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by plorkyeran 818 days ago
The biometric part is incidental. The thing that makes it more secure is that authentication is done by a separate trusted system: the secure enclave, which has its own separate processor, OS, and input device. The primary OS tells the secure enclave to start a security challenge, and then the secure enclave reports success if you scan your finger or nothing if you don't. Malware can't fake this response (at least not without having already pwned your system to an extent that it doesn't need your password), and popping up a fake TouchID dialog doesn't really achieve much of anything. Infecting the secure enclave with malware would let you break everything, but unlike the primary OS it's not designed to run third-party software, so that's significantly harder to do.

FaceID swaps out the fingerprint reader for facial recognition but the actual security features are the same. Yubikeys are the same high-level concept, although the implementation is quite different.
2 comments
cryptoxchange 818 days ago
A yubikey can still be MITM’d with a fake OTP dialog. Anyone who has worked around them for long enough has seen a yubisneeze.

Because of how https://developer.apple.com/documentation/localauthenticatio... works, comparing touchID to yubikeys doesn’t make sense to me.

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jeroenhd 818 days ago
Are these dialogs always rendered on top? I can imagine it wouldn't be too hard to perform some malicious high-risk actions (elevating permissions, disabling protections) and hiding the permission prompt by overlaying something a copy with something that sounds more benign.

You're not leaking credentials there, but if you can get the user to give away the right permissions, you don't need to.

On Android, where apps have the ability to draw on top of other apps (used for things like pop-out players and night light apps) it used to be possible to trick the user into opening their phone's settings and guiding them through a bunch of security options by overlaying a game and letting the taps fall through to the underlying app. This makes me wonder how well-protected macOS is against that kind of attack.

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