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Detection rules › Sigma

Powershell Store File In Alternate Data Stream

Status
test
Severity
medium
Log source
category ps_script, product windows
Author
frack113
Source
github.com/SigmaHQ/sigma

Storing files in Alternate Data Stream (ADS) similar to Astaroth malware.

MITRE ATT&CK coverage

TacticTechniques
Stealth

Telemetry coverage

ProviderRecord / event type
PowerShellEvent ID 4104: Creating Scriptblock text (MessageNumber of MessageTotal).

Rule body

title: Powershell Store File In Alternate Data Stream
id: a699b30e-d010-46c8-bbd1-ee2e26765fe9
status: test
description: Storing files in Alternate Data Stream (ADS) similar to Astaroth malware.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1564.004/T1564.004.md
author: frack113
date: 2021-09-02
modified: 2022-12-25
tags:
    - attack.stealth
    - attack.t1564.004
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection_compspec:
        ScriptBlockText|contains|all:
            - 'Start-Process'
            - '-FilePath "$env:comspec" '
            - '-ArgumentList '
            - '>'
    condition: selection_compspec
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

selection_compspec

Stage 1: selection_compspec

selection_compspec:
    ScriptBlockText|contains|all:
        - 'Start-Process'
        - '-FilePath "$env:comspec" '
        - '-ArgumentList '
        - '>'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
ScriptBlockTextmatch
  • -ArgumentList
  • -FilePath "$env:comspec"
  • >
  • Start-Process corpus 2 (sigma 2)
field:"ScriptBlockText" kind:match