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Description

This analytic is developed to detect suspicious registry modifications targeting BitLocker settings. The malware ShrinkLocker alters various registry keys to 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.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2024-06-19
  • Author: Teoderick Contreras, Splunk
  • ID: bd1c770f-1b55-411e-b49e-20d07bcac5f8

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1112 Modify Registry Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Registry where (Registry.registry_path= "*\\Policies\\Microsoft\\FVE\\*" Registry.registry_value_name IN("EnableBDEWithNoTPM", "EnableNonTPM", "UseAdvancedStartup") Registry.registry_value_data = 0x00000001) OR (Registry.registry_path= "*\\Policies\\Microsoft\\FVE\\*" Registry.registry_value_name IN("UsePIN", "UsePartialEncryptionKey", "UseTPM", "UseTPMKey", "UseTPMKeyPIN", "UseTPMPIN") Registry.registry_value_data = 0x00000002) by Registry.registry_key_name Registry.user Registry.registry_path Registry.registry_value_data Registry.action Registry.dest Registry.registry_value_name 
| `drop_dm_object_name(Registry)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_modify_registry_configure_bitlocker_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_modify_registry_configure_bitlocker_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
  • Registry.registry_path
  • Registry.registry_key_name
  • Registry.registry_value_name
  • Registry.registry_key_name
  • Registry.user
  • Registry.dest
  • Registry.action
  • Registry.registry_value_data
  • Registry.process_guid

How To Implement

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

RBA

Risk Score Impact Confidence Message
64.0 80 80 A registry modification in Windows bitlocker registry settings on $dest$

: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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