Asynchronous Procedure Calls
Use APC to inject dll
code from:http://blogs.microsoft.co.il/pavely/2017/03/14/injecting-a-dll-without-a-remote-thread/
More details;
Use NtCreateThreadEx to inject dll
Use NtCreateThreadEx + LdrLoadDll to inject dll
Use CreateRemoteThread to inject dll,usually used under WinXP