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I think the most annoying part of this is that you cannot just replace a YubiKey. Regardless of whether you're using passkeys or the non-discoverable ones, you

I think the most annoying part of this is that you cannot just replace a YubiKey. Regardless of whether you're using passkeys or the non-discoverable ones, you need to manually go through each account and replace the YubiKey with a non-vulnerable key before decommissioning this one. And then there is the non-discoverable part. I don't remember where I've used my YubiKey in the past. Also, on the Ars article [0] there is mention of a PIN: > YubiKeys provide optional user authentication protections, including the requirement for a user-supplied PIN code or a fingerprint or face scan. This is not a YubiKey thing, but a FIDO thing [1]. [0]: https://arstechnica.com/security/2024/09/yubikeys-are-vulnerable-to-cloning-attacks-thanks-to-newly-discovered-side-channel/ https://arstechnica.com/security/2024/09/yubikeys-are-vulner... [1]: https://new.reddit.com/r/yubikey/comments/12bv4sv/fido_pin_sometimes_not_required/ https://new.reddit.com/r/yubikey/comments/12bv4sv/fido_pin_s...

webstrand 2y ago
I've always hated that I couldn't clone or backup my personal yubikey. It's one of the reasons I've avoided using it everywhere.
- kyrra 2y ago
  I mean, that's the security story around it. You solve this and buying multiple yubikeys. Google and others support multiple keys, which gives you the backup story (I have 4 keys in various places).
  - jzig 2y ago
    You register 4 keys on each website?
    - fragmede 2y ago
      I mean, not all at once, but (I only have 3) there's the one when I bought a new laptop in 2019 which I setup when I got that laptop and became the old one when I got a new laptop in 2021 and setup a second one. And then the third one is a backup key I made at some point and is stored offsite in case I/my house gets robbed/burgled or my place burns down in a fire. It's inconvenient, sure, but it's more convenient than my bank accounts that are accessible online being cleaned out.
    - michaelt 2y ago
      You register multiple keys on a handful of critically important websites. Password manager. Primary e-mail account. DNS provider. Other than that, it's rarely supported and rarely worth the hassle when it is.
      - brendoelfrendo 2y ago
        It is really annoying that more sites don't support multiple security keys, though. As far as I can tell, it's not encouraged by the FIDO Alliance and I can't think of a good technical reason for it.
        vel0city 2y ago
        The vast majority of sites I've used Yubikeys for have supported multiple. About the only one that I use which still doesn't to my knowledge is Paypal.
        brendoelfrendo 2y ago
        Maybe I'm out of date, then! I don't enroll new keys very often. Paypal is a great example of a service that I would like to support multiple keys, though, so it's disappointing that they still only support one.
        fullstop 2y ago
        I forget which financial institution I was using at the time, but they explicitly only supported one key. That is, you add a new one and the old one is expunged. Banks are so slow with this sort of thing, and still require SMS as a fallback option.
        beezle 2y ago
        How often do you check to see that those other/backup keys are still secure? This attack becomes easier if the attacker knows of the secondary key(s) location and because of disuse they aren't even necessary to replace.
    - DANmode 2y ago
      If you have a hardware key setup for anything you want sustainably operated in the future, you register at least two keys, and when one fails or is lost, you pull the emergency backup out of a safe and register new one(s).
      - nicolas_17 2y ago
        You also have to pull the emergency backup out of the safe when signing up for a new thing. It's highly inconvenient.
        throwaway48476 2y ago
        Still more convenient than getting locked out.
        drdaeman 2y ago
        It becomes questionable if you’re halfway across the world from your safe.
        lxgr 2y ago
        True, but what's even more convenient than that is to just not use hardware authenticators for anything but the most important accounts/sites, and e.g. use syncing credentials (as provided by many password managers, Google, and Apple). The fraction of people willing to regularly schedule enroll-o-ramas at each of their accounts and each of their backup key locations is probably smaller than a percent of all potential WebAuthN users.
  - deleted 2y ago
    [deleted]
  - lxgr 2y ago
    There's no fundamental reason it needs to be this difficult. Yubico or really any other manufacturer could totally e.g. release "Yubikey pairs", both a stateless CTAP2 implementation with the same root secret, that would correspondingly work at the same sites without having to synchronize anything. The reason they probably don't is that their entire trust model heavily depends on the perception that nobody, including the manufacturer, has a "reserve key" to any given Yubikey, even though of course the absence of such "linked keys" doesn't demonstrate the absence of any such backdoor. To be clear, I don't have any reason to believe Yubico does this, but it would probably be a harder story to tell, marketing-wise, if they sometimes selectively did, even if it's for a valid use case.
    - filleokus 2y ago
      I mean you could also design keys to be synchronisable by the user. Generate a key-pair inside of key (2), transfer the public key from (2) to (1). Encrypt the the root key inside of (1) with the public key, transfer it over to (2). (Or just allow the user to generate the root key outside of the device and insert it) I honestly think the interest from customers is just too low. I would bet the majority of Yubico's customers are enterprises where this is not really an issue for most use cases. If you loose your key used for Entra ID / SSO, just go to IT support and get a new one enrolled to your account. Much cheaper than having synchronised hot spares (at 30-50 USD a pop) for thousands of employees.
      - KAMSPioneer 2y ago
        But what stops Mallory from simply using this sync method to sync your private key to her Yubikey? I mean, look at the kerfuffle that's been kicked up by this vulnerability, and a key-sharing scheme like the above is much easier to exploit. (The second idea seems better assuming the user nukes the private key once the import is done. Otherwise the weakest link in the security chain will continue to be the opsec you practice with the private key file, in which case why spend the money on the Yubikey?)
        filleokus 2y ago
- thadt 2y ago
  Good news then, since the article is discussing the discovery of that exact feature.
mimimi31 2y ago
>I don't remember where I've used my YubiKey in the past. I track this in my password manager. Accounts where the YubiKey is enrolled are tagged "YubiKey (FIDO)".
- dotancohen 2y ago
  This would probably be a good place to suggest to others here to track which accounts you've logged into via Google or other social media oath. I just had to log into stack overflow for the first time in years, and did not remember what I used to previously log in. Once I figured it out that information went into Keepass too.
  - shepherdjerred 2y ago
    1Password has this functionality and it's excellent.
  - pjot 2y ago
    Just fyi, Google lists sites you’ve used to “sign in with Google” in your account setting page. Apple and GitHub have this as well.
    - dotancohen 2y ago
      Thank you, I should review that.
    - throwaway48476 2y ago
      You should assume Google, GitHub, and Apple are hostile and try to limit your blast radius. If you have an account problem they have no customer service to help you.
      - hamburglar 2y ago
        Yes, this is exactly why I won’t use these federated identity features of platforms like this. I have a reasonable amount of trust that they are mostly secure, but I have zero trust that they will be helpful if I ever have account troubles. What I don’t need is to have Google (etc) auth problems cascade down to every other account I own.
Arch-TK 2y ago
If you're using a yubikey solely for its PGP key stuff and you have a backup of the key or have a key hierarchy then replacing a yubikey is pretty trivial. (I know because it's my specific usecase.)
- lima 2y ago
  Only if the key is generated off-key
  - Arch-TK 2y ago
    I meant to imply that with this statement: > and you have a backup of the key
xaduha 2y ago
> I don't remember where I've used my YubiKey in the past. I've yet to encounter a site that allows to enroll a FIDO device without setting up some other form of 2FA and for me it's TOTP which are kept in the app.
- girvo 2y ago
  Yeah I stick to TOTP for the most part which means the YubiCo app has the list. I always enrol two keys though, one back up and one active.
cvhc 2y ago
Another side. I always worry more about being locked out by 2FA (a main use case of non-discoverable FIDO keys) as a consequence of lost/retired-then-forgotten keys. This happened once when the US custom detained my electronics, including a Yubikey. Later I managed to recover many accounts that accept email for 2FA or as the ultimate auth factor (i.e., password/2FA reset). But a few, including AWS, doesn't allow that. Many websites encourage you to enroll 2FA without clarifying the alternative factors and the consequence of lost access.
- berdario 2y ago
  > the US custom detained my electronics, including a Yubikey Can you elaborate on what happened? I know that it's theoretically possible, but I thought that: 1- They would potentially detain only devices that they can extract information out of (even if encrypted), like a laptop or some hard disk... Yubikey (at least the old U2F-only ones) don't have anything that you can extract 2- They would eventually return the device to you (unless guilty of some national security violation?) Am I mistaken on both counts?
  - vanchor3 2y ago
    If they just seize it, it will typically be returned at some point. If they decide it's subject to forfeiture, it is now their property. You can contest this with the forfeiture department but I guess if they decide the item is guilty of a crime or other excuses to keep it there's nothing you can do.
    - plagiarist 2y ago
      That's right. It will be United States v. Some Person's Yubikey. And you can hire it a lawyer if you want, because they will NOT give it a public defender. Massive violation of Constitutional rights if you ask me.
  - cvhc 2y ago
    For 1, tbh I don't know the rules. technically it was a regular model and can store some data. Or maybe they simply suspected it's a usb disk. And 2 was true. But it was after weeks, and of course I didn't wait until then to reset my account credentials.
dboreham 2y ago
Sounds like functionality you could implement on a blockchain...
- lxgr 2y ago
  You can implement most things on a blockchain, but only very rarely does that make any sense.
DANmode 2y ago
> you cannot just replace a YubiKey. How would this work?
duxup 2y ago
Everything about security / auth sucks in this age. Each time I go down this path with either work or personal stuff it's just people changing passwords all the time / having to re-login all the time ... there's no happy path without a huge hassle.
i80and 2y ago
For sites that use a resident webauthn token like GitHub, you can list the known sites on the key. The UX for all this is not where it should be, however.
- vaylian 2y ago
  Are you sure that GitHub uses resident keys? I'm fairly sure they use non-resident keys.
  - bigfatkitten 2y ago
    They do now, but they didn't in the past.
    - vaylian 2y ago
      Any idea why this was changed? The big advantage of non-residential keys is that they do not take up any space on the Fido token and thus you can have an unlimited number of them.
      - bigfatkitten 2y ago
        They wanted discoverable credentials to enable the magic username-less "sign in with passkey" auth flow.
        vaylian 2y ago
        I really couldn't care less about that. But I do care about the limited space on my fido token.
        bigfatkitten 2y ago
        I've used five RK slots out of 25 available on my daily driver keys. Three of those are for SSO providers that provide access to the majority of the other apps I use. I opt in to "sign in with Google" etc wherever I can. I don't see this impacting me personally anytime soon, but that might change when more sites start insisting on rolling their own RKs. Hopefully future Yubikey models will ship with more flash, enabling many more RKs if you so desire.

webstrand 2y ago

I've always hated that I couldn't clone or backup my personal yubikey. It's one of the reasons I've avoided using it everywhere.

kyrra 2y ago
I mean, that's the security story around it. You solve this and buying multiple yubikeys. Google and others support multiple keys, which gives you the backup story (I have 4 keys in various places).
- jzig 2y ago
  You register 4 keys on each website?
  - fragmede 2y ago
    I mean, not all at once, but (I only have 3) there's the one when I bought a new laptop in 2019 which I setup when I got that laptop and became the old one when I got a new laptop in 2021 and setup a second one. And then the third one is a backup key I made at some point and is stored offsite in case I/my house gets robbed/burgled or my place burns down in a fire. It's inconvenient, sure, but it's more convenient than my bank accounts that are accessible online being cleaned out.
  - michaelt 2y ago
    You register multiple keys on a handful of critically important websites. Password manager. Primary e-mail account. DNS provider. Other than that, it's rarely supported and rarely worth the hassle when it is.
    - brendoelfrendo 2y ago
      It is really annoying that more sites don't support multiple security keys, though. As far as I can tell, it's not encouraged by the FIDO Alliance and I can't think of a good technical reason for it.
      - vel0city 2y ago
        The vast majority of sites I've used Yubikeys for have supported multiple. About the only one that I use which still doesn't to my knowledge is Paypal.
        brendoelfrendo 2y ago
        Maybe I'm out of date, then! I don't enroll new keys very often. Paypal is a great example of a service that I would like to support multiple keys, though, so it's disappointing that they still only support one.
      - fullstop 2y ago
        I forget which financial institution I was using at the time, but they explicitly only supported one key. That is, you add a new one and the old one is expunged. Banks are so slow with this sort of thing, and still require SMS as a fallback option.
      - beezle 2y ago
        How often do you check to see that those other/backup keys are still secure? This attack becomes easier if the attacker knows of the secondary key(s) location and because of disuse they aren't even necessary to replace.
  - DANmode 2y ago
    If you have a hardware key setup for anything you want sustainably operated in the future, you register at least two keys, and when one fails or is lost, you pull the emergency backup out of a safe and register new one(s).
    - nicolas_17 2y ago
      You also have to pull the emergency backup out of the safe when signing up for a new thing. It's highly inconvenient.
      - throwaway48476 2y ago
        Still more convenient than getting locked out.
        drdaeman 2y ago
        It becomes questionable if you’re halfway across the world from your safe.
        lxgr 2y ago
        True, but what's even more convenient than that is to just not use hardware authenticators for anything but the most important accounts/sites, and e.g. use syncing credentials (as provided by many password managers, Google, and Apple). The fraction of people willing to regularly schedule enroll-o-ramas at each of their accounts and each of their backup key locations is probably smaller than a percent of all potential WebAuthN users.
- deleted 2y ago
  [deleted]
- lxgr 2y ago
  There's no fundamental reason it needs to be this difficult. Yubico or really any other manufacturer could totally e.g. release "Yubikey pairs", both a stateless CTAP2 implementation with the same root secret, that would correspondingly work at the same sites without having to synchronize anything. The reason they probably don't is that their entire trust model heavily depends on the perception that nobody, including the manufacturer, has a "reserve key" to any given Yubikey, even though of course the absence of such "linked keys" doesn't demonstrate the absence of any such backdoor. To be clear, I don't have any reason to believe Yubico does this, but it would probably be a harder story to tell, marketing-wise, if they sometimes selectively did, even if it's for a valid use case.
  - filleokus 2y ago
    I mean you could also design keys to be synchronisable by the user. Generate a key-pair inside of key (2), transfer the public key from (2) to (1). Encrypt the the root key inside of (1) with the public key, transfer it over to (2). (Or just allow the user to generate the root key outside of the device and insert it) I honestly think the interest from customers is just too low. I would bet the majority of Yubico's customers are enterprises where this is not really an issue for most use cases. If you loose your key used for Entra ID / SSO, just go to IT support and get a new one enrolled to your account. Much cheaper than having synchronised hot spares (at 30-50 USD a pop) for thousands of employees.
    - KAMSPioneer 2y ago
      But what stops Mallory from simply using this sync method to sync your private key to her Yubikey? I mean, look at the kerfuffle that's been kicked up by this vulnerability, and a key-sharing scheme like the above is much easier to exploit. (The second idea seems better assuming the user nukes the private key once the import is done. Otherwise the weakest link in the security chain will continue to be the opsec you practice with the private key file, in which case why spend the money on the Yubikey?)
      - filleokus 2y ago
thadt 2y ago
Good news then, since the article is discussing the discovery of that exact feature.

mimimi31 2y ago

>I don't remember where I've used my YubiKey in the past. I track this in my password manager. Accounts where the YubiKey is enrolled are tagged "YubiKey (FIDO)".

dotancohen 2y ago
This would probably be a good place to suggest to others here to track which accounts you've logged into via Google or other social media oath. I just had to log into stack overflow for the first time in years, and did not remember what I used to previously log in. Once I figured it out that information went into Keepass too.
- shepherdjerred 2y ago
  1Password has this functionality and it's excellent.
- pjot 2y ago
  Just fyi, Google lists sites you’ve used to “sign in with Google” in your account setting page. Apple and GitHub have this as well.
  - dotancohen 2y ago
    Thank you, I should review that.
  - throwaway48476 2y ago
    You should assume Google, GitHub, and Apple are hostile and try to limit your blast radius. If you have an account problem they have no customer service to help you.
    - hamburglar 2y ago
      Yes, this is exactly why I won’t use these federated identity features of platforms like this. I have a reasonable amount of trust that they are mostly secure, but I have zero trust that they will be helpful if I ever have account troubles. What I don’t need is to have Google (etc) auth problems cascade down to every other account I own.

Arch-TK 2y ago

If you're using a yubikey solely for its PGP key stuff and you have a backup of the key or have a key hierarchy then replacing a yubikey is pretty trivial. (I know because it's my specific usecase.)

lima 2y ago
Only if the key is generated off-key
- Arch-TK 2y ago
  I meant to imply that with this statement: > and you have a backup of the key

xaduha 2y ago

> I don't remember where I've used my YubiKey in the past. I've yet to encounter a site that allows to enroll a FIDO device without setting up some other form of 2FA and for me it's TOTP which are kept in the app.

girvo 2y ago
Yeah I stick to TOTP for the most part which means the YubiCo app has the list. I always enrol two keys though, one back up and one active.

cvhc 2y ago

Another side. I always worry more about being locked out by 2FA (a main use case of non-discoverable FIDO keys) as a consequence of lost/retired-then-forgotten keys. This happened once when the US custom detained my electronics, including a Yubikey. Later I managed to recover many accounts that accept email for 2FA or as the ultimate auth factor (i.e., password/2FA reset). But a few, including AWS, doesn't allow that. Many websites encourage you to enroll 2FA without clarifying the alternative factors and the consequence of lost access.

berdario 2y ago
> the US custom detained my electronics, including a Yubikey Can you elaborate on what happened? I know that it's theoretically possible, but I thought that: 1- They would potentially detain only devices that they can extract information out of (even if encrypted), like a laptop or some hard disk... Yubikey (at least the old U2F-only ones) don't have anything that you can extract 2- They would eventually return the device to you (unless guilty of some national security violation?) Am I mistaken on both counts?
- vanchor3 2y ago
  If they just seize it, it will typically be returned at some point. If they decide it's subject to forfeiture, it is now their property. You can contest this with the forfeiture department but I guess if they decide the item is guilty of a crime or other excuses to keep it there's nothing you can do.
  - plagiarist 2y ago
    That's right. It will be United States v. Some Person's Yubikey. And you can hire it a lawyer if you want, because they will NOT give it a public defender. Massive violation of Constitutional rights if you ask me.
- cvhc 2y ago
  For 1, tbh I don't know the rules. technically it was a regular model and can store some data. Or maybe they simply suspected it's a usb disk. And 2 was true. But it was after weeks, and of course I didn't wait until then to reset my account credentials.

dboreham 2y ago

Sounds like functionality you could implement on a blockchain...

lxgr 2y ago
You can implement most things on a blockchain, but only very rarely does that make any sense.

DANmode 2y ago

> you cannot just replace a YubiKey. How would this work?

duxup 2y ago

Everything about security / auth sucks in this age. Each time I go down this path with either work or personal stuff it's just people changing passwords all the time / having to re-login all the time ... there's no happy path without a huge hassle.

i80and 2y ago

For sites that use a resident webauthn token like GitHub, you can list the known sites on the key. The UX for all this is not where it should be, however.

vaylian 2y ago
Are you sure that GitHub uses resident keys? I'm fairly sure they use non-resident keys.
- bigfatkitten 2y ago
  They do now, but they didn't in the past.
  - vaylian 2y ago
    Any idea why this was changed? The big advantage of non-residential keys is that they do not take up any space on the Fido token and thus you can have an unlimited number of them.
    - bigfatkitten 2y ago
      They wanted discoverable credentials to enable the magic username-less "sign in with passkey" auth flow.
      - vaylian 2y ago
        I really couldn't care less about that. But I do care about the limited space on my fido token.
        bigfatkitten 2y ago
        I've used five RK slots out of 25 available on my daily driver keys. Three of those are for SSO providers that provide access to the majority of the other apps I use. I opt in to "sign in with Google" etc wherever I can. I don't see this impacting me personally anytime soon, but that might change when more sites start insisting on rolling their own RKs. Hopefully future Yubikey models will ship with more flash, enabling many more RKs if you so desire.