Detection: Malicious PowerShell Process - Encoded Command

Updated Date: 2026-03-25 ID: c4db14d9-7909-48b4-a054-aa14d89dbb19 Author: David Dorsey, Michael Haag, Splunk, SirDuckly, GitHub Community Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic detects the use of the EncodedCommand parameter in PowerShell processes. It leverages Endpoint Detection and Response (EDR) data to identify variations of the EncodedCommand parameter, including shortened forms and different command switch types. This activity can be significant because adversaries often use encoded commands to obfuscate malicious scripts, making detection harder. If confirmed malicious, this behavior could allow attackers to execute hidden code, potentially leading to unauthorized access, privilege escalation, or persistent threats within the environment. Review parallel events to determine legitimacy and tune based on known administrative scripts.

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`
 7by Processes.action Processes.dest Processes.original_file_name
 8   Processes.parent_process Processes.parent_process_exec
 9   Processes.parent_process_guid Processes.parent_process_id
10   Processes.parent_process_name Processes.parent_process_path
11   Processes.process Processes.process_exec Processes.process_guid
12   Processes.process_hash Processes.process_id
13   Processes.process_integrity_level Processes.process_name
14   Processes.process_path Processes.user
15   Processes.user_id Processes.vendor_product
16
17| `drop_dm_object_name(Processes)`
18
19| `security_content_ctime(firstTime)`
20
21| `security_content_ctime(lastTime)`
22
23| where match(process,"(?i)(?:^
24|\\s)(?:/(?!/)
25|--?
26|–{1,2}
27|—{1,2}
28|―{1,2})(?:ec
29|encodedcommand
30|encodedcomman
31|encodedcomma
32|encodedcomm
33|encodedcom
34|encodedco
35|encodedc
36|encoded
37|encode
38|encod
39|enco
40|enc
41|en
42|e(?=\\s))\\s+['\\\"]?[A-Za-z0-9+/=]{5,}['\\\"]?")
43
44| `malicious_powershell_process___encoded_command_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

Name	Value
process_powershell	`(Processes.process_name=pwsh.exe OR Processes.process_name=powershell.exe OR Processes.original_file_name=pwsh.dll OR Processes.original_file_name=PowerShell.EXE)`
malicious_powershell_process___encoded_command_filter	`search *`

malicious_powershell_process___encoded_command_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
T1027	Obfuscated Files or Information	Defense Evasion

Exploitation

DE.AE

CIS 10

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 Risk Event	False

This configuration file applies to all detections of type hunting.

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

False positives are expected from legitimate PowerShell scripts, system administrators, and applications. Filter as needed.

Associated Analytic Story

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: 20