name: Detect mshta inline hta execution
id: a0873b32-5b68-11eb-ae93-0242ac130002
version: 5
date: '2021-01-20'
author: Bhavin Patel, Michael Haag, Splunk
type: batch
datamodel:
- Endpoint
description: The following analytic identifies "mshta.exe" execution with inline protocol
  handlers. "JavaScript", "VBScript", and "About" are the only supported options when
  invoking HTA content directly on the command-line. The search will return the first
  time and last time these command-line arguments were used for these executions,
  as well as the target system, the user, process "mshta.exe" and its parent process.
search: '| tstats `security_content_summariesonly` count 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=mshta.exe
  (Processes.process=*vbscript* OR Processes.process=*javascript* OR Processes.process=*about*)
  by Processes.user Processes.process_name Processes.parent_process_name Processes.dest  |
  `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)`| `security_content_ctime(lastTime)`
  | `detect_mshta_inline_hta_execution_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.
known_false_positives: Although unlikely, some legitimate applications may exhibit
  this behavior, triggering a false positive.
references:
- https://github.com/redcanaryco/AtomicTestHarnesses
- https://redcanary.com/blog/introducing-atomictestharnesses/
- https://docs.microsoft.com/en-us/windows/win32/search/-search-3x-wds-extidx-prot-implementing
tags:
  analytic_story:
  - Suspicious MSHTA Activity
  asset_type: Endpoint
  automated_detection_testing: passed
  cis20:
  - CIS 8
  confidence: 100
  context:
  - Source:Endpoint
  - Stage:Defense Evasion
  dataset:
  - https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1218.005/atomic_red_team/windows-sysmon.log
  impact: 90
  kill_chain_phases:
  - Exploitation
  message: An instance of $parent_process_name$ spawning $process_name$ was identified
    on endpoint $dest$ by user $user$ executing with inline HTA, indicative of defense
    evasion.
  mitre_attack_id:
  - T1218.005
  nist:
  - PR.PT
  - DE.CM
  observable:
  - name: user
    type: User
    role:
    - Victim
  - name: dest
    type: Hostname
    role:
    - Victim
  - name: parent_process_name
    type: Parent 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: 90
  security_domain: endpoint