regsvr32.exe

Built-in Windows command-line utility that registers and unregisters DLL/ActiveX COM components. It can also load and execute remote COM scriptlets through scrobj.dll (Squiblydoo) and invoke local self-registering DLL exports; this can proxy code execution and may evade application-control policies that permit the binary and behavior. Scriptlet execution does not inherently register a COM object, bypass UAC, or alter the registry.