Suspicious PowerShell Parameter Substring

Detects suspicious PowerShell invocation with a parameter substring

Rule Content

- title: Suspicious PowerShell Parameter Substring
  id: 36210e0d-5b19-485d-a087-c096088885f0
  status: experimental
  description: Detects suspicious PowerShell invocation with a parameter substring
  references:
  - http://www.danielbohannon.com/blog-1/2017/3/12/powershell-execution-argument-obfuscation-how-it-can-make-detection-easier
  tags:
  - attack.execution
  - attack.t1086
  author: Florian Roth (rule), Daniel Bohannon (idea), Roberto Rodriguez (Fix)
  logsource:
    category: process_creation
    product: windows
    service: null
  detection:
    selection:
      Image:
      - '*\Powershell.exe'
      CommandLine:
      - ' -windowstyle h '
      - ' -windowstyl h'
      - ' -windowsty h'
      - ' -windowst h'
      - ' -windows h'
      - ' -windo h'
      - ' -wind h'
      - ' -win h'
      - ' -wi h'
      - ' -win h '
      - ' -win hi '
      - ' -win hid '
      - ' -win hidd '
      - ' -win hidde '
      - ' -NoPr '
      - ' -NoPro '
      - ' -NoProf '
      - ' -NoProfi '
      - ' -NoProfil '
      - ' -nonin '
      - ' -nonint '
      - ' -noninte '
      - ' -noninter '
      - ' -nonintera '
      - ' -noninterac '
      - ' -noninteract '
      - ' -noninteracti '
      - ' -noninteractiv '
      - ' -ec '
      - ' -encodedComman '
      - ' -encodedComma '
      - ' -encodedComm '
      - ' -encodedCom '
      - ' -encodedCo '
      - ' -encodedC '
      - ' -encoded '
      - ' -encode '
      - ' -encod '
      - ' -enco '
      - ' -en '
    condition: selection
  falsepositives:
  - Penetration tests
  level: high

Querying Elasticsearch

Import Libraries



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from elasticsearch import Elasticsearch
from elasticsearch_dsl import Search
import pandas as pd

Initialize Elasticsearch client



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es = Elasticsearch(['http://helk-elasticsearch:9200'])
searchContext = Search(using=es, index='logs-*', doc_type='doc')

Run Elasticsearch Query



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s = searchContext.query('query_string', query='(process_path.keyword:(*\\Powershell.exe) AND process_command_line:("\ \-windowstyle\ h\ " OR "\ \-windowstyl\ h" OR "\ \-windowsty\ h" OR "\ \-windowst\ h" OR "\ \-windows\ h" OR "\ \-windo\ h" OR "\ \-wind\ h" OR "\ \-win\ h" OR "\ \-wi\ h" OR "\ \-win\ h\ " OR "\ \-win\ hi\ " OR "\ \-win\ hid\ " OR "\ \-win\ hidd\ " OR "\ \-win\ hidde\ " OR "\ \-NoPr\ " OR "\ \-NoPro\ " OR "\ \-NoProf\ " OR "\ \-NoProfi\ " OR "\ \-NoProfil\ " OR "\ \-nonin\ " OR "\ \-nonint\ " OR "\ \-noninte\ " OR "\ \-noninter\ " OR "\ \-nonintera\ " OR "\ \-noninterac\ " OR "\ \-noninteract\ " OR "\ \-noninteracti\ " OR "\ \-noninteractiv\ " OR "\ \-ec\ " OR "\ \-encodedComman\ " OR "\ \-encodedComma\ " OR "\ \-encodedComm\ " OR "\ \-encodedCom\ " OR "\ \-encodedCo\ " OR "\ \-encodedC\ " OR "\ \-encoded\ " OR "\ \-encode\ " OR "\ \-encod\ " OR "\ \-enco\ " OR "\ \-en\ "))')
response = s.execute()
if response.success():
    df = pd.DataFrame((d.to_dict() for d in s.scan()))

Show Results



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df.head()