---
type: "term"
title: "Patient Zero"
description: "In TLCTC context: the first system compromised in an attack, representing the initial entry point before lateral movement occurs."
resource: "tlctc:term:patient-zero"
tags:
  - "glossary"
---
# Patient Zero

In TLCTC context: the first system compromised in an attack, representing the initial entry point before lateral movement occurs. Patient Zero systems are critical because they are typically exposed systems that cannot be fully protected by Umbrella Controls alone and require robust Local Controls. After Patient Zero compromise, attacks follow the lateral movement paradigm through the internal network.

**Reference:** V1.9.1 §A (Umbrella Controls)

See also: Local Controls, Umbrella Controls, Lateral Movement