Adam Griffin is still in disbelief over how quickly he was robbed of nearly $500,000 in cryptocurrencies. A scammer called using a real Google phone number to warn his Gmail account was being hacked, sent email security alerts directly from google.com, and ultimately seized control over the account by convincing him to click “yes” to a Google prompt on his mobile device.

Griffin is a battalion chief firefighter in the Seattle area, and on May 6 he received a call from someone claiming they were from Google support saying his account was being accessed from Germany. A Google search on the phone number calling him — (650) 203-0000 — revealed it was an official number for Google Assistant, an AI-based service that can engage in two-way conversations.

At the same time, he received an email that came from a google.com email address, warning his Google account was compromised. The message included a “Google Support Case ID number” and information about the Google representative supposedly talking to him on the phone, stating the rep’s name as “Ashton” — the same name given by the caller.

Griffin didn’t learn this until much later, but the email he received had a real google.com address because it was sent via Google Forms, a service available to all Google Docs users that makes it easy to send surveys, quizzes and other communications.