PowerShell Script Evidence Eraser Searching for cleanLL and usersfiles.war

Identifies PowerShell script blocks containing evidence-cleanup indicators and a repeating while(1) loop.

FreeReviewedSigma · High · v5

Product: windows
Category: ps_script
Author: Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2023-11-09
Updated: 2026-07-31

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 matches PowerShell script content that appears to automate evidence removal, including strings and commands for cleaning files and targeting items like usersfiles.war and SysAidServer. Such behavior matters because attackers often use scripts to delete artifacts and disrupt forensic evidence on compromised hosts. Detection relies on Windows PowerShell script block telemetry where the script text contains all of the specified substrings, indicating the same erase-style routine.

Reporting behind it

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PowerShell Script Evidence Eraser Searching for cleanLL and usersfiles.war

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-evidence-cleanup-script-with-cleanll-and-while-1-loop-b377ddab

title: PowerShell Script Evidence Eraser Searching for cleanLL and usersfiles.war
id: f6794ad8-42be-457c-8e72-13465a1585d4
status: test
description: This rule matches PowerShell script content that appears to automate evidence removal, including strings and commands for cleaning files and targeting items like usersfiles.war and SysAidServer. Such behavior matters because attackers often use scripts to delete artifacts and disrupt forensic evidence on compromised hosts. Detection relies on Windows PowerShell script block telemetry where the script text contains all of the specified substrings, indicating the same erase-style routine.
references:
  - https://www.sysaid.com/blog/service-desk/on-premise-software-security-vulnerability-notification
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2023/TA/Lace-Tempest/posh_ps_apt_lace_tempest_eraser_script.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2023-11-09
tags:
  - attack.execution
  - attack.t1059.001
  - detection.emerging-threats
logsource:
  product: windows
  category: ps_script
  definition: "Requirements: Script Block Logging must be enabled"
detection:
  selection:
    ScriptBlockText|contains|all:
      - cleanLL
      - usersfiles.war
      - Remove-Item -Path "$tomcat_dir
      - SysAidServer
      - "sleep "
      - while(1)
  condition: selection
falsepositives:
  - Unlikely
level: high
license: DRL-1.1
related:
  - id: b377ddab-502d-4519-9e8c-5590033d2d70
    type: derived

Convert

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

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