A hotel-booking phishing scam is slipping straight past email security filters
On 25 June, Microsoft Threat Intelligence went public with a phishing campaign that's been targeting hotels and hospitality businesses across Europe and Asia since April. The emails arrive from "Booking Manager (via Calendly)" and reference believable front-desk problems — guest complaints, room enquiries, even health inspections — to get staff to open an attached "photo" ZIP.
The clever, nasty part is how it reaches the inbox at all. By routing the message through Calendly's own verified servers, the attackers borrow Calendly's good reputation so the email sails through standard security filters — a trick Microsoft has named "authentication laundering." Open the ZIP and a hidden chain installs a Node.js implant that quietly adds itself to Microsoft Defender's exclusion list and phones home for remote control.