Russian APT28 Deploys “NotDoor” Outlook Backdoor Against Companies in NATO Countries post, september 4, 2025september 5, 2025 The Russian state-sponsored hacking group tracked as APT28 has been attributed to a new Microsoft Outlook backdoor called NotDoor in attacks targeting multiple companies from different sectors in NATO member countries. NotDoor “is a VBA macro for Outlook designed to monitor incoming emails for a specific trigger word,” S2 Grupo’s LAB52 threat intelligence team said. “When such an email is detected, it enables an attacker to exfiltrate data, upload files, and execute commands on the victim’s computer.” Russian APT28 Deploys “NotDoor” Outlook Backdoor Against Companies in NATO Countries: Russian APT28 Deploys “NotDoor” Outlook Backdoor Against Companies in NATO Countries vulnerability 2025Russia