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splunk-security_content/dev/endpoint/detect_html_help_renamed.yml
2023-01-20 13:24:15 +01:00

78 lines
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YAML

name: Detect HTML Help Renamed
id: 62fed254-513b-460e-953d-79771493a9f3
version: 4
date: '2022-04-07'
author: Michael Haag, Splunk
status: production
type: Hunting
description: The following analytic identifies a renamed instance of hh.exe (HTML
Help) executing a Compiled HTML Help (CHM). This particular technique will load
Windows script code from a compiled help file. CHM files may contain nearly any
file type embedded, but only execute html/htm. Upon a successful execution, the
following script engines may be used for execution - JScript, VBScript, VBScript.Encode,
JScript.Encode, JScript.Compact. Analyst may identify vbscript.dll or jscript.dll
loading into hh.exe upon execution. The "htm" and "html" file extensions were the
only extensions observed to be supported for the execution of Shortcut commands
or WSH script code. During investigation, identify script content origination. Validate
it is the legitimate version of hh.exe by reviewing the PE metadata. hh.exe is natively
found in C:\Windows\system32 and C:\Windows\syswow64.
data_source:
- Sysmon Event ID 1
search:
selection1:
OriginalFileName: HH.EXE
Image|endswith: hh.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 a renamed instance of hh.exe will be used
legitimately, filter as needed.
references:
- https://attack.mitre.org/techniques/T1218/001/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.001/T1218.001.md
- https://lolbas-project.github.io/lolbas/Binaries/Hh/
tags:
analytic_story:
- Suspicious Compiled HTML Activity
- Living Off The Land
asset_type: Endpoint
confidence: 100
impact: 80
message: The following $process_name$ has been identified as renamed, spawning from
$parent_process_name$.
mitre_attack_id:
- T1218
- T1218.001
observable:
- name: user
type: User
role:
- Victim
- name: Computer
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
risk_score: 80
security_domain: endpoint
tests:
- name: True Positive Test
attack_data:
- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1218.001/atomic_red_team/windows-sysmon.log
source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
sourcetype: xmlwineventlog