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Description

The following analytic utilizes PowerShell Script Block Logging (EventCode=4104) to identify suspicious PowerShell execution. Script Block Logging captures the command sent to PowerShell, the full command to be executed. Upon enabling, logs will output to Windows event logs. Dependent upon volume, enable on critical endpoints or all.
This analytic identifies Get-ForestTrust from PowerSploit in order to gather domain trust information.
During triage, review parallel processes using an EDR product or 4688 events. It will be important to understand the timeline of events around this activity. Review the entire logged PowerShell script block.

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

  • Last Updated: 2021-09-02
  • Author: Michael Haag, Splunk
  • ID: 70fac80e-0bf1-11ec-9ba0-acde48001122

Annotations

ATT&CK
ID Technique Tactic
T1482 Domain Trust Discovery Discovery
Kill Chain Phase
  • Reconnaissance
NIST
CIS20
CVE
1
2
3
4
5
`powershell` EventCode=4104 ScriptBlockText = "*get-foresttrust*" 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer user_id 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `get_foresttrust_with_powershell_script_block_filter`

Macros

The SPL above uses the following Macros:

Note that get-foresttrust_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 field

  • _time
  • EventCode
  • Message
  • Path
  • OpCode
  • 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 here https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.

Known False Positives

False positives may be present. Tune as needed.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
12.0 30 40 Suspicious PowerShell Get-ForestTrust was identified on endpoint $ComputerName$ by user $User$.

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

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