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Description

The fsutil.exe application is a legitimate Windows utility used to perform tasks related to the file allocation table (FAT) and NTFS file systems. The update sequence number (USN) change journal provides a log of all changes made to the files on the disk. This search looks for fsutil.exe deleting the USN journal.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2018-12-03
  • Author: David Dorsey, Splunk
  • ID: b6e0ff70-b122-4227-9368-4cf322ab43c3

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1070 Indicator Removal on Host Defense Evasion
Kill Chain Phase
  • Actions on Objectives
NIST
  • DE.CM
  • PR.PT
  • DE.AE
  • DE.DP
  • PR.IP
CIS20
  • CIS 6
  • CIS 8
  • CIS 10
CVE
1
2
3
4
5
6
7
| tstats `security_content_summariesonly` count values(Processes.process) as process values(Processes.parent_process) as parent_process min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name=fsutil.exe by Processes.user Processes.process_name Processes.parent_process_name Processes.dest  
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)` 
| search process="*deletejournal*" AND process="*usn*" 
| `usn_journal_deletion_filter`

Macros

The SPL above uses the following Macros:

:information_source: usn_journal_deletion_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • Processes.process
  • Processes.parent_process
  • Processes.process_name
  • Processes.user
  • Processes.parent_process_name
  • Processes.dest

How To Implement

You must be ingesting data that records process activity from your hosts to populate the Endpoint data model in the Processes node. You must also be ingesting logs with both the process name and command line from your endpoints. The command-line arguments are mapped to the "process" field in the Endpoint data model.

Known False Positives

None identified

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
45.0 50 90 Possible USN journal deletion on $dest$

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

source | version: 2