Malware
ZxxZ
aka MuuyDownloader
Cisco Talos attributes this backdoor with moderate confidence to the Bitter APT.
ZxxZ, also known as MuuyDownloader, is a Windows malware family operated by HAZY TIGER.
Background
Cisco Talos links this backdoor to the Bitter APT group, assessing the attribution with a moderate level of confidence.
Source: Malpedia (Fraunhofer FKIE).