Pass the Passkey: A Novel Attack Surface in Passwordless Authentication

Threat Research Center<br>Threat Research<br>Malware

Malware<br>Pass the Passkey: A Novel Attack Surface in Passwordless Authentication

17 min read

Related ProductsCortexCortex Cloud

By:Arie Olshtein

Published:August 3, 2026

Categories:Malware<br>Threat Research

Tags:Google authenticator<br>Google Chrome<br>Google Cloud<br>Identity<br>Key<br>Passkey<br>Passwordless

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Executive Summary

This article analyzes new attack classes against passwordless authentication, focusing on Google’s synced passkey ecosystem and the Cloud Authenticator used by desktop clients. The attacks demonstrate how malware on a compromised endpoint can misuse onboarding, recovery and device trust workflows to take over passkey-protected accounts. We show how an attacker can authenticate without user interaction, bypass user verification requirements and extract all synced passkey private keys.

After decades of breaches and billions in losses, the attack vectors that defined the era of passwords and shared secrets are finally starting to fade. Passkeys replace passwords and traditional multi-factor authentication (MFA) with public-key cryptography, decreasing entire classes of attacks that have dominated the threat landscape for years.

With no shared secret to steal, reuse or phish, many of an attacker’s most reliable tools are becoming obsolete. This represents a significant disruption for the credential theft market.

Attackers, however, persist. They evolve, and defenders must prepare for a new generation of attacks. As passkeys become widely adopted and scale to billions of accounts, defenders must prepare for new attack surfaces, some of which we disclose in our research.

This article is part 3 in our series examining passkey adoption from a security perspective. If you haven’t read the previous parts, we recommend starting here:

Part 1: The Art of the Invisible Key – Passkey Global Breakthrough

Part 2: Google Authenticator: The Hidden Mechanisms of Passwordless Authentication

Palo Alto Networks customers are better protected from this new attack vector through the following products and services:

Cortex Cloud Identity Security

Idira Threat Detection and Response

Idira Endpoint Privilege Manager

Idira Privilege Access Management

If you think you might have been compromised or have an urgent matter, contact the Unit 42 Incident Response team.

Related Unit 42 Topics<br>Google Authenticator, Cloud, Malware

Setting the Stage

Google’s synced passkey implementation is particularly instructive due to its scale and how it creates a higher standard for private key protection in two critical ways:

Private keys are generated and used within a cloud-enclave isolation environment

Hardware-backed, client-device-bound keys control access to cloud-based cryptographic operations, attesting to the user’s presence on a trusted device

This article builds on the architectural analysis from Part 1 and Part 2 of our previous articles in this series. We now shift from how passkeys are built and deployed to how attackers can misuse them.

We present three novel attacks that enable account takeover of passkey-protected accounts. Each attack challenges a different core assumption of passkey authentication security. When a client authenticates with a passkey, the following is expected:

Users provide explicit consent on the device to verify user presence

For MFA, users must also unlock the device to verify biometric (i.e., something you are) or knowledge-based (i.e., something you know) authentication factors

Passkey private keys cannot be shared or copied

The Google documentation reflects these core assumptions, describing the passkey login process as a secure alternative to passwords (as shown in Figure 1).

Figure 1. Google documentation describes passkeys as requiring device access, device unlock, and non-shareable credentials.<br>Challenging these expectations is a category of attacks we've nicknamed Pass-ta-key. This playful, layered name blends the word passkey and the phrase “pass the key,” with a light nod to the concept of plate of pasta, illustrating how tangled this key implementation can get.

These attacks each expose a different weakness in practice:

Pass-ta-key attack: An attacker takes over an account protected by a Google-synced passkey using malware running on the victim’s device, without requiring privilege escalation, device unlock or user interaction

Silver Pass-ta-key attack: An attacker deceives the Google Cloud Authenticator into believing the victim has unlocked the device with biometrics, leading to full account takeover without using the victim’s device during authentication

Golden Pass-ta-key attack: An attacker can extract all synced passkeys in a form that allows them to be shared or sold on the credential black market

These attacks demonstrate how malware can exploit synced passkeys, even when providers add hardware-backed protections to secure...