ssa___windows_rundll32_inline_hta_execution.yml

name: Windows Rundll32 Inline HTA Execution
id: 0caa1dd6-94f5-11ec-9786-acde48001122
version: 4
date: '2022-02-23'
author: Michael Haag, Splunk
status: production
type: TTP
description: The following analytic identifies "rundll32.exe" execution with inline
  protocol handlers. "JavaScript", "VBScript", and "About" are the only supported
  options when invoking HTA content directly on the command-line. This type of behavior
  is commonly observed with fileless malware or application whitelisting bypass techniques.
  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
  "rundll32.exe" and its parent process.
data_source:
- Windows Security 4688
search:
  selection1:
    process.cmd_line|contains:
    - about
    - javascript
    - vbscript
    process.file.name: rundll32.exe
  condition: selection1
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
  - NOBELIUM Group
  - Living Off The Land
  asset_type: Endpoint
  confidence: 80
  impact: 70
  message: Suspicious $process_name$ inline HTA execution on $dest_device_id$.
  mitre_attack_id:
  - T1218
  - T1218.005
  observable: []
  product:
  - Splunk Behavioral Analytics
  required_fields: []
  kill_chain_phases:
  - Exploitation
  risk_score: 56
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1218.005/atomic_red_team/windows-security.log
    source: WinEventLog:Security