Service DACL Abuse To Hide Services Via Sc.EXE

Status: test
Severity: high
Log source: category process_creation, product windows
Author: Andreas Hunkeler (@Karneades)
Source: github.com/SigmaHQ/sigma

Detects usage of the "sc.exe" utility adding a new service with special permission seen used by threat actors which makes the service hidden and unremovable.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1574.011` Hijack Execution Flow: Services Registry Permissions Weakness
Stealth	`T1574.011` Hijack Execution Flow: Services Registry Permissions Weakness

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: Service DACL Abuse To Hide Services Via Sc.EXE
id: a537cfc3-4297-4789-92b5-345bfd845ad0
related:
    - id: 99cf1e02-00fb-4c0d-8375-563f978dfd37 # Deny Service Access
      type: similar
    - id: 98c5aeef-32d5-492f-b174-64a691896d25 # Generic SD tampering
      type: similar
status: test
description: Detects usage of the "sc.exe" utility adding a new service with special permission seen used by threat actors which makes the service hidden and unremovable.
references:
    - https://blog.talosintelligence.com/2021/10/threat-hunting-in-large-datasets-by.html
    - https://www.sans.org/blog/red-team-tactics-hiding-windows-services/
    - https://twitter.com/Alh4zr3d/status/1580925761996828672
    - https://itconnect.uw.edu/tools-services-support/it-systems-infrastructure/msinf/other-help/understanding-sddl-syntax/
author: Andreas Hunkeler (@Karneades)
date: 2021-12-20
modified: 2022-08-08
tags:
    - attack.persistence
    - attack.privilege-escalation
    - attack.execution
    - attack.stealth
    - attack.t1574.011
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\sc.exe'
        - OriginalFileName: 'sc.exe'
    selection_cli:
        CommandLine|contains|all:
            - 'sdset'
            # Summary of permissions
            #   DC: Delete All Child Objects
            #   LC: List Contents
            #   WP: Write All Properties
            #   DT: Delete Subtree
            #   SD: Delete
            - 'DCLCWPDTSD'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_img`

selection_img:
    - Image|endswith: '\sc.exe'
    - OriginalFileName: 'sc.exe'

Stage 2: `selection_cli`

selection_cli:
    CommandLine|contains|all:
        - 'sdset'
        - 'DCLCWPDTSD'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`DCLCWPDTSD` corpus 2 (sigma 2) `sdset` corpus 5 (sigma 5)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\sc.exe` corpus 30 (sigma 30)	`field:"Image" kind:ends_with value:"\sc.exe"`
`OriginalFileName`	eq	`sc.exe` corpus 30 (sigma 12, splunk 10, elastic 8)	`field:"OriginalFileName" kind:eq value:"sc.exe"`