LoFP / 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.

Techniques

• T1204
• T1218

Sample rules

Process Activity via Compiled HTML File

• source: elastic
• technicques:
  • T1204
  • T1218

Description

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).

Detection logic

process where host.os.type == "windows" and event.type == "start" and
 process.parent.name : "hh.exe" and
 process.name : ("mshta.exe", "cmd.exe", "powershell.exe", "pwsh.exe", "powershell_ise.exe", "cscript.exe", "wscript.exe")