Detection: Windows New Service Security Descriptor Set Via Sc.EXE

Description

The following analytic detects changes in a service security descriptor. 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. This behavior can be legitimate, such as when a user or administrator is configuring a service's security settings. Investigate appropariate services to determine if the behavior is malicious. If confirmed malicious, this could allow an attacker to escalate their privileges, blind defenses and more.

Search

 1
 2| tstats `security_content_summariesonly`
 3  count min(_time) as firstTime
 4        max(_time) as lastTime
 5        values(Processes.process) as process
 6
 7FROM datamodel=Endpoint.Processes WHERE
 8(
 9    Processes.process_name=sc.exe
10    OR
11    Processes.original_file_name=sc.exe
12)
13Processes.process="*sdset *"
14BY Processes.action Processes.dest Processes.original_file_name
15   Processes.parent_process Processes.parent_process_exec
16   Processes.parent_process_guid Processes.parent_process_id
17   Processes.parent_process_name Processes.parent_process_path
18   Processes.process Processes.process_exec Processes.process_guid
19   Processes.process_hash Processes.process_id Processes.process_integrity_level
20   Processes.process_name Processes.process_path Processes.user
21   Processes.user_id Processes.vendor_product
22
23| `drop_dm_object_name(Processes)`
24
25| `security_content_ctime(firstTime)`
26
27| `security_content_ctime(lastTime)`
28
29| `windows_new_service_security_descriptor_set_via_sc_exe_filter`

Data Source

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

Macros Used

Annotations

Default Configuration

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

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

• False positives are expected from legitimate system administrator scripts or installation utilities. Filter known parent image and commandline combinations.

Associated Analytic Story

• Defense Evasion or Unauthorized Access Via SDDL Tampering

Risk Based Analytics (RBA)

Risk Message:

An instance of $parent_process_name$ spawning $process_name$ was identified attempting to change the security descriptor of a service on endpoint $dest$ by user $user$.

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/

Detection Testing

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: 8