Windows PowerShell: Suspicious Unblock-File to Remove Zone.Identifier
Flags PowerShell use of Unblock-File (-Path) that can remove Zone.Identifier downloaded-file metadata.
- Product
- windows
- Category
- ps_script
- Author
- frack113 (SigmaHQ), DRL 1.1
- Published
- 2022-02-01
- Updated
- 2026-07-31
ATT&CK techniques
Defense EvasionRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule flags PowerShell script block content that calls Unblock-File with a -Path argument, indicating removal of the Zone.Identifier alternate data stream. Attackers may use this to reduce evidence that a file was downloaded from the internet, impairing user and security visibility. Detection relies on Script Block Logging capturing the PowerShell command text containing the expected arguments.
Reporting behind it
- github.comhttps://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1553.005/T1553.005.md#atomic-test-3---remove-the-zoneidentifier-alternate-data-stream
- learn.microsoft.comhttps://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/unblock-file?view=powershell-7.2
- github.comhttps://github.com/SigmaHQ/sigma/blob/master/rules/windows/powershell/powershell_script/posh_ps_susp_unblock_file.yml
Changelog
v2- v2Candidate ingested via manual entry.2026-07-31
- v1No 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.
title: "Windows PowerShell: Suspicious Unblock-File to Remove Zone.Identifier"
id: 80aac208-ee81-41f4-85a4-493ed16d2381
status: test
description: This rule flags PowerShell script block content that calls Unblock-File with a -Path argument, indicating removal of the Zone.Identifier alternate data stream. Attackers may use this to reduce evidence that a file was downloaded from the internet, impairing user and security visibility. Detection relies on Script Block Logging capturing the PowerShell command text containing the expected arguments.
references:
- https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1553.005/T1553.005.md#atomic-test-3---remove-the-zoneidentifier-alternate-data-stream
- https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/unblock-file?view=powershell-7.2
- https://github.com/SigmaHQ/sigma/blob/master/rules/windows/powershell/powershell_script/posh_ps_susp_unblock_file.yml
author: frack113, Huntrule Team
date: 2022-02-01
tags:
- attack.defense-impairment
- attack.t1553.005
logsource:
product: windows
category: ps_script
definition: "Requirements: Script Block Logging must be enabled"
detection:
selection:
ScriptBlockText|contains|all:
- "Unblock-File "
- "-Path "
condition: selection
falsepositives:
- Legitimate PowerShell scripts
level: medium
license: DRL-1.1
related:
- id: 5947497f-1aa4-41dd-9693-c9848d58727d
type: derived