Windows Process Creation: CLI CommandLine References NTFS ::$index_allocation Stream
Flags Windows CLI commands referencing the NTFS ::$index_allocation stream for potential hidden directory activity.
- Product
- windows
- Category
- process_creation
- Author
- Nasreddine Bencherchali (Nextron Systems), Scoubi (@ScoubiMtl) (SigmaHQ), DRL 1.1
- Published
- 2023-10-09
- Updated
- 2026-07-30
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 Windows process creation events where the CommandLine contains a reference to the NTFS "::$index_allocation" stream. Attackers may use this stream to hide files or folders from common access and tooling, increasing stealth. Telemetry relies on process creation logging with a captured CommandLine and matches only on the presence of the "::$index_allocation" substring.
Reporting behind it
- twitter.comhttps://twitter.com/pfiatde/status/1681977680688738305
- soroush.mehttps://soroush.me/blog/2010/12/a-dotty-salty-directory-a-secret-place-in-ntfs-for-secret-files/
- sec-consult.comhttps://sec-consult.com/blog/detail/pentesters-windows-ntfs-tricks-collection/
- github.comhttps://github.com/redcanaryco/atomic-red-team/blob/5c3b23002d2bbede3c07e7307165fc2a235a427d/atomics/T1564.004/T1564.004.md#atomic-test-5---create-hidden-directory-via-index_allocation
- learn.microsoft.comhttps://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/c54dec26-1551-4d3a-a0ea-4fa40f848eb3
- github.comhttps://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_susp_hidden_dir_index_allocation.yml
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
title: "Windows Process Creation: CLI CommandLine References NTFS ::$index_allocation Stream"
id: 0c5e53a1-eb3e-423f-858f-b48fcb000a46
related:
- id: a8f866e1-bdd4-425e-a27a-37619238d9c7
type: similar
- id: 0900463c-b33b-49a8-be1d-552a3b553dae
type: derived
status: test
description: This rule flags Windows process creation events where the CommandLine contains a reference to the NTFS "::$index_allocation" stream. Attackers may use this stream to hide files or folders from common access and tooling, increasing stealth. Telemetry relies on process creation logging with a captured CommandLine and matches only on the presence of the "::$index_allocation" substring.
references:
- https://twitter.com/pfiatde/status/1681977680688738305
- https://soroush.me/blog/2010/12/a-dotty-salty-directory-a-secret-place-in-ntfs-for-secret-files/
- https://sec-consult.com/blog/detail/pentesters-windows-ntfs-tricks-collection/
- https://github.com/redcanaryco/atomic-red-team/blob/5c3b23002d2bbede3c07e7307165fc2a235a427d/atomics/T1564.004/T1564.004.md#atomic-test-5---create-hidden-directory-via-index_allocation
- https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/c54dec26-1551-4d3a-a0ea-4fa40f848eb3
- https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_susp_hidden_dir_index_allocation.yml
author: Nasreddine Bencherchali (Nextron Systems), Scoubi (@ScoubiMtl), Huntrule Team
date: 2023-10-09
tags:
- attack.stealth
- attack.t1564.004
logsource:
product: windows
category: process_creation
detection:
selection:
CommandLine|contains: ::$index_allocation
condition: selection
falsepositives:
- Unlikely
level: medium
license: DRL-1.1