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Detection rules › Sigma

Potential In-Memory Execution Using Reflection.Assembly

Status
test
Severity
medium
Log source
category ps_script, product windows
Author
frack113
Source
github.com/SigmaHQ/sigma

Detects usage of "Reflection.Assembly" load functions to dynamically load assemblies in memory

Known false positives

  • Legitimate use of the library

MITRE ATT&CK coverage

TacticTechniques
Stealth

Telemetry coverage

ProviderRecord / event type
PowerShellEvent ID 4104: Creating Scriptblock text (MessageNumber of MessageTotal).

Rule body

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

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    ScriptBlockText|contains: '[Reflection.Assembly]::load'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
ScriptBlockTextmatch
  • [Reflection.Assembly]::load
field:"ScriptBlockText" kind:match value:"[Reflection.Assembly]::load"