Windows New Deny Permission Set On Service SD Via Sc.EXE

name: Windows New Deny Permission Set On Service SD Via Sc.EXE
id: d0f6a5e5-dbfd-46e1-8bd5-2e2905947c33
version: 11
creation_date: '2024-12-06'
modification_date: '2026-05-13'
author: Nasreddine Bencherchali, Michael Haag, Splunk
status: production
type: Anomaly
description: |
    The following analytic detects changes in a service security descriptor where a new deny ace has been added.
    It leverages data from Endpoint Detection and Response (EDR) agents, specifically searching for any process execution involving the "sc.exe" binary with the "sdset" flag targeting any service and adding a dedicated deny ace to specific groups.
    If confirmed malicious, this could allow an attacker to escalate their privileges, blind defenses and more.
    Investigate appropariate services and groups to determine if the behavior is malicious.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: |-
    | tstats `security_content_summariesonly`
      count min(_time) as firstTime
            max(_time) as lastTime
            values(Processes.process) as process
    FROM datamodel=Endpoint.Processes WHERE
    (
        Processes.process_name=sc.exe
        OR
        Processes.original_file_name=sc.exe
    )
    Processes.process="*sdset *"
    Processes.process="*(D;*"
    Processes.process IN (
        "*;IU*",
        "*;S-1-5-4*",
        "*;SU*",
        "*;S-1-5-6*",
        "*;BA*",
        "*;S-1-5-32-544*",
        "*;SY*",
        "*;S-1-5-18*",
        "*;WD*",
        "*;S-1-1-0*",
        "*;AU*",
        "*;S-1-5-11*",
        "*;LS*",
        "*;S-1-5-19*"
    )
    NOT Processes.process IN (
        "*macmnsvc*",
        "*masvc*",
        "*McAfeeFramework*",
        "*mfefire*",
        "*mfemms*",
        "*mfevtp*",
    )
    BY Processes.action Processes.dest Processes.original_file_name
       Processes.parent_process Processes.parent_process_exec
       Processes.parent_process_guid Processes.parent_process_id
       Processes.parent_process_name Processes.parent_process_path
       Processes.process Processes.process_exec Processes.process_guid
       Processes.process_hash Processes.process_id Processes.process_integrity_level
       Processes.process_name Processes.process_path Processes.user
       Processes.user_id Processes.vendor_product
    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_new_deny_permission_set_on_service_sd_via_sc_exe_filter`
how_to_implement: |-
    The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process name, and process original file name. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: |
    - McAfee related services changes are a known false positive. The sc.exe utility is used to deny groups such as Authenticated Users, Built-in Administrators and System access to certain permissions.
references:
    - https://www.sans.org/blog/red-team-tactics-hiding-windows-services/
    - https://news.sophos.com/wp-content/uploads/2020/06/glupteba_final-1.pdf
    - https://attack.mitre.org/techniques/T1564/
drilldown_searches:
    - name: View the detection results for - "$user$" and "$dest$"
      search: '%original_detection_search% | search  user = "$user$" dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$user$" and "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$", "$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
intermediate_findings:
    entities:
        - field: user
          type: user
          score: 20
          message: An instance of $parent_process_name$ spawning $process_name$ was identified attempting to disable security services on endpoint $dest$ by user $user$.
        - field: dest
          type: system
          score: 20
          message: An instance of $parent_process_name$ spawning $process_name$ was identified attempting to disable security services on endpoint $dest$ by user $user$.
threat_objects:
    - field: process_name
      type: process_name
analytic_story:
    - Defense Evasion or Unauthorized Access Via SDDL Tampering
asset_type: Endpoint
mitre_attack_id:
    - T1564
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1564/sc_sdset_tampering/sc_sdset_tampering_sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit