Do you mean privilage escalation or have I misunderstood? i.e. you could for example exploit one of the recent Exchange vulnerabilities then use this to get SYSTEM and own the box.
Shellcode can be hard to write since it might be a small amount of code you can execute, you might not be able to jump precisely to your code, it might have to use a limited range of values (such as correctly parsing as something else) or other challenges.
> Windows x64 kernel-mode handcrafted shellcode to replace primary access token of executing process with SYSTEM process token for Elevation of Privilege(EoP).
So yes, privilege escalation.