Detection: Resize ShadowStorage volume

Description

The following analytic identifies the resizing of shadow storage volumes, a technique used by ransomware like CLOP to prevent the recreation of shadow volumes. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions involving "vssadmin.exe" with parameters related to resizing shadow storage. This activity is significant as it indicates an attempt to hinder recovery efforts by manipulating shadow copies. If confirmed malicious, this could lead to successful ransomware deployment, making data recovery difficult and increasing the potential for data loss.

Search

1
2| tstats `security_content_summariesonly` values(Processes.process) as cmdline values(Processes.parent_process_name) as parent_process values(Processes.process_name) as process_name min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name = "cmd.exe" OR Processes.parent_process_name = "powershell.exe" OR Processes.parent_process_name = "powershell_ise.exe" OR Processes.parent_process_name =  "wmic.exe" Processes.process_name = "vssadmin.exe" Processes.process="*resize*" Processes.process="*shadowstorage*" Processes.process="*/maxsize*" by Processes.parent_process_name Processes.parent_process Processes.process_name Processes.process Processes.dest Processes.user Processes.process_id Processes.process_guid 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5|`security_content_ctime(lastTime)` 
6| `resize_shadowstorage_volume_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	N/A	'crowdstrike:events:sensor'	'crowdstrike'
Sysmon EventID 1	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688	Windows	'xmlwineventlog'	'XmlWinEventLog:Security'

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

network admin can resize the shadowstorage for valid purposes.

Associated Analytic Story

• BlackByte Ransomware

• Clop Ransomware

Risk Based Analytics (RBA)

References

• https://www.mandiant.com/resources/fin11-email-campaigns-precursor-for-ransomware-data-theft

• https://blog.virustotal.com/2020/11/keep-your-friends-close-keep-ransomware.html

• https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1490/T1490.md

• https://redcanary.com/blog/blackbyte-ransomware/

• https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/vssadmin-resize-shadowstorage

Detection Testing

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: GitHub | Version: 3