Detection rules › Splunk

Get-ForestTrust with PowerShell Script Block

Status
production
Severity
medium
Group by
Guid, Name, Opcode, Path, ScriptBlockId, ScriptBlockText, dest, process_id, signature, signature_id, user_id, vendor_product
Author
Michael Haag, Splunk
Source
github.com/splunk/security_content

The following analytic detects the execution of the Get-ForestTrust command from PowerSploit using PowerShell Script Block Logging (EventCode=4104). This method captures the full command sent to PowerShell, providing detailed visibility into potentially suspicious activities. Monitoring this behavior is crucial as it can indicate an attempt to gather domain trust information, which is often a precursor to lateral movement or privilege escalation. If confirmed malicious, this activity could allow an attacker to map trust relationships within the domain, facilitating further exploitation and access to sensitive resources.

Known false positives

  • False positives may be present. Tune as needed.

MITRE ATT&CK coverage

Telemetry coverage

Rule body

name: Get-ForestTrust with PowerShell Script Block
id: 70fac80e-0bf1-11ec-9ba0-acde48001122
version: 12
creation_date: '2021-09-02'
modification_date: '2026-05-13'
author: Michael Haag, Splunk
status: production
type: TTP
description: The following analytic detects the execution of the Get-ForestTrust command from PowerSploit using PowerShell Script Block Logging (EventCode=4104). This method captures the full command sent to PowerShell, providing detailed visibility into potentially suspicious activities. Monitoring this behavior is crucial as it can indicate an attempt to gather domain trust information, which is often a precursor to lateral movement or privilege escalation. If confirmed malicious, this activity could allow an attacker to map trust relationships within the domain, facilitating further exploitation and access to sensitive resources.
data_source:
    - Powershell Script Block Logging 4104
search: |-
    `powershell` EventCode=4104 ScriptBlockText = "*get-foresttrust*"
      | fillnull
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY dest signature signature_id
           user_id vendor_product EventID
           Guid Opcode Name
           Path ProcessID ScriptBlockId
           ScriptBlockText
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `get_foresttrust_with_powershell_script_block_filter`
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://help.splunk.com/en/security-offerings/splunk-user-behavior-analytics/get-data-in/5.4.1/add-other-data-to-splunk-uba/configure-powershell-logging-to-see-powershell-anomalies-in-splunk-uba.
known_false_positives: False positives may be present. Tune as needed.
references:
    - https://powersploit.readthedocs.io/en/latest/Recon/Get-ForestTrust/
    - https://www.splunk.com/en_us/blog/security/hunting-for-malicious-powershell-using-script-block-logging.html
finding:
    title: Suspicious PowerShell Get-ForestTrust was identified on endpoint $dest$ by user $user_id$.
    entity:
        field: user_id
        type: user
        score: 50
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 50
          message: Suspicious PowerShell Get-ForestTrust was identified on endpoint $dest$ by user $user_id$.
analytic_story:
    - Active Directory Discovery
asset_type: Endpoint
mitre_attack_id:
    - T1482
    - T1059.001
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint

Stages and Predicates

Stage 1: search

`powershell` EventCode=4104 ScriptBlockText = "*get-foresttrust*"

Stage 2: fillnull

| fillnull

Stage 3: stats

| stats count min(_time) as firstTime max(_time) as lastTime
    BY dest signature signature_id
       user_id vendor_product EventID
       Guid Opcode Name
       Path ProcessID ScriptBlockId
       ScriptBlockText

Stage 4: search

| `security_content_ctime(firstTime)`

Stage 5: search

| `security_content_ctime(lastTime)`

Stage 6: search

| `get_foresttrust_with_powershell_script_block_filter`

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
EventCodeeq
  • 4104 corpus 269 (splunk 269)
field:"EventID" kind:eq value:"4104"
ScriptBlockTexteq
  • "*get-foresttrust*"
field:"ScriptBlockText" kind:eq