Windows Information Discovery Fsutil

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Description

The following analytic identifies a process execution of Windows OS built-in tool FSUTIL to discover file system information. This tool is being abused or used by several adversaries or threat actor to query/list all drives, drive type, volume information or volume statistics by using the FSINFO parameter of this tool. This technique was seen in WINPEAS post exploitation tool that is being used by ransomware prestige to gain privilege and persistence to the targeted host.

• Type: Hunting
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2022-11-30
• Author: Teoderick Contreras, Splunk
• ID: 2181f261-93e6-4166-a5a9-47deac58feff

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1082	System Information Discovery	Discovery

Kill Chain Phase

• Exploitation

NIST

• DE.AE

CIS20

• CIS 10

CVE

Search

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name="fsutil.exe" OR Processes.original_file_name = "fsutil.exe" AND Processes.process = "*fsinfo*" by Processes.process_name Processes.original_file_name Processes.process Processes.process_id Processes.process_guid Processes.parent_process_name Processes.parent_process Processes.parent_process_guid Processes.dest Processes.user 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_information_discovery_fsutil_filter`

Macros

The SPL above uses the following Macros:

• security_content_ctime
• security_content_summariesonly

windows_information_discovery_fsutil_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.dest
• Processes.user
• Processes.parent_process_name
• Processes.parent_process
• Processes.original_file_name
• Processes.process_name
• Processes.process
• Processes.process_id
• Processes.parent_process_path
• Processes.process_path
• Processes.parent_process_id
• Processes.parent_process_guid
• Processes.process_guid

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Tune and filter known instances of wermgr.exe may be used.

Known False Positives

unknown

Associated Analytic Story

• Windows Post-Exploitation
• Prestige Ransomware

RBA

Risk Score	Impact	Confidence	Message
9.0	30	30	process $process_name$ with commandline $process$ is executed in $dest$

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

• https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/fsutil
• https://github.com/carlospolop/PEASS-ng/tree/master/winPEAS
• https://www.microsoft.com/en-us/security/blog/2022/10/14/new-prestige-ransomware-impacts-organizations-in-ukraine-and-poland/

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

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