The @ccfly/setup-linux-x64 npm package ships a single 6.9 MB Linux/x64 Go executable without source code. This binary includes functionality for spawning pseudo-terminals and WebSocket clients, connecting to hardcoded attacker-controlled servers (ws://ccflycc.hn, wss://, https://cc.hn). It implements a remote-controlled shell/executor architecture that allows persistent WebSocket communication and privileged package installations via apt-get, pacman, or zypper after a remote 'approve' step. The package.json metadata does not trigger execution on npm install; the backdoor activates only when a companion @ccfly wrapper CLI resolves this optional dependency and invokes the binary. The use of unencrypted ws:// connections and lack of source code prevent independent audit and increase risk.

An attacker controlling the command-and-control servers can gain full command execution and privileged package installation capabilities on any host running the binary. This enables remote compromise, persistent backdoor access, and potential system takeover on affected Linux/x64 systems where the binary is invoked. The threat is significant due to the ability to execute arbitrary commands with elevated privileges.

No official patch or remediation is currently documented. Users should avoid installing or invoking the @ccfly/setup-linux-x64 package and its companion @ccfly wrapper CLI. Since the backdoor activates only when the binary is invoked by the wrapper CLI, preventing use of this CLI or removing the package from environments is recommended. Monitor for and remove any instances of this package and related binaries. Patch status is not yet confirmed — check the vendor advisory or trusted sources for updates.