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Description

The following analytic detects the creation of files without extensions in critical folders like "System32\Drivers." It leverages data from the Endpoint.Filesystem datamodel, focusing on file paths and creation times. This activity is significant as it may indicate the presence of destructive malware, such as HermeticWiper, which drops driver components in these directories. If confirmed malicious, this behavior could lead to severe system compromise, including boot sector wiping, resulting in potential data loss and system inoperability.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2024-05-22
  • Author: Teoderick Contreras, Bhavin Patel, Splunk
  • ID: 0dbcac64-963c-11ec-bf04-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1485 Data Destruction Impact
Kill Chain Phase
  • Actions On Objectives
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Filesystem where Filesystem.file_path IN ("*\\System32\\drivers\\*", "*\\syswow64\\drivers\\*") by _time span=5m Filesystem.dest Filesystem.user Filesystem.file_name Filesystem.file_path Filesystem.process_guid Filesystem.file_create_time 
| `drop_dm_object_name(Filesystem)` 
| rex field="file_name" "\.(?<extension>[^\.]*$)" 
| where isnull(extension) 
| join process_guid [
| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes by _time span=5m Processes.process_name Processes.dest Processes.process_guid Processes.user 
| `drop_dm_object_name(Processes)`] 
| stats count min(_time) as firstTime max(_time) as lastTime by dest process_name process_guid file_name file_path file_create_time user 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_file_without_extension_in_critical_folder_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_file_without_extension_in_critical_folder_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
  • Filesystem.file_create_time
  • Filesystem.process_id
  • Filesystem.file_name
  • Filesystem.user
  • Filesystem.file_path
  • Filesystem.dest
  • Processes.process_name
  • Processes.dest
  • Processes.process_guid
  • Processes.user

How To Implement

To successfully implement this search you need to be ingesting information on process that include the name of the Filesystem responsible for the changes from your endpoints into the Endpoint datamodel in the Filesystem node.

Known False Positives

Unknown at this point

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
90.0 90 100 Driver file with out file extension drop in $file_path$ in $dest$

: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