t1546-018-python-startup-hooks

name	T1546.018_python-startup-hooks
description	Adversaries may achieve persistence by leveraging Python’s startup mechanisms, including path configuration (`.pth`) files and the `sitecustomize.py` or `usercustomize.py` modules.
category	configuration
version	18.1
author	cyberstrike-official
tags	["mitre-attack","enterprise","t1546.018","persistence","privilege-escalation","linux","macos","windows","sub-technique"]
technique_id	T1546.018
tactic	persistence
all_tactics	["persistence","privilege-escalation"]
platforms	["Linux","macOS","Windows"]
mitre_url	https://attack.mitre.org/techniques/T1546/018
tech_stack	["linux","macos","windows"]
cwe_ids	["CWE-276"]
chains_with	["T1546","T1546.001","T1546.002","T1546.003","T1546.004","T1546.005","T1546.006","T1546.007","T1546.008","T1546.009","T1546.010","T1546.011","T1546.012","T1546.013","T1546.014","T1546.015","T1546.016","T1546.017"]
prerequisites	["T1546"]
severity_boost	{"T1546":"Chain with T1546 for deeper attack path","T1546.001":"Chain with T1546.001 for deeper attack path","T1546.002":"Chain with T1546.002 for deeper attack path"}

T1546.018 Python Startup Hooks

Sub-technique of: T1546

High-Level Description

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.

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. 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.

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

Kill Chain Phase

• Persistence (TA0003)
• Privilege Escalation (TA0004)

Platforms: Linux, macOS, Windows

What to Check

• Identify if Python Startup Hooks technique is applicable to target environment
• Check Linux systems for indicators of Python Startup Hooks
• Check macOS systems for indicators of Python Startup Hooks
• Check Windows systems for indicators of Python Startup Hooks
• Assess detection coverage (1 detection strategies)

How to Test

Atomic Red Team Tests

The following tests are from Atomic Red Team and provide actionable ways to test this technique:

Atomic Test 1: Python Startup Hook - atomic_hook.pth (Windows)

Executes code by placing a .pth file in the site-packages directory. Supports python.exe and python3.exe via input arguments.

Supported Platforms: windows

$TempDir = Join-Path $env:TEMP "atomic_pth_win"
New-Item -ItemType Directory -Path $TempDir -Force
& "#{python_exe}" -m venv "$TempDir\env"
$SitePackages = & "$TempDir\env\Scripts\python.exe" -c "import site; print(site.getsitepackages()[1])"
"import os, subprocess; os.environ.get('CALC_SPAWNED') or (os.environ.update({'CALC_SPAWNED':'1'}) or subprocess.Popen(['calc.exe']))" | Out-File -Encoding ASCII "$SitePackages\atomic_hook.pth"
Get-ChildItem -Path "$SitePackages" | Where-Object { $_.Name -like "*.pth" }
& "$TempDir\env\Scripts\python.exe" -c "print('Triggering Hook via atomic_hook...')"