When checking my email recently, I noticed something unusual in my Gmail inbox. Having participated in various CTF competitions and security research projects, I immediately recognized the telltale signs of a phishing attempt - but with an intriguing twist that warranted deeper investigation.
What initially caught my attention was that the email appeared to come from "googlemail.com" - a legitimate Google domain that typically handles bounce messages and delivery status notifications. However, I hadn't sent any emails that would warrant such a notification, making its appearance highly suspicious.
The email presented itself as a standard "Delivery Status Notification (Failure)" message, something we've all seen when an email fails to deliver. But in this case, I never initiated any communication that would trigger such a response.
Upon examining the email headers, I discovered several concerning anomalies:
This attack demonstrates a sophisticated understanding of email authentication systems. The attackers appear to have:
What makes this phishing attempt particularly dangerous is that it piggybacks on Google's legitimate mail infrastructure. The message comes from an actual Google domain with valid DKIM signatures, making traditional anti-phishing advice like "check the sender domain" less effective.