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

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2022-10-24 / not supplied.

{
  "product": "windows",
  "category": "ps_script",
  "definition": "Requirements: Script Block Logging must be enabled"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 3b3ae290dd173005c0e8f6e731505f56089faed3136dfec38be72bae99381b44

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 - PS
id: 22d80745-6f2c-46da-826b-77adaededd74
related:
    - id: a95b9b42-1308-4735-a1af-abb1c5e6f5ac
      type: similar
status: test
description: Detects usage of the "Set-Service" powershell cmdlet to configure a new SecurityDescriptor that allows a service to be hidden from other utilities such as "sc.exe", "Get-Service"...etc. (Works only in powershell 7)
references:
    - https://twitter.com/Alh4zr3d/status/1580925761996828672
    - https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.management/set-service?view=powershell-7.2
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-10-24
tags:
    - attack.persistence
    - attack.privilege-escalation
    - attack.execution
    - attack.stealth
    - attack.t1574.011
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection_sddl_flag:
        ScriptBlockText|contains:
            - '-SecurityDescriptorSddl '
            - '-sd '
    selection_set_service:
        ScriptBlockText|contains|all:
            - 'Set-Service '
            - 'D;;'
        ScriptBlockText|contains:
            - ';;;IU'
            - ';;;SU'
            - ';;;BA'
            - ';;;SY'
            - ';;;WD'
    condition: all of selection_*
falsepositives:
    - Rare intended use of hidden services
    - Rare FP could occur due to the non linearity of the ScriptBlockText log
level: high

Original YAML and metadata in JSON

False positives

• Rare intended use of hidden services
• Rare FP could occur due to the non linearity of the ScriptBlockText log

Source references

• https://twitter.com/Alh4zr3d/status/1580925761996828672
• https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.management/set-service?view=powershell-7.2