Process Activity via Compiled HTML Fileedit

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: query

Rule indices:

  • winlogbeat-*

Severity: low

Risk score: 21

Runs every: 5 minutes

Searches indices from: now-6m (Date Math format, see also Additional look-back time)

Maximum signals per execution: 100


  • Elastic
  • Windows

Version: 2 (version history)

Added (Elastic Stack release): 7.6.0

Last modified (Elastic Stack release): 7.7.0

Potential false positivesedit

The HTML Help executable program (hh.exe) runs whenever a user clicks a compiled help (.chm) file or menu item that opens the help file inside the Help Viewer. This is not always malicious, but adversaries may abuse this technology to conceal malicious code.

Rule queryedit

event.code:1 and

Threat mappingedit


Rule version historyedit

Version 2 (7.7.0 release)
  • Formatting only.