Sigma rule: Suspicious Unblock-File

Rule

Title

Suspicious Unblock-File

Status

test

Level

medium

Author

frack113

Date

2022-02-01

File

rules/windows/powershell/powershell_script/posh_ps_susp_unblock_file.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Remove the Zone.Identifier alternate data stream which identifies the file as downloaded from the internet.

Log source

product

windows

category

ps_script

definition

Requirements: Script Block Logging must be enabled

Detection

selection:
    ScriptBlockText|contains|all:
        - 'Unblock-File '
        - '-Path '
condition: selection

False positives (as the rule lists them)

• Legitimate PowerShell scripts

Tags

• attack.defense-impairment
• attack.t1553.005

MITRE ATT&CK ids this rule names

• T1553.005

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

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/powershell/powershell_script/posh_ps_susp_unblock_file.yml