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What is Zero Trust?

What is Zero Trust?

Since mobile users began connecting via unmanaged devices to business applications over the internet, there’s been growing need to implement zero trust security. When you can’t trust the connection, device, or network, zero trust sounds like a great idea. But in the last few years, there’s been a lot of confusion about what the term actually means.

Zero trust is a framework for enabling certain capabilities that secure organizations in the modern cloud and mobile world. A key principle of zero trust is least-privileged access, which assumes that no user or application should be inherently trusted. It begins on the basis that everything is hostile, and only establishes trust based upon the user identity and context—such as the user’s location, the security posture of the device, and the app or service being requested—with policy serving as the gatekeeper every step of the way.

How zero trust enables modernization

At its core, the concept is simple: zero trust = assume everything to be hostile. While this sounds obvious, the notion is antithetical to the corporate network security model. Since the early 1990s, companies have been building a network architecture with a secure perimeter using endpoint-based controls, relying on approved IP addresses, ports, and protocols to validate applications, data, and/or users, which are then trusted to communicate inside the network. 

In contrast, the zero trust approach treats all traffic, including traffic already inside the perimeter, as hostile. Unless workloads have been identified by a set of attributes—a workload fingerprint or identity—they are untrusted and blocked from communicating. Identity-based policies result in stronger security that travels with the workload wherever it communicates—in a public cloud, a hybrid environment, a container, or an on-premises network architecture. Because protection is environment-agnostic, applications and services are secured even if they communicate across network environments, requiring no architectural changes or policy updates. 

In the simplest terms, zero trust securely connects users, devices, and applications using business policies over any network.

Removing network location as a position of advantage eliminates excessive implicit trust, replacing it with explicit identity-based trust.
Gartner, Market Guide to Zero Trust Network Access, June 2020
Zero trust is being misused as a marketing term. Vendors are applying the term ‘Zero Trust’ to market everything in security, creating significant marketing confusion.
Gartner, 2019

The foundations of zero trust

Zero trust is not simply about a single technology like identity or remote access or network segmentation. Zero trust is a strategy, a foundation upon which to build a security ecosystem.  At its core are three tenets:

  1. Terminate every connection: Many technologies, such as firewalls, use a “passthrough” approach, which means that files are sent to their recipients at the same time they’re being inspected. If a malicious file is detected, an alert is sent, but it can often be too late. In contrast, zero trust terminates every connection so it can hold and inspect unknown files before they reach the endpoint. Built on a proxy architecture, zero trust operates inline and inspect all traffic at line speed, including encrypted traffic, executing deep data and threat analysis.
  2. Protect data using business policies based on context: Zero trust uses identity and device posture to verify access rights, and it applies business policies based upon context, including user, device, application being requested, and the type of content. As context changes, such as the user’s location or device, the access privileges are continually reassessed.
  3. Reduce risk by eliminating the attack surface: Zero trust connects users directly to the applications and resources they need, and never connects them to networks (see ZTNA). By enabling one-to-one connections (user-to-app and app-to-app), zero trust eliminates the risk of lateral movement and prevents a compromised device from infecting other network resources. With zero trust, users and applications are invisible to the internet, so they can’t be discovered or attacked.

Why adopt a zero trust security model?

Today’s networks are hostile places. They host business-critical applications and data, making them ripe for attack by cybercriminals who would like nothing more than to steal, destroy, or hold hostage sensitive data, such as personally identifiable information (PII), intellectual property (IP), and financial information for personal gain.
While no security is perfect, and data breaches will never be totally eliminated, zero trust reduces the attack surface and limits the blast radius—that is, the impact and severity—of a cyberattack, which reduces the time and cost of responding to and cleaning up after a data breach. 

Cybersecurity Insiders 2019 Zero Trust Adoption Report

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The Network Architect’s Guide to Adopting ZTNA

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Gartner Market Guide for Zero Trust Network Access

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Four benefits of zero trust

1. Reduces business and organizational risk

Zero trust assumes all applications and services are malicious and are disallowed from communicating until they can be positively verified by their identity attributes—immutable properties of the software or services themselves that meet predefined authentication and authorization requirements.

Zero trust, therefore, reduces risk because it uncovers what’s on the network and how those assets are communicating. Further, as baselines are created, a zero trust model reduces risk by eliminating overprovisioned software and services and continuously checking the “credentials” of every communicating asset.


2. Provides access control over cloud and container environments

Security practitioners’ greatest fears about moving to and using the cloud are loss of visibility and access control. Despite an evolution in cloud service provider (CSP) security, workload security remains a shared responsibility between the CSP and the organization using the cloud. That said, there is only so much an organization can affect inside someone else’s cloud.

With zero trust, security policies are based on the identity of communicating workloads and are tied directly to the workload itself. In this way, security stays as close as possible to the assets that require protection and is not affected by network constructs such as IP addresses, ports, and protocols. As a result, protection not only travels with the workload where it tries to communicate but remains unchanged even as the environment changes.


3. Helps reduce the risk of a data breach 

Because the zero trust model is focused on the workload, it’s easier for security teams to identify and stop malicious data-based activity. A zero trust approach always verifies, preventing workloads that are unverified from communicating anywhere on the system—to and from command-and-control, and between hosts, users, or applications and data (and any combination thereof). 

Any altered application or service, whether it’s a result of adversarial activity, misuse, or accident, is automatically untrusted until it can be verified again through a set of policies and controls. Even when verified and approved, communication is restricted to a “need-to-know” basis; in other words, secure access is locked down to only the users, hosts, or services that need it. 


4. Supports compliance initiatives

With zero trust, auditors (and others) achieve clearer insight into what data flows the organization has and can see how workloads are protected. Zero trust mitigates the number of places and ways network communications can be exploited, resulting in fewer negative audit findings and simpler remediation.

In addition, with zero trust segmentation (microsegmentation) implemented, organizations have the ability to create perimeters around certain types of sensitive data (e.g., PCI or credit card data, data backups) using fine-grained controls that keep regulated data separate from other, non-regulated data. When it comes time for an audit, or in the event of a data breach, a zero trust segmentation (microsegmentation) strategy provides superior visibility and control over flat network architectures that provide over-privileged access.

a diagram showing zero trust architecture

Getting started with zero trust

Designing for zero trust requires security and IT teams to focus on business concepts: What are we trying to protect? From whom? Recognize that a zero trust architecture underpins the entire security solution; technologies and processes are layered on top of the strategy, not the other way around.  

Zero trust can be delivered as a service, which is recommended by Gartner in its zero trust network access (ZTNA) framework. It can also be implemented in stages, with organizations starting with their most critical assets. As an alternative, they can start with non-critical assets as a test case before implementing zero trust more broadly. Regardless of your starting point, a zero trust solution returns immediate gains through risk reduction and security control.

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