Windows: Process creation event for Sysmon uninstall using Sysmon -u

Flags attempts to uninstall Sysmon on Windows by running Sysmon with the -u flag.

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windows-process-creation-event-for-sysmon-uninstall-using-sysmon-u-6a5f68d1

title: "Windows: Process creation event for Sysmon uninstall using Sysmon -u"
id: bc69366d-d800-43ff-921e-19cd0f6fb0c9
status: test
description: This rule identifies process executions where Sysmon binaries (Sysmon64.exe, Sysmon64a.exe, or Sysmon.exe) are started with the uninstall flag (-u). Uninstalling Sysmon can reduce visibility into host activity and may be used as defense impairment. It relies on Windows process creation telemetry, including the process image name, its description, and the command line contents.
references:
  - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1562.001/T1562.001.md#atomic-test-11---uninstall-sysmon
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_sysinternals_sysmon_uninstall.yml
author: frack113, Huntrule Team
date: 2022-01-12
modified: 2026-06-29
tags:
  - attack.defense-impairment
  - attack.t1685
logsource:
  category: process_creation
  product: windows
detection:
  selection_pe:
    - Image|endswith:
        - \Sysmon64.exe
        - \Sysmon64a.exe
        - \Sysmon.exe
    - Description: System activity monitor
  selection_cli:
    CommandLine|contains|windash: -u
  condition: all of selection_*
falsepositives:
  - Legitimate administrators might use this command to remove Sysmon for debugging purposes
level: high
license: DRL-1.1
related:
  - id: 6a5f68d1-c4b5-46b9-94ee-5324892ea939
    type: derived

What it detects

This rule identifies process executions where Sysmon binaries (Sysmon64.exe, Sysmon64a.exe, or Sysmon.exe) are started with the uninstall flag (-u). Uninstalling Sysmon can reduce visibility into host activity and may be used as defense impairment. It relies on Windows process creation telemetry, including the process image name, its description, and the command line contents.

Known false positives

Legitimate administrators might use this command to remove Sysmon for debugging purposes

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