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Detection rules › Sigma

Fsutil Suspicious Invocation

Status
stable
Severity
high
Log source
product windows, category process_creation
Author
Ecco, E.M. Anhaus, oscd.community
Source
github.com/SigmaHQ/sigma

Detects suspicious parameters of fsutil (deleting USN journal, configuring it with small size, etc). Might be used by ransomwares during the attack (seen by NotPetya and others).

MITRE ATT&CK coverage

TacticTechniques
StealthT1070 Indicator Removal
ImpactT1485 Data Destruction

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: Fsutil Suspicious Invocation
id: add64136-62e5-48ea-807e-88638d02df1e
status: stable
description: |
  Detects suspicious parameters of fsutil (deleting USN journal, configuring it with small size, etc).
  Might be used by ransomwares during the attack (seen by NotPetya and others).
references:
    - https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/fsutil-usn
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1070/T1070.md
    - https://eqllib.readthedocs.io/en/latest/analytics/c91f422a-5214-4b17-8664-c5fcf115c0a2.html
    - https://github.com/albertzsigovits/malware-notes/blob/558898932c1579ff589290092a2c8febefc3a4c9/Ransomware/Lockbit.md
    - https://blog.cluster25.duskrise.com/2023/05/22/back-in-black-blackbyte-nt
author: Ecco, E.M. Anhaus, oscd.community
date: 2019-09-26
modified: 2023-09-09
tags:
    - attack.impact
    - attack.stealth
    - attack.t1070
    - attack.t1485
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\fsutil.exe'
        - OriginalFileName: 'fsutil.exe'
    selection_cli:
        CommandLine|contains:
            - 'deletejournal'        # usn deletejournal ==> generally ransomware or attacker
            - 'createjournal'        # usn createjournal ==> can modify config to set it to a tiny size
            - 'setZeroData'          # file setZeroData  ==> empties a file with zeroes
    condition: all of selection_*
falsepositives:
    - Admin activity
    - Scripts and administrative tools used in the monitored environment
level: high

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_img

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

Stage 2: selection_cli

selection_cli:
    CommandLine|contains:
        - 'deletejournal'
        - 'createjournal'
        - 'setZeroData'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CommandLinematch
  • createjournal
  • deletejournal corpus 2 (sigma 1, splunk 1)
  • setZeroData corpus 2 (sigma 1, splunk 1)
Imageends_with
  • \fsutil.exe corpus 5 (sigma 5)
OriginalFileNameeq
  • fsutil.exe corpus 6 (sigma 2, elastic 2, splunk 2)