What is this security model called?

Zero Trust rejects the old assumption that anything already inside a company's firewall must be safe. Instead, it treats every user, device, and connection as potentially hostile, requiring continuous identity checks and strict, minimal access permissions no matter where the request originates. This approach limits how far an attacker can roam even after breaching one system, since gaining a foothold no longer grants automatic trust across the whole network.

'Open Trust' is not a real cybersecurity model and simply describes the opposite, riskier approach Zero Trust was designed to replace. 'Perimeter Defense' is the older strategy of guarding only the network's outer edge, which Zero Trust specifically moves away from because it fails once an intruder gets past that single boundary.

Zero Trust became especially important as remote work spread, since employees now log in from home networks, coffee shops, and personal devices scattered far outside any traditional office perimeter.