Google has paid out $70,000 to a security researcher for privately reporting an “accidental” security bug that allowed anyone to unlock Google Pixel phones without knowing its passcode.

Android lock screens let users set a numerical passcode, password or a pattern to protect their phone’s data, or these days a fingerprint or face print. Your phone’s SIM card might also have a separate PIN code set to block a thief from ejecting and physically stealing your phone number. But SIM cards have an additional personal unlocking code, or PUK, to reset the SIM card if the user incorrectly enters the PIN code more than three times. PUK codes are fairly easy for device owners to obtain, often printed on the SIM card packaging or directly from the cell carrier’s customer service.

Schütz found that the bug meant that entering a SIM card’s PUK code was enough to trick his fully patched Pixel 6 phone, and his older Pixel 5, into unlocking his phone and data, without ever visually displaying the lock screen. He warned that other Android devices might also be vulnerable.

Since a malicious actor could bring their own SIM card and its corresponding PUK code, only physical access to the phone is required, he said. “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,” said Schütz.

A simple Android lock screen bypass bug landed a researcher $70,000 by Zack Whittaker originally published on TechCrunch