The metrio package on PyPI, specifically versions 999.0.0, 1000.0.0, and 1001.0.0, contains malicious code that exfiltrates the local machine's hostname during installation and import. This exfiltration occurs by encoding the hostname and sending DNS and HTTP requests to an attacker-controlled domain. The package is designed as a dependency confusion proof-of-concept, aiming to be resolved instead of an internal package with the same name, thereby leaking information about the resolving host.