Try in Splunk Security Cloud

Description

The following analytic detects the execution of the Get-NetTcpconnection PowerShell cmdlet using PowerShell Script Block Logging (EventCode=4104). This cmdlet lists network connections on a system, which adversaries may use for situational awareness and Active Directory discovery. Monitoring this activity is crucial as it can indicate reconnaissance efforts by an attacker. If confirmed malicious, this behavior could allow an attacker to map the network, identify critical systems, and plan further attacks, potentially leading to data exfiltration or lateral movement within the network.

  • Type: Hunting

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

  • Last Updated: 2024-05-22
  • Author: Mauricio Velazco, Splunk
  • ID: 091712ff-b02a-4d43-82ed-34765515d95d

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1049 System Network Connections Discovery Discovery
Kill Chain Phase
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


1
2
3
4



`powershell` EventCode=4104 (ScriptBlockText = "*Get-NetTcpconnection*") 
| stats count min(_time) as firstTime max(_time) as lastTime by Opcode Computer UserID EventCode ScriptBlockText 
| `security_content_ctime(firstTime)` 
| `getnettcpconnection_with_powershell_script_block_filter`

Macros

The SPL above uses the following Macros:

:information_source: getnettcpconnection_with_powershell_script_block_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
  • ScriptBlockText
  • Opcode
  • Computer
  • UserID
  • EventCode

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.

Known False Positives

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

Associated Analytic Story

RBA

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

: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