Empty User Agent

Detects suspicious empty user agent strings in proxy logs

Rule Content

- title: Empty User Agent
  id: 21e44d78-95e7-421b-a464-ffd8395659c4
  status: experimental
  description: Detects suspicious empty user agent strings in proxy logs
  references:
  - https://twitter.com/Carlos_Perez/status/883455096645931008
  author: Florian Roth
  logsource:
    category: proxy
    product: null
    service: null
  detection:
    selection:
      c-useragent: ''
    condition: selection
  fields:
  - ClientIP
  - c-uri
  - c-useragent
  falsepositives:
  - Unknown
  level: medium

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='c-useragent:""')
response = s.execute()
if response.success():
    df = pd.DataFrame((d.to_dict() for d in s.scan()))

Show Results



In [ ]:

    
df.head()