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title	excerpt	categories	last_modified_at	toc	toc_label	tags
GetNetTcpconnection with PowerShell Script Block	System Network Connections Discovery	Endpoint	2021-09-10	true		System Network Connections Discovery Discovery Splunk Enterprise Splunk Enterprise Security Splunk Cloud Endpoint

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Description

The following analytic utilizes PowerShell Script Block Logging (EventCode=4104) to identify the execution of the Get-NetTcpconnection commandlet. This commandlet is used to return a listing of network connections on a compromised system. Red Teams and adversaries alike may use this commandlet for situational awareness and Active Directory Discovery.

• Type: Hunting
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2021-09-10
• Author: Mauricio Velazco, Splunk
• ID: 091712ff-b02a-4d43-82ed-34765515d95d

ATT&CK

ID	Technique	Tactic
T1049	System Network Connections Discovery	Discovery

Search

`powershell` EventCode=4104 (Message = "*Get-NetTcpconnection*") 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode Message ComputerName User 
| `security_content_ctime(firstTime)` 
| `getnettcpconnection_with_powershell_script_block_filter`

Associated Analytic Story

• Active Directory Discovery

How To Implement

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

Required field

• _time
• EventCode
• Message
• ComputerName
• User

Kill Chain Phase

• Reconnaissance

Known False Positives

Administrators or power users may use this PowerShell commandlet for troubleshooting.

RBA

Risk Score	Impact	Confidence	Message
15.0	30	50	Network Connection discovery on dest by user

Reference

• https://attack.mitre.org/techniques/T1049/
• https://docs.microsoft.com/en-us/powershell/module/nettcpip/get-nettcpconnection?view=windowsserver2019-ps

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

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1049/AD_discovery/windows-powershell.log

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