name: Malicious PowerShell Process - Encoded Command
id: c4db14d9-7909-48b4-a054-aa14d89dbb19
version: 7
date: '2022-01-18'
author: David Dorsey, Michael Haag, Splunk
status: production
type: Hunting
description: 'The following analytic identifies the use of the EncodedCommand PowerShell
  parameter. This is typically used by Administrators to run complex scripts, but
  commonly used by adversaries to hide their code. 

  The analytic identifies all variations of EncodedCommand, as PowerShell allows the
  ability to shorten the parameter. For example enc, enco, encod and so forth. In
  addition, through our research it was identified that PowerShell will interpret
  different command switch types beyond the hyphen. We have added endash, emdash,
  horizontal bar, and forward slash. 

  During triage, review parallel events to determine legitimacy. Tune as needed based
  on admin scripts in use. 

  Alternatively, may use regex per matching here https://regexr.com/662ov.'
data_source:
- Sysmon Event ID 1
search:
  selection1:
    OriginalFileName: pwsh.dll
  selection2:
    Image|endswith:
    - pwsh.exe
    - sqlps.exe
    - sqltoolsps.exe
    - powershell.exe
    - powershell_ise.exe
  selection3:
    OriginalFileName: PowerShell.EXE
  selection4:
    OriginalFileName: powershell_ise.EXE
  condition: (selection1 or selection2 or selection3 or selection4)
how_to_implement: To successfully implement this search you need to be ingesting information
  on process that include the name of the process responsible for the changes from
  your endpoints into the `Endpoint` datamodel in the `Processes` node. In addition,
  confirm the latest CIM App 4.20 or higher is installed and the latest TA for the
  endpoint product.
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/
tags:
  analytic_story:
  - Hermetic Wiper
  - Malicious PowerShell
  - NOBELIUM Group
  - WhisperGate
  - DarkCrystal RAT
  - Qakbot
  - CISA AA22-320A
  asset_type: Endpoint
  confidence: 50
  impact: 70
  message: Powershell.exe running potentially malicious encodede commands on $dest$
  mitre_attack_id:
  - T1027
  observable:
  - name: dest
    type: Endpoint
    role:
    - Victim
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  risk_score: 35
  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