Process Activity via Compiled HTML File

Elastic Stack Serverless Security

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: 9

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", "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: Signed 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/