name: Malicious PowerShell Process - Encoded Command
id: c4db14d9-7909-48b4-a054-aa14d89dbb19
version: 14
date: '2025-05-02'
author: David Dorsey, Michael Haag, Splunk, SirDuckly, GitHub Community
status: production
type: Hunting
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 is 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.
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 from datamodel=Endpoint.Processes where `process_powershell` 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)` | where match(process,\"(?i)[\\-|\\/|\u2013\
  |\u2014|\u2015][Ee^]{1,2}[NnCcOoDdEeMmAa^]+\\s+[\\\"]?[A-Za-z0-9+/=]{5,}[\\\"]?\"\
  ) | `malicious_powershell_process___encoded_command_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 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: System administrators may use this option, but it's not common.
references:
- https://regexr.com/662ov
- https://github.com/redcanaryco/AtomicTestHarnesses/blob/master/Windows/TestHarnesses/T1059.001_PowerShell/OutPowerShellCommandLineParameter.ps1
- https://ss64.com/ps/powershell.html
- https://twitter.com/M_haggis/status/1440758396534214658?s=20
- https://www.microsoft.com/security/blog/2022/01/15/destructive-malware-targeting-ukrainian-organizations/
- https://www.microsoft.com/en-us/security/blog/2023/05/24/volt-typhoon-targets-us-critical-infrastructure-with-living-off-the-land-techniques/
tags:
  analytic_story:
  - CISA AA22-320A
  - Hermetic Wiper
  - Sandworm Tools
  - Qakbot
  - Volt Typhoon
  - NOBELIUM Group
  - Data Destruction
  - Lumma Stealer
  - Malicious PowerShell
  - DarkCrystal RAT
  - WhisperGate
  - Crypto Stealer
  asset_type: Endpoint
  mitre_attack_id:
  - T1027
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1027/atomic_red_team/windows-sysmon.log
    source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
    sourcetype: XmlWinEventLog