Windows Recovery Environment Disabled Via Reagentc — Sigma Rule

Rule metadata and linked tags

Author: Daniel Koifman (KoifSec), Michael Vilshin. Source status: experimental; severity: medium. Source dates: 2025-07-31 / not supplied.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 9d685dad1ea2864cfd81c7f300c177c6a18e003c8e3226a6a3683350a9982823

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: Windows Recovery Environment Disabled Via Reagentc
id: db1c21e4-cd66-4b4e-85ca-590f0780529c
status: experimental
description: |
    Detects attempts to disable windows recovery environment using Reagentc.
    ReAgentc.exe is a command-line tool in Windows used to manage the Windows Recovery Environment (WinRE).
    It allows users to enable, disable, and configure WinRE, which is used for troubleshooting and repairing common boot issues.
references:
    - https://www.elastic.co/security-labs/maas-appeal-an-infostealer-rises-from-the-ashes
    - https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/reagentc-command-line-options?view=windows-11
author: Daniel Koifman (KoifSec), Michael Vilshin
date: 2025-07-31
tags:
    - attack.impact
    - attack.t1490
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:   # Example command simulated:  reagentc /disable
        - Image|endswith: '\reagentc.exe'
        - OriginalFileName: 'reagentc.exe'
    selection_cli:
        CommandLine|contains|windash: '/disable'
    condition: all of selection_*
falsepositives:
    - Legitimate administrative activity
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate administrative activity

Source references

• https://www.elastic.co/security-labs/maas-appeal-an-infostealer-rises-from-the-ashes
• https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/reagentc-command-line-options?view=windows-11