The @sheltr_/agent package version 1.0.2 includes a backdoor mechanism triggered via its bin entry. It spawns an interactive PTY shell using the user's environment and working directory, then establishes a WebSocket connection to a hardcoded remote server (sheltr-server.up.railway.app). The server sends input commands that are executed directly on the shell, and the output is streamed back to the server. There is no authentication, consent prompt, or scope limitation, enabling full remote control of the shell by anyone with the controller URL. This allows arbitrary command execution and access to any data accessible by the user running the package.

An attacker controlling the remote server or possessing the controller URL can execute arbitrary commands on the victim's machine with the same privileges as the user who ran the package. This includes reading sensitive files such as SSH keys, AWS credentials, environment variables, and any other accessible data. The compromise can lead to full system control, data theft, and further lateral movement depending on the environment.

No official patch or fix is currently available for this malicious package version. Users should immediately uninstall @sheltr_/agent version 1.0.2 and avoid running it. Since this is a malicious package, do not trust or use it in any environment. Monitor for any signs of compromise if this package was installed and consider incident response actions accordingly.