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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 PowerShell cmdlet - get-localgroup being ran. Typically, by itself, is not malicious but may raise suspicion based on time of day, endpoint and username.
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: Hunting
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2021-09-14
  • Author: Michael Haag, Splunk
  • ID: d7c6ad22-155c-11ec-bb64-acde48001122

Annotations

ATT&CK
ID Technique Tactic
T1069 Permission Groups Discovery Discovery
T1069.001 Local Groups Discovery
Kill Chain Phase
  • Reconnaissance
NIST
CIS20
CVE
1
2
3
4
5
`powershell` EventCode=4104 Message = "*get-localgroup*" 
| stats count min(_time) as firstTime max(_time) as lastTime by Message OpCode ComputerName User EventCode
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `powershell_get_localgroup_discovery_with_script_block_logging_filter`

Macros

The SPL above uses the following Macros:

Note that powershell_get_localgroup_discovery_with_script_block_logging_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
  • 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
15.0 30 50 Local group discovery on $dest$ by $user$.

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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