name: Nishang PowershellTCPOneLine
id: 1a382c6c-7c2e-11eb-ac69-acde48001122
version: 2
date: '2021-03-03'
author: Michael Haag, Splunk
status: production
type: TTP
description: This query detects the Nishang Invoke-PowerShellTCPOneLine utility that
  spawns a call back to a remote Command And Control server. This is a powershell
  oneliner. In addition, this will capture on the command-line additional utilities
  used by Nishang. Triage the endpoint and identify any parallel processes that look
  suspicious. Review the reputation of the remote IP or domain contacted by the powershell
  process.
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
  selection5:
    CommandLine: '*System.Text.ASCIIEncoding*'
  selection6:
    CommandLine: '*Net.Sockets.TCPClient*'
  condition: (selection1 or selection2 or selection3 or selection4) and selection5
    and selection6
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: Limited false positives may be present. Filter as needed based
  on initial analysis.
references:
- https://github.com/samratashok/nishang/blob/master/Shells/Invoke-PowerShellTcpOneLine.ps1
- https://www.volexity.com/blog/2021/03/02/active-exploitation-of-microsoft-exchange-zero-day-vulnerabilities/
- https://www.microsoft.com/security/blog/2021/03/02/hafnium-targeting-exchange-servers/
- https://www.rapid7.com/blog/post/2021/03/03/rapid7s-insightidr-enables-detection-and-response-to-microsoft-exchange-0-day/
tags:
  analytic_story:
  - HAFNIUM Group
  asset_type: Endpoint
  confidence: 60
  impact: 70
  message: Possible Nishang Invoke-PowerShellTCPOneLine behavior on $dest$
  mitre_attack_id:
  - T1059
  - T1059.001
  observable:
  - name: dest
    type: Endpoint
    role:
    - Victim
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  risk_score: 42
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1059.001/atomic_red_team/windows-sysmon.log
    source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
    sourcetype: xmlwineventlog