> Is it a backdoor if the owner put it there deliberately to be able to detect regular OS-level viruses? Yes. Unless the owner has a perfect guarantee that th

> Is it a backdoor if the owner put it there deliberately to be able to detect regular OS-level viruses? Yes. Unless the owner has a perfect guarantee that they will be the only ones who can use it and the will be aware of it every time it is used. The likelihood of this being true in the given environment is next to zero. They own it, though. They're free to fool themselves about it if they like.