Bypass Record
Pre-OS Boot × Google ChromeOS
A publicly-reported instance of Pre-OS Boot bypassing Google ChromeOS, recorded with its original source. Factual record; no assessment of any specific deployment.
Mechanism
The exploit bridges pins 3 and 8 of the flash chip to prevent the Google Security Chip from verifying device hashes during power loss, temporarily bypassing validation checks. This allows disabling read-only (RO) verification via flashrom commands, setting GBB flags, and ultimately unenrolling the device using Sh1mmer and manual TPM/cryptohome commands.
Detection & mitigation
Monitor for physical tampering indicators such as unexpected chassis intrusion events or changes in boot integrity measurements (e.g., TPM PCR values) that deviate from known-good baselines. Mitigate by enforcing full disk encryption, secure boot, and physical security controls to prevent unauthorized hardware access.
This is a record of a publicly-reported event, not an assessment of any specific organization's deployment. Detection and mitigation notes are drawn from the cited source. Where the source is silent, fields are omitted.