Google’s synchronized passkeys can be stolen in ‘Pass‑ta‑key’ attacks

Passkeys were supposed to make stolen passwords a thing of the past. No password to phish, no secret to reuse, and no string of characters sitting in a database waiting to be leaked. Over time, it’s thought that passkeys will replace passwords entirely. But what happens when malware steals the master key? Researchers have found a way for malware to hijack passkey-protected accounts through Google Password Manager, highlighting an important exception: passkeys can be very secure but the software surrounding them still has weaknesses. What are passkeys? Passkeys are a password replacement based on public‑key cryptography. Instead of a secret you remember and type, each account gets a key pair where the private key never leaves your devices, and the website only ever sees the public key and signed challenges. Because there’s nothing reusable to phish or reuse on another site, passkeys are marketed as “phishing‑resistant” and safer than passwords stored in a browser or password manager. By the end of 2024 Google reportedly said that 800 million Google accounts used passkeys. Passkeys have a major advantage over passwords: there is nothing useful for a phishing site to steal. A passkey is also tied to the website it was created for, making it much harder to trick into authenticating to the wrong domain. The other significant difference is that if malware steals a password vault, an attacker still often needs to get past a second factor on another device, such as an authenticator app on your phone, before they fully own the account. With passkeys, many services relying on them simply trust the passkey assertion, and in some cases even trust a single “user verified” flag without confirming whether a real biometric or PIN event occurred. Malware comes into play The researchers, however, started with a malware infected Windows computer and came up with three possible attack scenarios to steal Google synchronized passkeys. Google Password Manager can synchronize passkeys between devices, which is convenient since you don’t want to register a new passkey every time you buy a new computer. But it also opens them up to abuse. From bad to worse the attacks are: Pass‑ta‑key : malware on the victim’s computer silently asks Chrome and Google’s cloud to create a valid passkey login, no biometric or PIN prompt needed. Silver Pass‑ta‑key : malware abuses device re‑enrollment to register its own user‑verification key, then logs in as the victim from the attacker’s machine without touching the victim’s device. Golden Pass‑ta‑key : Malware extracts Google’s security domain secret (the master encryption key), decrypts all synced passkeys, and can reuse them anywhere, even after losing access to the original device. How to stay safe The researchers urge services to stop blindly trusting the user verification flag and to properly validate that a real User Verified event occurred before granting access. Google, in turn, is encouraged to harden device registration and recovery, and verify that new devices and keys are backed by genuine hardware rather than accepting them at face value. For end users, passkeys still offer strong protection against classic phishing websites and credential stuffing attacks based on reused passwords. The weak point highlighted here is not so much the concept of passkeys, but the way they’re implemented, synchronized, and trusted without enough verification on the server side. Until vendors close these gaps, basic anti‑malware hygiene remains critical. The best ways to prevent malware from using your passkeys are: Keep on top of updates: make sure your systems and software are patched as soon as you can. Use up-to-date real-time anti-malware protection . Treat unexpected attachments or links as suspicious until proven innocent. From reporting threats to removing them. Cybersecurity risks should never spread beyond a headline. Keep threats off your devices by downloading Malwarebytes today . About the author Was a Microsoft MVP in consumer security for 12 years running. Can speak four languages. Smells of rich mahogany and leather-bound books.