Unusual File Creation - Alternate Data Stream

edit

Unusual File Creation - Alternate Data Stream

edit

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 guide

edit
## 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 query

edit
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