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Allow only approved domains to use the TDC ActiveX control

The `120c` `REG_DWORD` value controls whether websites in the Internet zone may run the Tabular Data Control (TDC).

since 0.9.8.11

Purpose

Show registry keys (2)
  • HKLM\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3\120c
  • HKCU\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3\120c

The 120c REG_DWORD value controls whether websites in the Internet zone may run the Tabular Data Control (TDC). This legacy ActiveX control enables HTML pages to load, display, and filter data from delimited text files.

A value of 3 (URLPOLICY_DISALLOW) prevents websites in this zone from running the TDC ActiveX control. A value of 0 (URLPOLICY_ALLOW) permits it for all websites in the zone, provided that no other ActiveX or add-on policy blocks execution.

The policy title does not mean that this value maintains a separate allowlist of approved domains. According to Microsoft's documented behavior, 3 blocks the TDC control for every website in the Internet zone. The value itself contains no domain list.

The HKLM variant represents the computer policy, while the HKCU variant applies to the individual user. Both govern the same security-zone action.

Notes

Security

A value of 3 prevents Internet-zone content from instantiating this legacy, scriptable ActiveX control. This reduces the attack surface exposed to untrusted Internet content.

A value of 0 generally permits Internet-zone websites to use the TDC control. It does not enable every ActiveX control or override other security checks, add-on restrictions, or zone policies.

Possible side effects

Blocking the control can break legacy web applications that depend on TDC to load, display, sort, or filter data from text files. Modern websites are not normally affected.

Notes

Zone 3 is the Internet zone. This setting affects only components that use Internet Explorer security zones and ActiveX functionality. The modern Microsoft Edge engine does not support ActiveX; Microsoft Edge in IE mode does support ActiveX controls and honors Internet Explorer policies that affect security-zone settings.

Microsoft documentation

Microsoft Learn: InternetExplorer Policy CSP – InternetZoneAllowOnlyApprovedDomainsToUseTDCActiveXControl

Microsoft Learn: TDC Object

Microsoft Learn: What is Internet Explorer mode?

See also