Python Path Configuration File Creation - Linux

Status: test
Severity: medium
Log source: category file_event, product linux
Author: Andreas Braathen (mnemonic.io)
Source: github.com/SigmaHQ/sigma

Detects creation of a Python path configuration file (.pth) in Python library folders, which can be maliciously abused for code execution and persistence. Modules referenced by these files are run at every Python startup (v3.5+), regardless of whether the module is imported by the calling script. Default paths are '\lib\site-packages*.pth' (Windows) and '/lib/pythonX.Y/site-packages/*.pth' (Unix and macOS).

Known false positives

Although .pth files are discouraged due to potential security implications, these are legitimate files by specification.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.006` Command and Scripting Interpreter: Python

Telemetry coverage

Platform	Record / event type
Linux	Event ID 11: File created

Rule body

title: Python Path Configuration File Creation - Linux
id: fb96c26c-9f85-4ae7-af0d-ed1ed1f1f5ce
related:
    - id: e3652ba3-0ad8-4010-a957-b7ba369e7bac # Windows
      type: similar
    - id: 4f394635-13ef-4599-b677-3353e0f84f55 # MacOS
      type: similar
status: test
description: |
    Detects creation of a Python path configuration file (.pth) in Python library folders, which can be maliciously abused for code execution and persistence.
    Modules referenced by these files are run at every Python startup (v3.5+), regardless of whether the module is imported by the calling script.
    Default paths are '\lib\site-packages\*.pth' (Windows) and '/lib/pythonX.Y/site-packages/*.pth' (Unix and macOS).
references:
    - https://www.volexity.com/blog/2024/04/12/zero-day-exploitation-of-unauthenticated-remote-code-execution-vulnerability-in-globalprotect-cve-2024-3400/
    - https://www.virustotal.com/gui/file/3de2a4392b8715bad070b2ae12243f166ead37830f7c6d24e778985927f9caac
    - https://docs.python.org/3/library/site.html
author: Andreas Braathen (mnemonic.io)
date: 2024-04-25
tags:
    - attack.execution
    - attack.t1059.006
    - detection.threat-hunting
logsource:
    product: linux
    category: file_event
detection:
    selection:
        TargetFilename|re: '(?i)/lib/python3\.([5-9]|[0-9]{2})/site-packages/' # Unix and macOS
        TargetFilename|endswith: '.pth'
    condition: selection
falsepositives:
    - Although .pth files are discouraged due to potential security implications, these are legitimate files by specification.
level: medium

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    TargetFilename|re: '(?i)/lib/python3\.([5-9]|[0-9]{2})/site-packages/'
    TargetFilename|endswith: '.pth'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`TargetFilename`	ends_with	`.pth`	`field:"TargetFilename" kind:ends_with value:".pth"`
`TargetFilename`	regex_match	`(?i)/lib/python3.([5-9]\|[0-9]{2})/site-packages/`	`field:"TargetFilename" kind:regex_match value:"(?i)/lib/python3.([5-9]\|[0-9]{2})/site-packages/"`