Potential In-Memory Execution Using Reflection.Assembly — Sigma Rule

Rule metadata and linked tags

Author: frack113. Source status: test; severity: medium. Source dates: 2022-12-25 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 0830b766775cf48e0f823ccaf568533be80884c698ac40e179e5d4e76963cd2b

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 In-Memory Execution Using Reflection.Assembly
id: ddcd88cb-7f62-4ce5-86f9-1704190feb0a
status: test
description: Detects usage of "Reflection.Assembly" load functions to dynamically load assemblies in memory
references:
    - https://speakerdeck.com/heirhabarov/hunting-for-powershell-abuse?slide=50
author: frack113
date: 2022-12-25
tags:
    - attack.stealth
    - attack.t1620
logsource:
    product: windows
    category: ps_script
    definition: Script Block Logging must be enable
detection:
    selection:
        ScriptBlockText|contains: '[Reflection.Assembly]::load'
    condition: selection
falsepositives:
    - Legitimate use of the library
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate use of the library

Source references

• https://speakerdeck.com/heirhabarov/hunting-for-powershell-abuse?slide=50