Suspicious Code Page Switch

Detects a code page switch in command line or batch scripts to a rare language

Rule Content

- title: Suspicious Code Page Switch
  id: c7942406-33dd-4377-a564-0f62db0593a3
  status: experimental
  description: Detects a code page switch in command line or batch scripts to a rare
    language
  author: Florian Roth
  date: 2019/10/14
  references:
  - https://docs.microsoft.com/en-us/windows/win32/intl/code-page-identifiers
  - https://twitter.com/cglyer/status/1183756892952248325
  logsource:
    category: process_creation
    product: windows
    service: null
  detection:
    selection:
      CommandLine:
      - chcp* 936
      - chcp* 1258
    condition: selection
  fields:
  - ParentCommandLine
  falsepositives:
  - Administrative activity (adjust code pages according to your organisation's region)
  level: medium

Querying Elasticsearch

Import Libraries



In [ ]:

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

Initialize Elasticsearch client



In [ ]:

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

Run Elasticsearch Query



In [ ]:

    
s = searchContext.query('query_string', query='process_command_line.keyword:(chcp*\ 936 OR chcp*\ 1258)')
response = s.execute()
if response.success():
    df = pd.DataFrame((d.to_dict() for d in s.scan()))

Show Results



In [ ]:

    
df.head()