Let’s discuss a type of attack methodology, Attack in Depth, as recently demonstrated by a well-resourced attacker. The technique is neigh non-existent in the I.T. infrastructure space, but is expected to become standard for future attacks against critical infrastructure (by nation state / APT attackers.) The purpose of this white paper is to define this style of attack. The recognition, identification, and naming of a thing will make discussions of the technique and ultimately development of prevention measures easier.