Detection: Windows BitLocker Suspicious Command Usage

Updated Date: 2025-02-10 ID: d0e6ec70-6e40-41a2-8b93-8d9ff077a746 Author: Steven Dick Type: TTP Product: Splunk Enterprise Security

Description

This analytic is developed to detect the usage of BitLocker commands used to disable or impact boot settings. The malware ShrinkLocker uses various commands change how BitLocker handles encryption, potentially bypassing TPM requirements, enabling BitLocker without TPM, and enforcing specific startup key and PIN configurations. Such modifications can weaken system security, making it easier for unauthorized access and data breaches. Detecting these changes is crucial for maintaining robust encryption and data protection.

Search

 1
 2| tstats `security_content_summariesonly` min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes 
 3where Processes.process_name = manage-bde.exe AND Processes.process IN ("* -protectors -disable *","* -protectors -delete *","* -forcerecovery *","* -lock *") 
 4by Processes.action Processes.dest Processes.original_file_name Processes.parent_process Processes.parent_process_exec 
 5Processes.parent_process_guid Processes.parent_process_id Processes.parent_process_name 
 6Processes.parent_process_path Processes.process Processes.process_exec Processes.process_guid Processes.process_hash 
 7Processes.process_id Processes.process_integrity_level Processes.process_name Processes.process_path 
 8Processes.user Processes.user_id Processes.vendor_product 
 9
10| `drop_dm_object_name(Processes)` 
11
12| `security_content_ctime(firstTime)` 
13
14| `security_content_ctime(lastTime)`
15
16| `windows_bitlocker_suspicious_command_usage_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

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
windows_bitlocker_suspicious_command_usage_filter	`search *`

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

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1486	Data Encrypted for Impact	Impact
T1490	Inhibit System Recovery	Impact

Actions on Objectives

DE.CM

CIS 10

Default Configuration

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

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Notable	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Risk Event	True

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the Endpoint datamodel in the Processes node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.

Known False Positives

Administrators may enable or disable this feature that may cause some false positive.

Associated Analytic Story

ShrinkLocker

Risk Based Analytics (RBA)

Risk Message:

A suspicious Windows BitLocker command was run by $user$ detected on $dest$

Risk Object	Risk Object Type	Risk Score	Threat Objects
dest	system	60	parent_process
user	user	60	parent_process

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`

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: 2