fix: Prevent passkey downgrades #40284
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codingllama
commented
Apr 5, 2024
| web1ID := []byte{1, 1, 2} // WebAuthn / MFA | ||
| rk1ID := []byte{1, 1, 3} // WebAuthn / passwordless | ||
| dev1 := &types.MFADevice{ | ||
| u2fID := []byte{1, 1, 1} // U2F |
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Renamed for clarity, nomenclature was still a bit "in flux" when I originally wrote this.
codingllama
commented
Apr 5, 2024
| // registration. | ||
| // Letting users have both allows them to "swap" between key types in the | ||
| // same device. | ||
| if webDev := dev.GetWebauthn(); webDev != nil && webDev.ResidentKey != passwordless { |
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This behavior used to be fine during the "Yubikey era", desirable even, as MFA keys don't require PINs. Yubis are still fine with this, but the recently evolved passkey behavior clearly isn't. :/
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Friendly ping @gabrielcorado @zmb3 ? |
gabrielcorado
approved these changes
Apr 9, 2024
tigrato
approved these changes
Apr 10, 2024
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@codingllama See the table below for backport results.
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This was referenced Apr 10, 2024
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Prevent authenticators from "downgrading" passkeys to "MFA" keys by always adding passkeys to the registration credential exclude list.
Modern authenticators, like Touch ID on Chrome, will always create passkeys regardless of our registration parameters. This can lead to the following situation:
This PR stops 2) from happening: the browser will error with a message in the lines of "You already registered this device".
Related to #39521.
Changelog: Prevent accidental passkey "downgrades" to MFA