Potential Suspicious PowerShell Keywords — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems), Perez Diego (@darkquassar), Tuan Le (NCSGroup). Source status: test; severity: medium. Source dates: 2019-02-11 / 2023-04-21.

{
  "product": "windows",
  "category": "ps_script",
  "definition": "Requirements: Script Block Logging must be enabled"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 7c244db1a57ffbf421dafc586add2a1db765964d4fd6a08a99a9ce68da35b91e

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: Potential Suspicious PowerShell Keywords
id: 1f49f2ab-26bc-48b3-96cc-dcffbc93eadf
status: test
description: Detects potentially suspicious keywords that could indicate the use of a PowerShell exploitation framework
references:
    - https://posts.specterops.io/entering-a-covenant-net-command-and-control-e11038bcf462
    - https://github.com/PowerShellMafia/PowerSploit/blob/d943001a7defb5e0d1657085a77a0e78609be58f/CodeExecution/Invoke-ReflectivePEInjection.ps1
    - https://github.com/hlldz/Phant0m/blob/30c2935d8cf4aafda17ee2fab7cd0c4aa9a607c2/old/Invoke-Phant0m.ps1
    - https://gist.github.com/MHaggis/0dbe00ad401daa7137c81c99c268cfb7
author: Florian Roth (Nextron Systems), Perez Diego (@darkquassar), Tuan Le (NCSGroup)
date: 2019-02-11
modified: 2023-04-21
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection:
        ScriptBlockText|contains:
            - 'System.Reflection.Assembly.Load($'
            - '[System.Reflection.Assembly]::Load($'
            - '[Reflection.Assembly]::Load($'
            - 'System.Reflection.AssemblyName'
            - 'Reflection.Emit.AssemblyBuilderAccess'
            - 'Reflection.Emit.CustomAttributeBuilder'
            - 'Runtime.InteropServices.UnmanagedType'
            - 'Runtime.InteropServices.DllImportAttribute'
            - 'SuspendThread'
            - 'rundll32'
            # - 'FromBase64'
            # - 'Invoke-WMIMethod' # Prone to FP
            # - 'http://127.0.0.1' # Prone to FP
    condition: selection
falsepositives:
    - Unknown
level: medium

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://posts.specterops.io/entering-a-covenant-net-command-and-control-e11038bcf462
• https://github.com/PowerShellMafia/PowerSploit/blob/d943001a7defb5e0d1657085a77a0e78609be58f/CodeExecution/Invoke-ReflectivePEInjection.ps1
• https://github.com/hlldz/Phant0m/blob/30c2935d8cf4aafda17ee2fab7cd0c4aa9a607c2/old/Invoke-Phant0m.ps1
• https://gist.github.com/MHaggis/0dbe00ad401daa7137c81c99c268cfb7