Windows PowerShell Script Block Matching POWERTRASH Behavior Indicators

Detects PowerShell ScriptBlock text containing POWERTRASH-related in-memory and dynamic execution indicators on Windows.

FreeReviewedSigma · High · v5

Product: windows
Category: ps_script
Author: Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2023-05-04
Updated: 2026-07-31

Analysis Detection

ATT&CK techniques

Execution

Recon
Resource Dev
Initial Access
Execution
- T1059.001PowerShell
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags Windows PowerShell script content that includes a set of indicators commonly associated with dynamic in-memory execution patterns. Such behavior matters because attackers may embed and decode payloads (e.g., Base64), construct assemblies in memory, and invoke function pointers to run code without touching disk. The detection relies on telemetry that records PowerShell script block text and matches it against specific string components.

Reporting behind it

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Windows PowerShell Script Block Matching POWERTRASH Behavior Indicators

Pivot detection · T1059.001 · 9 related

Changelog

v5
Candidate ingested via manual entry.2026-07-31
v4
Candidate ingested via manual entry.2026-07-31
v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-powershell-scriptblock-execution-matching-powertrash-indicators-4e19528a

title: Windows PowerShell Script Block Matching POWERTRASH Behavior Indicators
id: 5e5b3183-5b43-430d-8c65-28e32b6b88b1
status: test
description: This rule flags Windows PowerShell script content that includes a set of indicators commonly associated with dynamic in-memory execution patterns. Such behavior matters because attackers may embed and decode payloads (e.g., Base64), construct assemblies in memory, and invoke function pointers to run code without touching disk. The detection relies on telemetry that records PowerShell script block text and matches it against specific string components.
references:
  - https://labs.withsecure.com/publications/fin7-target-veeam-servers
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2023/TA/FIN7/posh_ps_apt_fin7_powertrash_execution.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2023-05-04
tags:
  - attack.execution
  - attack.t1059.001
  - attack.g0046
  - detection.emerging-threats
logsource:
  product: windows
  category: ps_script
  definition: bade5735-5ab0-4aa7-a642-a11be0e40872
detection:
  selection:
    ScriptBlockText|contains|all:
      - IO.Compression.DeflateStream
      - IO.MemoryStream
      - ::FromBase64String
      - GetDelegateForFunctionPointer
      - .Invoke()
      - GlobalAssemblyCache
  condition: selection
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: 4e19528a-f081-40dd-be09-90c39352bd64
    type: derived

Convert

This rule as a query you can run. Uses no unlock credit.

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