Sysmon Driver Unloaded Via Fltmc.EXE

Status: test
Severity: high
Log source: category process_creation, product windows
Author: Kirill Kiryanov, oscd.community
Source: github.com/SigmaHQ/sigma

Detects possible Sysmon filter driver unloaded via fltmc.exe

Known false positives

Unlikely

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1070` Indicator Removal
Defense Impairment	`T1685.001` Disable or Modify Tools: Disable or Modify Windows Event Log

Telemetry coverage

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

Rule body

title: Sysmon Driver Unloaded Via Fltmc.EXE
id: 4d7cda18-1b12-4e52-b45c-d28653210df8
related:
    - id: 4931188c-178e-4ee7-a348-39e8a7a56821 # Generic
      type: similar
status: test
description: Detects possible Sysmon filter driver unloaded via fltmc.exe
references:
    - https://www.darkoperator.com/blog/2018/10/5/operating-offensively-against-sysmon
author: Kirill Kiryanov, oscd.community
date: 2019-10-23
modified: 2023-02-13
tags:
    - attack.stealth
    - attack.defense-impairment
    - attack.t1070
    - attack.t1685
    - attack.t1685.001
logsource:
    product: windows
    category: process_creation
detection:
    selection_img:
        - Image|endswith: '\fltMC.exe'
        - OriginalFileName: 'fltMC.exe'
    selection_cli:
        CommandLine|contains|all:
            - 'unload'
            - 'sysmon'
    condition: all of selection_*
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_img`

selection_img:
    - Image|endswith: '\fltMC.exe'
    - OriginalFileName: 'fltMC.exe'

Stage 2: `selection_cli`

selection_cli:
    CommandLine|contains|all:
        - 'unload'
        - 'sysmon'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`sysmon` corpus 4 (sigma 3, elastic 1) `unload` corpus 5 (sigma 4, splunk 1)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\fltMC.exe` corpus 3 (sigma 3)	`field:"Image" kind:ends_with value:"\fltMC.exe"`
`OriginalFileName`	eq	`fltMC.exe` corpus 3 (sigma 2, elastic 1)	`field:"OriginalFileName" kind:eq value:"fltMC.exe"`

Sysmon Driver Unloaded Via Fltmc.EXE

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection_img

Stage 2: selection_cli

Indicators

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli`