The Pixel 4 and 4 XL have barely made it into the hands of reviewers, and a major security flaw has already been discovered: the phone’s new facial recognition will let your face unlock your phone whether you’re awake or not.
Using Face ID or a thumbprint to unlock your smartphone can feel like you’re in a sci-fi movie, but there’s an understandable amount of scepticism around biometrics precisely due to security concerns like this (and others). To prevent exploitation, many manufacturers include measures that check for alertness when using facial recognition to unlock a device, such as scanning for open eyes or requiring the user blink first. Such measures exist on Apple’s products, as well as on previous versions of Android, but the Pixel 4 has no such checks. The phone will let anyone in as long as they can point the phone at its owners, even if they’re dozing, drunk or dead.
— Chris Fox (@thisisFoxx) October 15, 2019
If you’re wondering how such a bug could get past beta testing, the truth is it’s not a bug in the first place, and it wasn’t always like this. Ars Technica points out that earlier models of the Pixel 4 included a “require eyes to be open” option for unlocking your phone with your face, but that setting has been nixed from the final version. Google says a fix is on the way, but it won’t be ready for months.
All is not lost, however; Pixel 4 users have a couple of different avenues for preventing unintended unlocking using their unconscious faces.
The first option is the temporarily disable the biometric unlocks with the “Lockdown” feature. When in lockdown, facial and fingerprint recognition is disabled, and your device will require a pin, pattern, or password the next time you attempt to unlock your phone — though you have to enable this feature in your Pixel 4's system settings in order to use it.
Open the Settings app.
Use the search bar to find “Lockdown.”
Tap the “Lockdown” toggle to enable the feature.
You can then turn on Lockdown by holding down the power key to open the power menu, then tapping “Lockdown.”
The only downside to the Lockdown feature is that it only applies to the next unlock, and must be reapplied each time you wish to turn off biometric unlocks.
If that sounds too tedious, the other option is to just not use the face unlock feature at all, and instead use a pin, pattern, password, or thumbprint to unlock your phone. You can set your preferred unlock method by going to your Settings app, then searching for “screen lock” in the search bar.