Suspicious Service DACL Modification Via Set-Service Cmdlet — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2022-10-18 / not supplied.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 8ee59c99fe169a4661c2a07f1a268c174234b090640f3e0a8c6021fd848c1c01

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Suspicious Service DACL Modification Via Set-Service Cmdlet
id: a95b9b42-1308-4735-a1af-abb1c5e6f5ac
related:
    - id: 99cf1e02-00fb-4c0d-8375-563f978dfd37
      type: derived
status: test
description: Detects suspicious DACL modifications via the "Set-Service" cmdlet using the "SecurityDescriptorSddl" flag (Only available with PowerShell 7) that can be used to hide services or make them unstopable
references:
    - https://www.sans.org/blog/red-team-tactics-hiding-windows-services/
    - https://learn.microsoft.com/pt-br/windows/win32/secauthz/sid-strings
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-10-18
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.t1543.003
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\pwsh.exe'
        - OriginalFileName: 'pwsh.dll'
    selection_sddl_flag:
        CommandLine|contains:
            - '-SecurityDescriptorSddl '
            - '-sd '
    selection_set_service:
        CommandLine|contains|all:
            - 'Set-Service '
            - 'D;;'
        CommandLine|contains:
            - ';;;IU'
            - ';;;SU'
            - ';;;BA'
            - ';;;SY'
            - ';;;WD'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://www.sans.org/blog/red-team-tactics-hiding-windows-services/
• https://learn.microsoft.com/pt-br/windows/win32/secauthz/sid-strings