FatDuke
Intelligence Profile
According to ESET Research, FatDuke is the current flagship backdoor of APT29 and is only deployed on the most interesting machines. It is generally dropped by the MiniDuke backdoor, but ESET also have seen the operators dropping FatDuke using lateral movement tools such as PsExec.The operators regularly repack this malware in order to evade detections. The most recent sample of FatDuke that ESET have seen was compiled on May 24, 2019. They have seen them trying to regain control of a machine multiple times in a few days, each time with a different sample. Their packer, described in a later section, adds a lot of code, leading to large binaries. While the effective code should not be larger than 1MB, ESET have seen one sample weighing in at 13MB, hence our name for this backdoor component: FatDuke.
Threat Analysis
FatDuke is a malware family tracked by threat intelligence researchers and catalogued in the Malpedia dataset. It represents a distinct malicious software lineage with identifiable code characteristics, behaviors, and victimology.
The group's espionage-oriented operations suggest a state-sponsored or state-aligned mandate, typically focused on stealing intellectual property, government secrets, or military intelligence. Targets are usually selected for strategic value rather than financial gain.
Classified as an advanced threat actor, FatDuke likely develops or acquires zero-day exploits, employs custom malware toolchains, and demonstrates long-term persistence capabilities — hallmarks of a well-resourced operation consistent with nation-state backing.