KAZUAR is a sophisticated malware family attributed to the Russian state actor Secret Blizzard and described as a modular peer-to-peer botnet designed to provide persistent, covert access for espionage purposes. The threat group has historically targeted government and diplomatic organisations in Europe and Central Asia, including Ukrainian systems previously compromised by Aqua Blizzard, with the likely aim of supporting Russia’s foreign policy and military objectives.
Kazuar operates as three distinct module types—Kernel, Bridge, and Worker—each with defined roles, enabling flexible tasking, data staging, and multiple fallback channels for C2 communications while minimising observable footprint. The architecture uses a single elected Kernel leader to limit external traffic and employs IPC mechanisms such as named pipes, mailslots, and Windows Messaging, with REST-like Protobuf-based messages guiding inter-module communication and external routing via the Bridge to C2.
The ransomware-like delivery chain involves dropper variants that embed encrypted payloads or load a small loader, and the system gathers extensive telemetry including system information, window activity, and MAPI data for exfiltration. According to Microsoft Threat Intelligence, the activity is linked to Secret Blizzard and is detectable via specific Defender detections and threat analytics.