Chinese APT Uses EggStreme Fileless Framework in Espionage
🛡️ Bitdefender attributed a campaign against a Philippines-based military contractor to a China-linked APT that deployed a previously undocumented fileless framework named EggStreme. The multi-stage operation begins with EggStremeFuel (mscorsvc.dll), which profiles systems, opens a C2 channel, stages loaders, and triggers in-memory execution of the core backdoor via DLL sideloading. EggStremeAgent functions as a central backdoor, injecting a session-specific keylogger (EggStremeKeylogger), communicating over gRPC, and exposing a 58-command toolkit for discovery, lateral movement, privilege escalation and data theft. An auxiliary implant, EggStremeWizard (xwizards.dll), provides reverse-shell access and resilient C2 options; Bitdefender warned that fileless execution and heavy DLL sideloading make detection and forensics difficult.
