Detection rules › Sigma

Suspicious Start-Process PassThru

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

Powershell use PassThru option to start in background

Known false positives

  • Legitimate PowerShell scripts

MITRE ATT&CK coverage

Telemetry coverage

Rule body

title: Suspicious Start-Process PassThru
id: 0718cd72-f316-4aa2-988f-838ea8533277
status: test
description: Powershell use PassThru option to start in background
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1036.003/T1036.003.md
    - https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.management/start-process?view=powershell-7.6
author: frack113
date: 2022-01-15
modified: 2026-05-18
tags:
    - attack.stealth
    - attack.t1036.003
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection_cmdlet:
        ScriptBlockText|contains:
            - 'Start-Process '
            - 'saps '
    selection_param:
        ScriptBlockText|contains|all:
            - '-PassThru '
            - '-FilePath '
    condition: all of selection_*
falsepositives:
    - Legitimate PowerShell scripts
level: medium

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_cmdlet

selection_cmdlet:
    ScriptBlockText|contains:
        - 'Start-Process '
        - 'saps '

Stage 2: selection_param

selection_param:
    ScriptBlockText|contains|all:
        - '-PassThru '
        - '-FilePath '

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
ScriptBlockTextmatch
  • -FilePath
  • -PassThru
  • Start-Process
  • saps
field:"ScriptBlockText" kind:match