Suspicious Service DACL Modification Via Set-Service Cmdlet

SIGMA detection rule by Nasreddine Bencherchali (Nextron Systems) · NOASSERTION

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

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

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

5345c3a8-7a7c-4659-994f-0cdd053e3f6a

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

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[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

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