arc-diag-util@1.0.1

Summary

On npm install, the package's postinstall hook runs id to capture the installer's uid/gid/group identity and opens a raw TCP socket to host.docker.internal:9999, writing the command output to that listener. The package's declared main (index.js) is a two-line stub exporting {} — there is no library functionality, the postinstall beacon is the package's sole purpose. host.docker.internal resolves to the Docker host from inside a container, so the pattern is specifically designed to escape sandboxed CI/build containers and report installer identity to a listener on the build host. The hollow library body combined with a generic 'diagnostic utility' name is consistent with a dependency-confusion attempt against an internal package name.

Source: amazon-inspector (95f08d97107d726a6ae90afbf8e354b84a7e13d4a236bc8766180a362cc8344c)