Hackers recently exploited a weakness in Google’s email system to carry out a sophisticated phishing attack. By leveraging Google’s infrastructure, they sent fake emails that appeared legitimate, passing all verification checks, including DomainKeys Identified Mail (DKIM). The fraudulent emails directed victims to a fake “support portal” that requested Google account credentials, making the attack appear to come from Google itself. In this particular case, Ethereum Name Service (ENS) developer Nick Johnson received a phishing email that looked like an official alert from Google regarding a subpoena.
The email included a link to a fraudulent Google support page, which was hosted on Google’s free website-building platform, sites.google.com. This clever trick made the email seem even more authentic, as it came from a Google-owned domain. The message was designed to deceive even technically savvy users, as it passed DKIM checks and appeared to be a legitimate notification. However, Johnson’s attention to detail helped him spot the anomaly—he noticed that the support portal was hosted on the wrong Google subdomain, raising his suspicion about the email’s legitimacy.
The attack used a DKIM replay phishing method to bypass security checks, making the message seem genuine despite being sent from a fraudulent source.
In this approach, the attacker created a Google OAuth app, which allowed them to generate a Google security alert. Since Google’s DKIM checks validate only the email message and headers, not the envelope, the attack email passed all security tests. As a result, it appeared legitimate to the recipient and was delivered directly to their inbox.
This phishing tactic is not unique to Google. A similar attack was attempted on PayPal users, where attackers used a DKIM replay phishing method to send fraudulent emails through PayPal’s mail servers. Both incidents demonstrate the vulnerabilities in DKIM checks, which can be exploited to make phishing emails look legitimate. Security experts continue to warn about these types of attacks, stressing the importance of awareness and careful scrutiny of email sources.
