Researchers highlight Windows-specific passkey storage risks in new attack analysis

A security analysis published by Ars Technica argues that a recently highlighted attack against passkeys, dubbed Pass-ta-key, is neither novel nor unique to passkeys, despite claims to the contrary. The analysis, written by Dan Goodin, examines how the attack exploits platform-specific behaviors in how passkeys are stored and accessed on Windows devices.

The Pass-ta-key attack, described by researcher Arie Olshtein of Palo Alto Networks, purported to demonstrate a new attack surface in passkeys by showing how malware on a Windows machine could obtain all passkeys stored in the Google Password Manager (GPM) app. The confusion stems from a common misconception: that passkeys are always stored in a Trusted Platform Module (TPM) or similar hardware enclave. In reality, the FIDO 2 specifications do not mandate hardware storage, and most platforms and third-party passkey managers do not use TPMs for passkey storage.

Instead, most platforms outside Windows store passkeys locally on the device. This design decision was made to enable cross-device synchronization, which would be impossible if passkeys were confined to TPMs. Windows, however, presents a unique case: Microsoft recommends TPM storage primarily for enterprises, but most third-party passkey managers on Windows—including Google Password Manager, 1Password, and Dashlane—store passkeys in end-to-end encrypted blobs in the cloud. When a user authenticates, the device retrieves a user or device key from the TPM and presents it to the backend authenticator, which then issues an authentication assertion.

The analysis highlights a key difference in Windows' app privilege model: unlike other platforms, Windows apps often run with full user privileges, and Windows' sandboxing protections do not prevent one app from accessing another's data. This makes it easier for malware on a Windows device to access sensitive data, including passkeys, compared to platforms like macOS, iOS, or Android, where app isolation is stricter by default.

The article emphasizes that the risks demonstrated by Pass-ta-key are not new: any malware running on a fully authenticated device can access sensitive data, regardless of whether passkeys or passwords are used. The core value of passkeys—eliminating shared secrets vulnerable to phishing or server breaches—remains intact, but the analysis underscores that passkeys are not designed to withstand device compromise or physical attacks.