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Description

The following analytic utilizes PowerShell Script Block Logging (EventCode=4104) to identify the usage of the Enter-PSSession. This commandlet can be used to open an interactive session on a remote endpoint leveraging the WinRM protocol. Red Teams and adversaries alike may abuse WinRM and Enter-PSSession for lateral movement and remote code execution.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2022-03-22
  • Author: Mauricio Velazco, Splunk
  • ID: a4e8f3a4-48b2-11ec-bcfc-3e22fbd008af

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1021 Remote Services Lateral Movement
T1021.006 Windows Remote Management Lateral Movement
Kill Chain Phase
  • Exploitation
NIST
CIS20
CVE
1
2
3
4
5
`powershell` EventCode=4104 (ScriptBlockText="*Enter-PSSession*" AND ScriptBlockText="*-ComputerName*") 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer user_id 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `interactive_session_on_remote_endpoint_with_powershell_filter`

Macros

The SPL above uses the following Macros:

:information_source: interactive_session_on_remote_endpoint_with_powershell_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • EventCode
  • Message
  • ComputerName
  • User

How To Implement

To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup instructions can be found https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.

Known False Positives

Administrators may leverage WinRM and Enter-PSSession for administrative and troubleshooting tasks. This activity is usually limited to a small set of hosts or users. In certain environments, tuning may not be possible.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
45.0 90 50 An interactive session was opened on a remote endpoint from $ComputerName

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

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 | version: 3