name: Windows MSHTA Inline HTA Execution
id: 24962154-9524-11ec-9333-acde48001122
version: 1
date: '2022-02-23'
author: Michael Haag, Splunk
type: TTP
datamodel:
- Endpoint_Processes
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: '| from read_ssa_enriched_events() | eval timestamp=parse_long(ucast(map_get(input_event,
  "_time"), "string", null)), cmd_line=lower(ucast(map_get(input_event, "process"),
  "string", null)), process_name=lower(ucast(map_get(input_event, "process_name"),
  "string", null)), process_path=ucast(map_get(input_event, "process_path"), "string",
  null), parent_process_name=ucast(map_get(input_event, "parent_process_name"), "string",
  null), event_id=ucast(map_get(input_event, "event_id"), "string", null) | where
  cmd_line IS NOT NULL AND process_name IS NOT NULL | where process_name="mshta.exe"
  AND (like (cmd_line, "%vbscript%") OR like (cmd_line, "%javascript%") OR like (cmd_line,
  "%about%")) | eval start_time=timestamp, end_time=timestamp, entities=mvappend(ucast(map_get(input_event,
  "dest_user_id"), "string", null), ucast(map_get(input_event, "dest_device_id"),
  "string", null)), body=create_map(["event_id", event_id, "cmd_line", cmd_line, "process_name",
  process_name, "parent_process_name", parent_process_name, "process_path", process_path])
  | into write_ssa_detected_events();'
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: 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
  - Living Off The Land
  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-security.log
  impact: 80
  kill_chain_phases:
  - Exploitation
  message: An instance of $parent_process_name$ spawning $process_name$ was identified
    on endpoint $dest_device_id$ by user $dest_user_id$ executing with inline HTA,
    indicative of defense evasion.
  mitre_attack_id:
  - T1218.005
  - T1218
  nist:
  - PR.PT
  - DE.CM
  observable:
  - name: dest_user_id
    type: User
    role:
    - Victim
  - name: dest_device_id
    type: Hostname
    role:
    - Victim
  - name: parent_process_name
    type: Process
    role:
    - Parent Process
  - name: process_name
    type: Process
    role:
    - Child Process
  product:
  - Splunk Behavioral Analytics
  required_fields:
  - _time
  - dest_device_id
  - process_name
  - parent_process_name
  - process_path
  - dest_user_id
  - process
  - cmd_line
  risk_score: 80
  security_domain: endpoint
  asset_type: Endpoint