When installing dependencies, Python package managers like pip will automatically execute build scripts distributed along with the
source code. The most common build script is setup.py, which runs arbitrary Python code during installation. Build scripts are a common
way to execute malicious code at install time whenever a package is compromised. The modern approach is to use pyproject.toml
instead, which does not execute arbitrary code during installation.
When package managers execute installation scripts, they run arbitrary code distributed with third-party packages. A compromised package can use this mechanism to execute malicious code on the build system, potentially stealing credentials, injecting backdoors, or otherwise compromising the supply chain.
If a dependency is compromised and its scripts are executed, an attacker can run arbitrary code with the permissions of the process performing the installation. This can lead to credential theft from the build environment, introduction of backdoors into the application, or lateral movement within CI/CD infrastructure.
pip install -r requirements.txt
pip install --only-binary :all: -r requirements.txt
poetry install
POETRY_INSTALLER_ONLY_BINARY=:all: poetry install
uv pip install -r requirements.txt # Noncompliant
uv sync # Noncompliant
uv run script.py # Noncompliant
uv tool run pkg # Noncompliant
uv pip install --no-build -r requirements.txt
uv sync --no-build
uv run --no-build script.py
uv tool run --no-build pkg