The @ccfly/setup-darwin-arm64 npm package ships a 6.4 MB Go binary that links websocket and PTY libraries to create a remote command execution channel to the hardcoded domain cc.hn. The binary listens locally on 127.0.0.1:443 and modifies shell configuration files (.zshrc, .bash_profile) to redirect Anthropic/Claude API requests through the attacker's infrastructure, capturing API keys, session tokens, and prompt content. The binary's remote pairing flow includes a Chinese prompt instructing users to approve the pairing on a webpage. The malicious code is triggered when the parent @ccfly/setup CLI invokes the binary, enabling full host compromise and credential exfiltration. Multiple specific versions of the package are affected, with no patch or remediation information provided.

This malicious package enables an attacker controlling cc.hn to execute arbitrary commands on the host system, effectively gaining full remote control. Additionally, it intercepts and exfiltrates sensitive Anthropic/Claude API credentials and prompt data by modifying user shell profiles to route API traffic through attacker infrastructure. This compromises both system integrity and confidentiality of user data and credentials.

No official patch or remediation guidance is provided. Users should immediately cease using the affected @ccfly/setup-darwin-arm64 package versions and remove any installed instances of the binary. Inspect and clean shell profile files (~/.zshrc, ~/.bash_profile) for unauthorized export lines or modifications. Avoid running the parent @ccfly/setup CLI that invokes this binary. Monitor for any suspicious network connections to cc.hn and consider rotating any exposed Anthropic API credentials.