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Added detection testing service results inWindows DiskCryptor Usage
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@@ -6,22 +6,33 @@ author: Michael Haag, Splunk
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type: Hunting
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datamodel:
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- Endpoint
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description: 'The following analytic identifies DiskCryptor process name of dcrypt.exe or internal name dcinst.exe. This utility has been utilized by adversaries to encrypt disks manually during an operation. In addition, during install, a dcrypt.sys driver is installed and requires a reboot in order to take effect. There are no command-line arguments used.'
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description: The following analytic identifies DiskCryptor process name of dcrypt.exe
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or internal name dcinst.exe. This utility has been utilized by adversaries to encrypt
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disks manually during an operation. In addition, during install, a dcrypt.sys driver
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is installed and requires a reboot in order to take effect. There are no command-line
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arguments used.
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search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
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as lastTime from datamodel=Endpoint.Processes where (Processes.process_name="dcrypt.exe" OR Processes.original_file_name=dcinst.exe) by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.original_file_name
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Processes.process Processes.process_id Processes.parent_process_id
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| `drop_dm_object_name(Processes)`
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| `security_content_ctime(firstTime)`
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| `security_content_ctime(lastTime)` | `windows_diskcryptor_usage_filter`'
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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.
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known_false_positives: It is possible false positives may be present based on the internal name dcinst.exe, filter as needed. It may be worthy to alert on the service name.
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as lastTime from datamodel=Endpoint.Processes where (Processes.process_name="dcrypt.exe"
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OR Processes.original_file_name=dcinst.exe) by Processes.dest Processes.user Processes.parent_process_name
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Processes.process_name Processes.original_file_name Processes.process Processes.process_id
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Processes.parent_process_id | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)`
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| `security_content_ctime(lastTime)` | `windows_diskcryptor_usage_filter`'
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how_to_implement: To successfully implement this search you need to be ingesting information
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on process that include the name of the process responsible for the changes from
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your endpoints into the `Endpoint` datamodel in the `Processes` node. In addition,
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confirm the latest CIM App 4.20 or higher is installed and the latest TA for the
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endpoint product.
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known_false_positives: It is possible false positives may be present based on the
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internal name dcinst.exe, filter as needed. It may be worthy to alert on the service
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name.
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references:
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- https://thedfirreport.com/2021/11/15/exchange-exploit-leads-to-domain-wide-ransomware/
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- https://github.com/DavidXanatos/DiskCryptor
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- https://thedfirreport.com/2021/11/15/exchange-exploit-leads-to-domain-wide-ransomware/
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- https://github.com/DavidXanatos/DiskCryptor
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tags:
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analytic_story:
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- Ransomware
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dataset: []
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dataset:
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- https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1486/dcrypt/windows-sysmon.log
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kill_chain_phases:
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- Exploitation
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mitre_attack_id:
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@@ -34,11 +45,11 @@ tags:
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- _time
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- Processes.dest
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- Processes.user
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- Processes.parent_process_name #parent process name
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- Processes.parent_process #parent cmdline
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- Processes.parent_process_name
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- Processes.parent_process
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- Processes.original_file_name
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- Processes.process_name #process name
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- Processes.process #process cmdline
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- Processes.process_name
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- Processes.process
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- Processes.process_id
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- Processes.parent_process_path
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- Processes.process_path
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@@ -46,12 +57,12 @@ tags:
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security_domain: endpoint
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impact: 70
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confidence: 50
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# (impact * confidence)/100
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risk_score: 35
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context:
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- Source:Endpoint
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- Stage:Defense Evasion
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message: An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ attempting to encrypt disks.
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message: An instance of $parent_process_name$ spawning $process_name$ was identified
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on endpoint $dest$ by user $user$ attempting to encrypt disks.
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observable:
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- name: user
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type: User
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@@ -69,4 +80,4 @@ tags:
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type: Process
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role:
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- Child Process
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automated_detection_testing: passed
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