Disable Adobe Flash Player in Office (CLSID 6E, 16.0)
The DWORD value `1024`, equivalent to `0x00000400`, sets the Office COM kill bit for the COM object identified by CLSID `{D27CDB6E-AE6D-11CF-96B8-444553540000}`.
since 0.9.8.11
Purpose
Show registry keys (1)
HKLM\software\microsoft\Office\16.0\Common\COM Compatibility\{D27CDB6E-AE6D-11CF-96B8-444553540000}\Compatibility Flags
The DWORD value 1024, equivalent to 0x00000400, sets the Office COM kill bit for the COM object identified by CLSID {D27CDB6E-AE6D-11CF-96B8-444553540000}. This CLSID identifies the Adobe Flash Player ActiveX control named “Shockwave Flash Object.”
The kill bit prevents affected Office applications from activating this COM object. It applies to applications such as Word, Excel, PowerPoint, Publisher, and Visio that honor the Office COM kill-bit list.
In Office 2016 with security update KB3178703 or a superseding update, the block generally covers all in-process activation by Office. In addition to embedded or linked objects in documents, this prevents the control from being loaded into an Office process through mechanisms such as add-ins.
Notes
Security
Blocking the control reduces the attack surface available to malicious or specially crafted Office content that attempts to exploit vulnerabilities in the Flash ActiveX control. The protection is limited to the specified COM class in affected Office processes. It does not remove Flash, block different Flash CLSIDs, or prevent other applications from activating Flash components.
The Office COM kill-bit list is separate from the former Internet Explorer ActiveX kill-bit list. This value therefore does not disable Flash system-wide.
Possible side effects
Office documents, templates, or add-ins that depend on the “Shockwave Flash Object” under this CLSID can no longer load or run that content. Depending on the Office application, the content may be absent or appear as an unavailable or non-insertable object.
Notes
The specified path is the documented Office 2016 location for 64-bit Office on 64-bit Windows and for 32-bit Office on 32-bit Windows. For 32-bit Office on 64-bit Windows, Microsoft documents the corresponding location under HKLM\Software\Wow6432Node\Microsoft\Office\16.0\Common\COM Compatibility. The value has an effect only when the installed Office architecture reads the specified registry view.
If an ActivationFilterOverride DWORD with a value of 1 is also present for this CLSID, the block is limited to COM objects embedded in or linked from Office documents. Without that exception, an appropriately updated Office installation applies the broader in-process block.
Adobe Flash Player has been unsupported since December 31, 2020, and Microsoft removed the Windows-supplied component through Windows updates. This registry value can still be relevant if the ActiveX control remains installed from another source.
Microsoft documentation
Microsoft Support: Security Settings for COM objects in Office
Microsoft Learn: Microsoft Security Advisory 2755801
Microsoft Support: KB4577586—Update for the removal of Adobe Flash Player