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Comment by davidscoville | Hacker News Reader

I believe they logged into coinbase with Google SSO. And then they used my Google Authenticator codes which were cloud synced as the second factor auth method.

A warning to auth engineers: if an account is using a Gmail address, then auth codes from Google Authenticator should not be considered a second factor.

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This isn't something "auth engineers" can control, there's no magic Google Authenticator flag on a 2fa code - it's all HMAC and numbers, you don't know if the code came from Authy, Google Auth, a homebrew code generator, a dongle, etc.

It sounds like we're back to physical Yubikeys as the only secure auth.

Passkeys also solve this even if they’re not hardware backed. He was able to give them a code but wouldn’t have been able to do a passkey handshake for a domain which isn’t Google.com. Plus they’re easier to use and faster.

I don't know about that. If they can hack your Google/iCloud account they can add a new device, sync all your passkeys to that device, then log into all your other accounts.

But they can't hack your Google or iCloud account if it's secured with a passkey, unless they have some other non-phishing means of doing so, which the attacker in this story presumably did not.

I had to reset the 2FA for a domain admin account for Google Apps earlier this year — I'm not sure if my password manager somehow lost the passkey, or if I missed creating one before some deadline. (It's a little-used domain.)

I think I requested the reset with various details, then had to wait 24 hours before continuing.

I feel like a lot of things would benefit from that time delay and, perhaps, an in person check like the notary ID verification AWS used to use.

About a decade ago I had suggested to Google at an identity forum that they embrace a local government/organization model for their hard-landing account recovery process (since it can ultimately devolve to an ID check) by having a mechanism where you can start the account reset process and get something which could be taken to a third party to approve after they do an ID check. As people increasingly depend on things like email accounts for everything there are a constant stream of people who will lose access to their phones but could easily visit a notary, library, DMV, police station, etc. and pass a check against a pre-registered government ID.

How do they do that if you are incapable of giving them a valid authentication code?

I don’t use Google but at least in the Apple world you also get a fairly different prompt for enrolling a new iCloud Keychain device than simply logging in. Obviously that’s not perfect but there is a good argument for not getting people accustomed to hitting okay for both high and low impact challenges using the same prompt.

Seems reasonable if you need to secure five figures or more in crypto.

Exactly. Google created vulnerabilities for the whole industry by introducing cloud synced Authenticator codes.

Similarly the SSO sign in, which I think is much worse. Though arguably Coinbase is at fault for that one.

>A warning to auth engineers: if an account is using a Gmail address, then auth codes from Google Authenticator should not be considered a second factor.

Incredible take. I don't know what's worse here — suggesting gmail address = google authenticator, thinking you can know the source of "auth codes", or the fact this is coming from an auth engineer. I'm switching to handwritten HMACs on paper napkins today.

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