splunk-security_content/docs/_posts/2021-05-12-delete_shadowcopy_with_powershell.md

title, excerpt, categories, last_modified_at, toc, toc_label, tags

title	excerpt	categories	last_modified_at	toc	toc_label	tags
Delete ShadowCopy With PowerShell	Inhibit System Recovery	Endpoint	2021-05-12	true		Inhibit System Recovery Impact Splunk Enterprise Splunk Enterprise Security Splunk Cloud Endpoint

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Description

This following analytic detects PowerShell command to delete shadow copy using the WMIC PowerShell module. This technique was seen used by a recent adversary to deploy DarkSide Ransomware where it executed a child process of PowerShell to execute a hex encoded command to delete shadow copy. This hex encoded command was able to be decrypted by PowerShell log.

• Type: TTP
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2021-05-12
• Author: Teoderick Contreras, Splunk
• ID: 5ee2bcd0-b2ff-11eb-bb34-acde48001122

Annotations

ATT&CK

ID	Technique	Tactic
T1490	Inhibit System Recovery	Impact

Kill Chain Phase

• Exploitation

NIST

CIS20

CVE

Search

`powershell` EventCode=4104 Message= "*ShadowCopy*" (Message = "*Delete*" OR Message = "*Remove*") 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode Message ComputerName User 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `delete_shadowcopy_with_powershell_filter`

Macros

The SPL above uses the following Macros:

• powershell
• security_content_ctime

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

Required field

• _time
• EventCode
• Message
• ComputerName
• User

How To Implement

To successfully implement this search, you need to be ingesting logs with the powershell logs from your endpoints. make sure you enable needed registry to monitor this event.

Known False Positives

unknown

Associated Analytic story

• DarkSide Ransomware
• Ransomware
• Revil Ransomware

RBA

Risk Score	Impact	Confidence	Message
81.0	90	90	An attempt to delete ShadowCopy was performed using PowerShell on ComputerName by User.

ℹ️ 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://www.mandiant.com/resources/shining-a-light-on-darkside-ransomware-operations
• https://www.techtarget.com/searchwindowsserver/tutorial/Set-up-PowerShell-script-block-logging-for-added-security

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

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/revil/inf1/windows-powershell.log

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