Detection: Windows SubInAcl Execution

Updated Date: 2026-05-13 ID: 12491419-1a6f-4af4-afc3-4e2052f0610e Author: Nasreddine Bencherchali, Michael Haag, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects the execution of the SubInAcl utility. SubInAcl is a legacy Windows Resource Kit tool from the Windows 2003 era, used to manipulate security descriptors of securable objects. It leverages data from Endpoint Detection and Response (EDR) agents, specifically searching for any process execution involving "SubInAcl.exe" binary. This activity can be significant because the utility should be rarely found on modern Windows machines, which mean any execution could potentially be considered suspicious. If confirmed malicious, this could allow an attacker to blind defenses by tampering with EventLog ACLs or modifying the access to a previously denied resource.

Search

 1
 2| tstats `security_content_summariesonly` values(Processes.process) as process min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
 3  WHERE (
 4        Processes.process_name=subinacl.exe
 5        OR
 6        Processes.original_file_name=SubInAcl.exe
 7    )
 8  BY Processes.action Processes.dest Processes.original_file_name
 9     Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
10     Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
11     Processes.process Processes.process_exec Processes.process_guid
12     Processes.process_hash Processes.process_id Processes.process_integrity_level
13     Processes.process_name Processes.process_path Processes.user
14     Processes.user_id Processes.vendor_product
15
16| `drop_dm_object_name(Processes)`
17
18| `security_content_ctime(firstTime)`
19
20| `security_content_ctime(lastTime)`
21
22| `windows_subinacl_execution_filter`

Data Source

Name	Platform	Sourcetype	Source
Windows Event Log Security 4688	Windows	`'XmlWinEventLog'`	`'XmlWinEventLog:Security'`
Sysmon EventID 1	Windows	`'XmlWinEventLog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`
CrowdStrike ProcessRollup2	Other	`'crowdstrike:events:sensor'`	`'crowdstrike'`

Macros Used

Name	Value
security_content_summariesonly	`summariesonly=`summariesonly_config `allow_old_summaries=`oldsummaries_config `fillnull_value=`fillnull_config``
windows_subinacl_execution_filter	`search *`

windows_subinacl_execution_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1222.001	Windows Permissions	Defense Impairment

Exploitation

DE.AE

CIS 10

Wizard Spider

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Finding (Notable)	No
Creates Intermediate Finding (Risk Event)	Yes

Anomaly detections generate Intermediate Findings (Risk Events). They do not generate a Finding (Notable) directly.

Implementation

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

No false positives have been identified at this time. should be identified and understood.

Associated Analytic Story

Defense Evasion or Unauthorized Access Via SDDL Tampering

Intermediate Findings

Message	Entity Field	Entity Type	Risk Score
An instance of $parent_process_name$ spawning $process_name$ was identified attempting to disable security services on endpoint $dest$ by user $user$.	dest	system	20
An instance of $parent_process_name$ spawning $process_name$ was identified attempting to disable security services on endpoint $dest$ by user $user$.	user	user	20

Threat Objects

Field	Type
process_name	process_name

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 9