Google has fixed a high-severity security bug, tracked as CVE-2022-20465, affecting all Pixel smartphones which when exploited can let attackers to unlock the devices.
The Google Pixel Lock Screen Bypass was reported by security researcher David Schütz and he was awarded $70,000 for this flaw.
According to a post published by Schütz, the issue allowed an attacker with physical access to bypass the lock screen protections (fingerprint, PIN, etc.) and gain complete access to the user’s device. The vulnerability might affect other Android vendors as well.
The expert discovered how to unlock a Pixel phone using a PIN-locked SIM card and knowing its PUK code.
He reported the vulnerability in June 2022 and Google fixed it the release of Android update for November 2022.
On noticing a strange behavior of his mobile, Schütz rebooted the phone, putting in the incorrect PIN 3 times, entering the PUK, and choosing a new PIN. He noticed that the device went to the “Pixel is starting…” state.
He made further tests and discovered that is possible to bypass lock screen protections with the following sequence of actions:
- Supply the wrong fingerprint three times on the locked device, this causes to disable biometric authentication.
- Hot swap the SIM tray using an attacker-controlled SIM and reset the PIN.
- Enter the incorrect SIM PIN three times, causing the lock of the SIM card.
- In order to unlock the device, it is requested to enter the SIM’s Personal Unlocking Key (PUK) code.
- Enter a new PIN code for the attacker-controlled SIM
- The devices unlocks.
Schütz explained that the attacker could just swap the SIM in the victim’s device, and perform the exploit with a SIM card that had a PIN lock and for which the attacker knew the correct PUK code.
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