PowerShell NTFS Alternate Data Stream Writes via set-content/add-content

Alerts on PowerShell Set/Add-Content operations that specify -Stream, indicating potential NTFS Alternate Data Stream writes.

FreeReviewedSigma · High · v2

Product: windows
Category: ps_script
Author: Sami Ruohonen (SigmaHQ), DRL 1.1
Published: 2018-07-24
Updated: 2026-07-31

Analysis Detection

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1059.001PowerShell
Persistence
Priv Esc
Defense Evasion
- T1564.004NTFS File Attributes
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule identifies PowerShell script blocks that write to NTFS alternate data streams by combining set-content or add-content with the -stream parameter. Attackers can use alternate data streams to hide or stage content within NTFS files, making this behavior relevant for stealthy data concealment. It relies on PowerShell Script Block Logging telemetry to capture ScriptBlockText content matching these cmdlets and the -stream argument.

Reporting behind it

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PowerShell NTFS Alternate Data Stream Writes via set-content/add-content

Pivot detection · T1059.001 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

powershell-writes-to-ntfs-alternate-data-streams-via-stream-with-set-add-content-8c521530

title: PowerShell NTFS Alternate Data Stream Writes via set-content/add-content
id: c3150474-e6e3-45c4-aa7b-7b38201931fa
status: test
description: This rule identifies PowerShell script blocks that write to NTFS alternate data streams by combining set-content or add-content with the -stream parameter. Attackers can use alternate data streams to hide or stage content within NTFS files, making this behavior relevant for stealthy data concealment. It relies on PowerShell Script Block Logging telemetry to capture ScriptBlockText content matching these cmdlets and the -stream argument.
references:
  - https://web.archive.org/web/20220614030603/http://www.powertheshell.com/ntfsstreams/
  - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1564.004/T1564.004.md
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/powershell/powershell_script/posh_ps_ntfs_ads_access.yml
author: Sami Ruohonen, Huntrule Team
date: 2018-07-24
modified: 2022-12-25
tags:
  - attack.stealth
  - attack.t1564.004
  - attack.execution
  - attack.t1059.001
logsource:
  product: windows
  category: ps_script
  definition: "Requirements: Script Block Logging must be enabled"
detection:
  selection_content:
    ScriptBlockText|contains:
      - set-content
      - add-content
  selection_stream:
    ScriptBlockText|contains: -stream
  condition: all of selection*
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: 8c521530-5169-495d-a199-0a3a881ad24e
    type: derived

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