name: Windows DiskCryptor Usage
id: d56fe0c8-4650-11ec-a8fa-acde48001122
version: 1
date: '2021-11-15'
author: Michael Haag, Splunk
type: Hunting
datamodel:
- Endpoint
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.
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
  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 Processes.process Processes.process_id
  Processes.parent_process_id | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)`
  | `security_content_ctime(lastTime)` | `windows_diskcryptor_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: 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.
references:
- https://thedfirreport.com/2021/11/15/exchange-exploit-leads-to-domain-wide-ransomware/
- https://github.com/DavidXanatos/DiskCryptor
tags:
  analytic_story:
  - Ransomware
  confidence: 50
  context:
  - Source:Endpoint
  - Stage:Defense Evasion
  dataset:
  - https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1486/dcrypt/windows-sysmon.log
  impact: 70
  kill_chain_phases:
  - Exploitation
  message: An instance of $parent_process_name$ spawning $process_name$ was identified
    on endpoint $dest$ by user $user$ attempting to encrypt disks.
  mitre_attack_id:
  - T1486
  observable:
  - name: user
    type: User
    role:
    - Victim
  - name: dest
    type: Hostname
    role:
    - Victim
  - name: parent_process_name
    type: Process
    role:
    - Parent Process
  - name: process_name
    type: Process
    role:
    - Child Process
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - _time
  - Processes.dest
  - Processes.user
  - Processes.parent_process_name
  - Processes.parent_process
  - Processes.original_file_name
  - Processes.process_name
  - Processes.process
  - Processes.process_id
  - Processes.parent_process_path
  - Processes.process_path
  - Processes.parent_process_id
  risk_score: 35
  security_domain: endpoint
  asset_type: Endpoint