Python Path Configuration File Creation - Windows

Status: test
Severity: medium
Log source: product windows, category file_event
Author: Andreas Braathen (mnemonic.io), Nasreddine Bencherchali (Nextron Systems)
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).

MITRE ATT&CK coverage

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

Event coverage

Provider	Event	Title
Sysmon	Event ID 11	FileCreate

Rule body yaml

title: Python Path Configuration File Creation - Windows
id: e3652ba3-0ad8-4010-a957-b7ba369e7bac
related:
    - id: fb96c26c-9f85-4ae7-af0d-ed1ed1f1f5ce # Linux
      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), Nasreddine Bencherchali (Nextron Systems)
date: 2024-04-25
tags:
    - attack.execution
    - attack.t1059.006
    - detection.threat-hunting
logsource:
    product: windows
    category: file_event
detection:
    selection:
        TargetFilename|re: '(?i)\\(venv|python(.+)?)\\lib\\site-packages\\' # Covers both Virtual envs and default paths
        TargetFilename|endswith: '.pth'
    filter_main_python:
        Image|endswith: '\python.exe'
        TargetFilename|endswith:
            - '\pywin32.pth' # VS Studio Python extension
            - '\distutils-precedence.pth'
    condition: selection and not 1 of filter_main_*
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 and not 1 of filter_main_*

Stage 1: `selection`

selection:
    TargetFilename|re: '(?i)\\(venv|python(.+)?)\\lib\\site-packages\\'
    TargetFilename|endswith: '.pth'

Stage 2: `not filter_main_python`

filter_main_python:
    Image|endswith: '\python.exe'
    TargetFilename|endswith:
        - '\pywin32.pth'
        - '\distutils-precedence.pth'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`TargetFilename`	ends_with	`\distutils-precedence.pth`
`TargetFilename`	ends_with	`\pywin32.pth`
`Image`	ends_with	`\python.exe`

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`TargetFilename`	ends_with	`.pth` corpus 3 (sigma 3)
`TargetFilename`	regex_match	`(?i)\(venv\|python(.+)?)\lib\site-packages\`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Python Path Configuration File Creation - Windows

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_python`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Python Path Configuration File Creation - Windows

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter_main_python

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_python`