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Author: nterl0k

windows_bitLocker_suspicious_command_usage.yml

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+name: Windows BitLocker Suspicious Command Usage
+id: d0e6ec70-6e40-41a2-8b93-8d9ff077a746
+version: 1
+date: '2025-02-10'
+author: Steven Dick
+status: production
+type: TTP
+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.
+data_source: 
+- Sysmon EventID 1
+- Windows Event Log Security 4688
+- CrowdStrike ProcessRollup2
+search: |-
+  | tstats `security_content_summariesonly` values(Processes.process) as process, values(Processes.parent_process) as parent_process min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name = manage-bde.exe AND Processes.process IN ("* -protectors -disable *","* -protectors -delete *","* –forcerecovery *","* -lock *") by Processes.dest Processes.user Processes.process_name Processes.parent_process_name
+  | `drop_dm_object_name(Processes)` 
+  | `security_content_ctime(firstTime)` 
+  | `security_content_ctime(lastTime)`
+  | `windows_bitlocker_suspicious_command_usage_filter`
+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.
+references:
+- https://attack.mitre.org/techniques/T1486/
+- https://www.nccgroup.com/us/research-blog/nameless-and-shameless-ransomware-encryption-via-bitlocker/
+- https://www.bitdefender.com/en-us/blog/businessinsights/shrinklocker-decryptor-from-friend-to-foe-and-back-again
+- https://www.bleepingcomputer.com/news/security/new-shrinklocker-ransomware-uses-bitlocker-to-encrypt-your-files/
+drilldown_searches:
+- name: View the detection results for - "$dest$" and "$user$"
+  search: '%original_detection_search% | search dest = "$dest$" user = "$user$"'
+  earliest_offset: $info_min_time$
+  latest_offset: $info_max_time$
+- name: View risk events for the last 7 days for - "$dest$" and "$user$"
+  search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$","$user$") starthoursago=168  | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
+  earliest_offset: $info_min_time$
+  latest_offset: $info_max_time$
+- name: Investigate processes on $dest$ 
+  search: '| from datamodel Endpoint.Processes
+| search process_name = $process_name$ AND dest = "$dest$"'
+  earliest_offset: $info_min_time$
+  latest_offset: $info_max_time$
+rba:
+  message: A suspicious Windows BitLocker command was run by $user$ detected on $dest$
+  risk_objects: 
+  - field: dest
+    type: system
+    score: 60
+  - field: user
+    type: user
+    score: 60
+  threat_objects: 
+  - field: parent_process
+    type: process
+tags:
+  analytic_story: 
+  - ShrinkLocker
+  asset_type: Endpoint
+  mitre_attack_id: 
+  - T1486
+  - T1490
+  product: 
+  - Splunk Enterprise
+  - Splunk Enterprise Security
+  - Splunk Cloud
+  security_domain: endpoint
+tests:
+- name: True Positive Test
+  attack_data:
+  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1486/bitlocker_sus_commands/bitlocker_sus_commands.log
+    source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
+    sourcetype: XmlWinEventLog