The main red flags that help in detecting injected code inside a process is that the allocated memory that contains the shellcode or the loaded DLL is always allocated with EXECUTE permission and doesn't represent a mapped file. When a module (an executable file) gets loaded using Windows PE Loader, it gets loaded with an IMAGE flag to represent that it's a memory map of an executable file. But when this memory page is allocated normally using VirtualAlloc, it gets allocated with a PRIVATE flag to show that it is allocated for data:
It's not common to see private allocated memory having the EXECUTE permission, and it's also not common (which most shellcode injections do) to have the WRITE permission with the EXECUTE permission (READ_WRITE_EXECUTE).
In Volatility, there is a command called malfind....
