ClosedClsid is a sandbox setting in Sandboxie Ini available since v0.5.3a / 5.45.2. It specifies the COM class identifiers for unsandboxed COM objects that should not be accessible by a sandboxed program.
Usage:
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[DefaultBox]
ClosedClsid={8BC3F05E-D86B-11D0-A075-00C04FB68820}
This example makes the Windows Management and Instrumentation not accessible to sandboxed programs.
Related Sandboxie Plus setting: Sandbox Options > Resource Access > COM > Add COM Object > Access column > Closed