researchers were able to keep the signals in analog format, which reduced their delay from microseconds to nanoseconds and made their attack more difficult to detect.
The article notes that their system specifically delays the challenge/response by nanoseconds vs. milliseconds by staying in the analog realm because doing a A/D -> Tx -> Rx -> D/A sequence added too much delay.
This implies either the car security system either measures the challenge/response delay or could measure it in which case this MitM attack still will work since attack's nSec delays will be very difficult to detect.
Most relay attacks require the signals to be converted from analog to digital and back, which takes time. The researchers were able to keep the signals in analog format, which reduced their delay from microseconds to nanoseconds and made their attack more difficult to detect.
> Surely car design/manufacture is much harder than implementing proven crypto?
No crypto is broken in this scenario.
No crypto is broken in this scenario.
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Keeping track of your secrets is as essential a part of a crypto implementation as the algorithm used. As I understand it, they could have used something like this: https://secure.wikimedia.org/wikipedia/en/wiki/Socialist_mil...
EDIT: I understand now, having read more carefully, about how this particular MITM attack works. Nasty. The only solution would seem to be to give up some convenience.
EDIT: I understand now, having read more carefully, about how this particular MITM attack works. Nasty. The only solution would seem to be to give up some convenience.
I bet a lot of wireless keys are insecure because someone's pointy-haired boss told an engineer it would be cheaper to implement the device by leaving out the challenge-response.
Untold Billions are probably lost every year by someone in charge ignoring something learned by freshmen undergrads.
Untold Billions are probably lost every year by someone in charge ignoring something learned by freshmen undergrads.
The described attack would quite happily work even if there was a challenge-response system. It works by effectively extending the range of the key, automatically unlocking the car using the key even though the key is so far away the owner won't notice you stealing the car.
Sadly but this future already is in Russia for a long time. This google translated article [1] from 2006 is about different code-grabbers. There is different car insurance price depending do you have additional not so easy breakable wireless alarm installed.
[1] http://translate.google.ru/translate?js=n&prev=_t&hl...