Suspicious Get-Variable.exe Creation — Sigma Rule

Rule metadata and linked tags

Author: frack113. Source status: test; severity: high. Source dates: 2022-04-23 / not supplied.

{
  "product": "windows",
  "category": "file_event"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 5bb56d431ea95b81cc0e1e4dfc682d21753e6e265d565babfcbb7af4e6b77aa5

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Suspicious Get-Variable.exe Creation
id: 0c3fac91-5627-46e8-a6a8-a0d7b9b8ae1b
status: test
description: |
    Get-Variable is a valid PowerShell cmdlet
    WindowsApps is by default in the path where PowerShell is executed.
    So when the Get-Variable command is issued on PowerShell execution, the system first looks for the Get-Variable executable in the path and executes the malicious binary instead of looking for the PowerShell cmdlet.
references:
    - https://blog.malwarebytes.com/threat-intelligence/2022/04/colibri-loader-combines-task-scheduler-and-powershell-in-clever-persistence-technique/
    - https://www.joesandbox.com/analysis/465533/0/html
author: frack113
date: 2022-04-23
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.stealth
    - attack.t1546
    - attack.t1027
logsource:
    product: windows
    category: file_event
detection:
    selection:
        TargetFilename|endswith: 'Local\Microsoft\WindowsApps\Get-Variable.exe'
    condition: selection
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://blog.malwarebytes.com/threat-intelligence/2022/04/colibri-loader-combines-task-scheduler-and-powershell-in-clever-persistence-technique/
• https://www.joesandbox.com/analysis/465533/0/html