The requests-toolbelt-plus package on PyPI is a malicious package impersonating the legitimate requests-toolbelt library. During installation, it executes code that checks if the environment is Windows Subsystem for Linux (WSL). If so, it connects to a hardcoded attacker IP, sends system information, and establishes a persistent reverse shell via modifications to the user's .bashrc file. This allows full remote command execution and persistent access on affected developer machines running WSL.