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Unusual File Creation - Alternate Data Stream

Identifies suspicious creation of Alternate Data Streams on highly targeted files. This is uncommon for legitimate files and sometimes done by adversaries to hide malware.

Rule type: eql

Rule indices:

  • winlogbeat-*
  • logs-endpoint.events.*
  • logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[Date Math format], see also Additional look-back time)

Maximum alerts per execution: 100

References: None

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Defense Evasion

Version: 100

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

Rule query

file where event.type == "creation" and

  file.path : "C:\\*:*" and
  not file.path : "C:\\*:zone.identifier*" and

  not process.executable :
          ("?:\\windows\\System32\\svchost.exe",
           "?:\\Windows\\System32\\inetsrv\\w3wp.exe",
           "?:\\Windows\\explorer.exe",
           "?:\\Windows\\System32\\sihost.exe",
           "?:\\Windows\\System32\\PickerHost.exe",
           "?:\\Windows\\System32\\SearchProtocolHost.exe",
           "?:\\Program Files (x86)\\Dropbox\\Client\\Dropbox.exe",
           "?:\\Program Files\\Rivet Networks\\SmartByte\\SmartByteNetworkService.exe",
           "?:\\Program Files (x86)\\Microsoft\\Edge\\Application\\msedge.exe",
           "?:\\Program Files\\ExpressConnect\\ExpressConnectNetworkService.exe",
           "?:\\Program Files (x86)\\Google\\Chrome\\Application\\chrome.exe",
           "?:\\Program Files\\Google\\Chrome\\Application\\chrome.exe",
           "?:\\Program Files\\Mozilla Firefox\\firefox.exe") and

  file.extension :
    (
      "pdf",
      "dll",
      "png",
      "exe",
      "dat",
      "com",
      "bat",
      "cmd",
      "sys",
      "vbs",
      "ps1",
      "hta",
      "txt",
      "vbe",
      "js",
      "wsh",
      "docx",
      "doc",
      "xlsx",
      "xls",
      "pptx",
      "ppt",
      "rtf",
      "gif",
      "jpg",
      "png",
      "bmp",
      "img",
      "iso"
    )

Framework: MITRE ATT&CKTM