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APT41-Linked Silver Dragon Targets Governments with Cobalt Strike and Google Drive C2

Check Point researchers disclose Silver Dragon, a China-linked APT group tied to APT41, targeting government entities across Europe and Southeast Asia using Cobalt Strike beacons, DNS tunneling, and a novel .NET backdoor that communicates through Google Drive.

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Check Point Research has disclosed Silver Dragon, an APT group tied to the China-linked APT41 threat actor, targeting government entities in Europe and Southeast Asia since mid-2024. The group uses a sophisticated toolchain that includes Cobalt Strike beacons, DNS tunneling, and a novel .NET backdoor called GearDoor that communicates through Google Drive.

Attack Infrastructure

Silver Dragon's primary command-and-control mechanism abuses Google Drive as a communication channel. The GearDoor backdoor uploads encrypted status reports and command responses to attacker-controlled Google Drive folders, and downloads new commands from the same locations. This technique makes C2 traffic difficult to distinguish from legitimate Google Drive usage — a significant challenge for network security monitoring tools that typically allow Google Drive traffic without inspection.

Post-Exploitation Tools

Once inside a target network, Silver Dragon deploys custom post-exploitation tools including SilverScreen (a screen monitoring tool that captures screenshots at configurable intervals and exfiltrates them through the Google Drive C2 channel) and SSHcmd (a remote command execution tool that creates an SSH tunnel to attacker infrastructure for interactive access). The group also uses DNS tunneling as a backup C2 channel, encoding commands and responses in DNS queries to attacker-controlled domains.

Targets and Attribution

Check Point's investigation identified government ministries, diplomatic missions, and defense-related organizations across Europe and Southeast Asia as primary targets. The group's tooling, infrastructure patterns, and target selection align with APT41's known operational profile — a Chinese state-sponsored group that conducts both espionage operations for intelligence purposes and financially motivated cybercrime. The dual-purpose nature of APT41's operations makes attribution complex, as the same tooling is used for both state-directed and personal financial operations.

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