Python Startup Hooks

Adversaries may achieve persistence by leveraging Python’s startup mechanisms, including path configuration (.pth) files and the sitecustomize.py or usercustomize.py modules. These files are automatically processed during the initialization of the Python interpreter, allowing for the execution of arbitrary code whenever Python is invoked.(Citation: Volexity GlobalProtect CVE 2024)

Path configuration files are designed to extend Python’s module search paths through the use of import statements. If a .pth file is placed in Python's site-packages or dist-packages directories, any lines beginning with import will be executed automatically on Python invocation.(Citation: DFIR Python Persistence 2025) Similarly, if sitecustomize.py or usercustomize.py is present in the Python path, these files will be imported during interpreter startup, and any code they contain will be executed.(Citation: Python Site Configuration Hook)

Adversaries may abuse these mechanisms to establish persistence on systems where Python is widely used (e.g., for automation or scripting in production environments).