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Description

This analytic is to look for suspicious file creation in the critical folder like "System32\Drivers" folder without file extension. This artifacts was seen in latest hermeticwiper where it drops its driver component in Driver Directory both the compressed(without file extension) and the actual driver component (with .sys file extension). This TTP is really a good indication that a host might be compromised by this destructive malware that wipes the boot sector of the system.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2022-02-25
  • 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
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 3
  • CIS 5
  • CIS 16
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

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