Passkey Compromises & FIDO2 Security Keys: Revoking Rogue Authentication Devices on Google Accounts

The Modern Persistence Vector: Rogue Passkeys

Google’s rollout of Passkeys (FIDO2 / WebAuthn) was designed to eradicate password-based phishing forever. By utilizing public-key cryptography tied to local device biometrics (Touch ID, Face ID, Windows Hello), passkeys cannot be phished over the web.

However, a dangerous persistence technique has emerged: When an attacker gains temporary access to your Google account via session hijacking (cookie theft), the attacker immediately navigates to myaccount.google.com/signinoptions/passkeys and registers their own hardware device as an authorized Passkey.

Even if you successfully reset your password and remove the hacker’s phone number, the attacker’s rogue Passkey remains bound to your account, allowing them to re-enter at will!

Purging Attacker Credentials: The Complete Security Hygiene Sweep

Once access is regained, you must perform an exhaustive cryptographic purge:

• Audit All Registered Passkeys: Navigate to Security -> Passkeys and Security Keys. Delete every passkey whose device model or registration timestamp does not match your personal hardware.
• Invalidate Authenticator Apps: Revoke Google Authenticator bindings and set up a fresh QR code exclusively on an air-gapped device.
• Revoke App Passwords: Check myaccount.google.com/apppasswords. Attackers frequently generate 16-character App Passwords to maintain persistent background IMAP access to your inbox.

For enterprise accounts compromised by rogue persistence hooks, consult our [Google Incident Recovery Specialists](/services/hacked-gmail-google-recovery).