Detection: Powershell Defender Threat Actions Set to Allow

Description

The following analytic detects the setting of the Windows Defender Threat Actions to allow. It leverages data from the Endpoint.Processes data model, specifically monitoring the execution of the Set-MpPreference cmdlet with the -HighThreatDefaultAction, -ModerateThreatDefaultAction, -LowThreatDefaultAction, and -SevereThreatDefaultAction parameters set to 6. This activity is significant because it is commonly used by malware such as RATs, bots, or Trojans to evade detection by allowing threats to pass through the Windows Defender antivirus engine. If confirmed malicious, this action could allow an attacker to execute malicious code without being detected by Windows Defender, leading to potential data exfiltration, further system compromise, or persistent access within the environment.

Search

 1
 2| tstats `security_content_summariesonly`
 3  count min(_time) as firstTime
 4        max(_time) as lastTime
 5from datamodel=Endpoint.Processes where
 6`process_powershell`
 7Processes.process="*Set-MpPreference*"
 8(
 9  Processes.process IN (
10    "*-HighThreatDefaultAction*",
11    "*-ModerateThreatDefaultAction*",
12    "*-LowThreatDefaultAction*",
13    "*-SevereThreatDefaultAction*"
14  )
15  Processes.process IN (
16    "* 6*"
17  )
18)
19by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
20   Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
21   Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec
22   Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level
23   Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product
24
25
26| `drop_dm_object_name(Processes)`
27
28| `security_content_ctime(firstTime)`
29
30| `security_content_ctime(lastTime)`
31
32| `powershell_defender_threat_actions_set_to_allow_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 GUID, process name, and parent process. 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

Limited false positives. However, tune based on scripts that may perform this action.

Associated Analytic Story

• Salat Stealer

Finding

References

• https://www.broadcom.com/support/security-center/protection-bulletin/uac-0252-activity-delivering-shadowsniff-and-salatstealer-malware

• https://bazaar.abuse.ch/browse/tag/SalatStealer/

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: 1