Process Activity via Compiled HTML File

Compiled HTML files (.chm) are commonly distributed as part of the Microsoft HTML Help system. Adversaries may conceal malicious code in a CHM file and deliver it to a victim for execution. CHM content is loaded by the HTML Help executable program (hh.exe).

Rule type: eql

Rule indices:

• winlogbeat-*
• logs-endpoint.events.*
• logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[Date Math format], see also Additional look-back time)

Maximum alerts per execution: 100

References: None

Tags:

• Elastic
• Host
• Windows
• Threat Detection
• Execution

Version: 13

Rule authors:

• Elastic

Rule license: Elastic License v2

process where event.type in ("start", "process_started") and
 process.parent.name : "hh.exe" and
 process.name : ("mshta.exe", "cmd.exe", "powershell.exe", "pwsh.exe", "powershell_ise.exe", "cscript.exe", "wscript.exe")

Framework: MITRE ATT&CKTM

• Tactic:

  • Name: Execution
  • ID: TA0002
  • Reference URL: https://attack.mitre.org/tactics/TA0002/

• Technique:

  • Name: User Execution
  • ID: T1204
  • Reference URL: https://attack.mitre.org/techniques/T1204/

• Sub-technique:

  • Name: Malicious File
  • ID: T1204.002
  • Reference URL: https://attack.mitre.org/techniques/T1204/002/

• Tactic:

  • Name: Defense Evasion
  • ID: TA0005
  • Reference URL: https://attack.mitre.org/tactics/TA0005/

• Technique:

  • Name: System Binary Proxy Execution
  • ID: T1218
  • Reference URL: https://attack.mitre.org/techniques/T1218/

• Sub-technique:

  • Name: Compiled HTML File
  • ID: T1218.001
  • Reference URL: https://attack.mitre.org/techniques/T1218/001/