На самом деле есть, и даже COW.
https://groups.google.com/forum/#!topic/comp.os.ms-windows.programmer.nt.kernel-mode/hoN_RYtnp58
The most important parameter here is SectionHandle. If this parameter is NULL, the kernel will fork the current process. Otherwise, this parameter must be a handle of the SEC_IMAGE section object created on the EXE file before calling ZwCreateProcess().
NTSYSAPI NTSTATUS NTAPI ZwCreateProcess( OUT PHANDLE ProcessHandle, IN ACCESS_MASK DesiredAccess, IN POBJECT_ATTRIBUTES ObjectAttributes OPTIONAL, IN HANDLE ParentProcess, IN BOOLEAN InheritObjectTable, IN HANDLE SectionHandle OPTIONAL, IN HANDLE DebugPort OPTIONAL, IN HANDLE ExceptionPort OPTIONAL );
Ещё вот: forknt.c
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