The npm package 'claude-internal-utils' version 9.0.5 is a malicious package impersonating an internal Anthropic namespace. It contains no legitimate library code but executes a postinstall script that collects system and environment information, including the installer's public IP, hostname, current working directory, and environment variables. This data is exfiltrated to a hardcoded attacker-controlled domain. The malicious code runs automatically during 'npm install' before any consumer code executes.