Unusual File Creation - Alternate Data Stream

Unusual File Creation - Alternate Data Streamedit

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 (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: 2

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guideedit

## Config

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.

Rule queryedit

file where event.type == "creation" and
  file.path : "C:\\*:*" and
  not file.path : "C:\\*:zone.identifier*" 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