Sysmon Configuration Update

Status: test
Severity: medium
Log source: category process_creation, product windows
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects updates to Sysmon's configuration. Attackers might update or replace the Sysmon configuration with a bare bone one to avoid monitoring without shutting down the service completely

Known false positives

Legitimate administrators might use this command to update Sysmon configuration.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Impairment	`T1685` Disable or Modify Tools

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: Sysmon Configuration Update
id: 87911521-7098-470b-a459-9a57fc80bdfd
status: test
description: Detects updates to Sysmon's configuration. Attackers might update or replace the Sysmon configuration with a bare bone one to avoid monitoring without shutting down the service completely
references:
    - https://learn.microsoft.com/en-us/sysinternals/downloads/sysmon
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-03-09
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: '-c'
    condition: all of selection_*
falsepositives:
    - Legitimate administrators might use this command to update Sysmon configuration.
level: medium

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_pe`

selection_pe:
    - Image|endswith:
          - \Sysmon64.exe
          - \Sysmon64a.exe
          - \Sysmon.exe
    - Description: 'System activity monitor'

Stage 2: `selection_cli`

selection_cli:
    CommandLine|contains|windash: '-c'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`-c` transforms: `windash` corpus 7 (sigma 6, splunk 1)	`field:"CommandLine" kind:match value:"-c"`
`Description`	eq	`System activity monitor` corpus 2 (sigma 2)	`field:"Description" kind:eq value:"System activity monitor"`
`Image`	ends_with	`\Sysmon.exe` corpus 3 (sigma 3) `\Sysmon64.exe` corpus 3 (sigma 3) `\Sysmon64a.exe` corpus 3 (sigma 3)	`field:"Image" kind:ends_with`