.. /Mshtml.dll

Star

Paths:

• c:\windows\system32\mshtml.dll
• c:\windows\syswow64\mshtml.dll

Resources:

• https://twitter.com/pabraeken/status/998567549670477824
• https://windows10dll.nirsoft.net/mshtml_dll.html

Acknowledgements:

• Pierre-Alexandre Braeken (@pabraeken)

Detections:

• Sigma: https://github.com/SigmaHQ/sigma/blob/62d4fd26b05f4d81973e7c8e80d7c1a0c6a29d0e/rules/windows/process_creation/proc_creation_win_rundll32_susp_activity.yml

Execute

1. Invoke an HTML Application via mshta.exe (note: pops a security warning and a print dialogue box).

   rundll32.exe Mshtml.dll,PrintHTML "C:\temp\calc.hta"

   Use case

   Launch an HTA application.

   Privileges required

   User

   Operating systems

   Windows 10, Windows 11

   ATT&CK® technique

   T1218.011