The organizational condition in which entity infrastructure does not exist or has never reached the confidence threshold for a given perimeter. Undefended posture is visible and diagnosable: the organization knows it has no presence. Undefended posture on identity is rare; undefended posture on domain is common; undefended posture on vocabulary is nearly universal. Undefended posture is the least dangerous posture because the organization knows it needs to build. The tactical response to undefended posture is greenfield construction: build infrastructure from zero with no legacy constraints.