What Is a Zero Trust Architecture? A Complete Guide

If your organization isn’t implementing Zero Trust, it’s not building cyber resilience.

Cybersecurity threats are ever evolving, and traditional defense mechanisms are no longer sufficient. With breaches and ransomware attacks unavoidable, it’s key for organizations to adopt Zero Trust.

In this comprehensive guide, we will detail what it means to build a Zero Trust architecture, exploring its core concept, network design principles, and its pivotal role in securing data. Additionally, we will delve into the crucial aspect of Zero Trust Segmentation, a foundational piece of any Zero Trust architecture.

What is a Zero Trust security strategy?

At its core, the Zero Trust security model is a paradigm shift from the traditional trust model of security.

In an era marked by remote work, cloud-based services, and increasingly complex, hyper-connected networks, the perimeter-centric model is no longer effective. The perimeter no longer exists — it’s distributed across environments, users, and devices around the globe.  

Traditional prevention and detection technologies, while important elements of any security stack, were built when networks had clear, static perimeters. Today, they’re not enough to stop the spread of inevitable breaches and ransomware attacks.  

Zero Trust recognizes that threats can come from both external and internal sources, necessitating a proactive and adaptive security approach. The model insists that organizations should not automatically trust any application or workload, regardless of their location. Instead, they should assume breaches will happen and prepare for them with breach containment technologies.  

The Zero Trust model was created by John Kindervag during the 2010s and focused on:

• Providing consistent segmentation across locations and hosts, including public and private clouds alongside on-premises environments
• Assuming risk is inherent both outside and inside the network
• Challenging the decades-long trust model of security which assumed anything inside the network was inherently allowed

It’s important to note that Zero Trust isn’t a technology, product, or platform — it’s an architectural model that can be implemented at any organization of any size, location, or industry.

What is a Zero Trust architecture?

Unlike traditional security models that assume implicit trust within the network perimeter and skepticism outside it, Zero Trust assumes zero inherent trust — both internally and externally. Every workload, application, user, device, or system attempting to access resources is rigorously authenticated, authorized, and continuously monitored.

If one thing is true across all breaches and ransomware, it’s that they like to move laterally. The core focus of a Zero Trust architecture is to address the risk of lateral movement and data exfiltration by breaches and ransomware attacks.  

Zero Trust doesn’t assume that movement or exfiltration can be entirely prevented. Instead, it puts proactive measures in place to stop and slow down attacks when they happen.

4 core Zero Trust architecture design principles

Implementing Zero Trust architecture involves adhering to specific principles and best practices in network design. Let's explore the five key elements that constitute a robust Zero Trust network:  

1. Least-privilege access

The principle of least privilege ensures that users and systems have the minimum level of access required to perform their tasks. This limits the attack surface, reducing the potential impact of security incidents. By granting only necessary permissions, organizations minimize the risk of unauthorized access and data breaches.

2. Continuous authentication

‍Traditional security models often authenticate workloads, applications, and users only at the point of entry. Zero Trust advocates for continuous authentication both outside and inside the network. This dynamic approach involves assessing the workload’s, application’s, or user’s identity and access rights continuously, adjusting them based on real-time changes in behavior, device status, and other contextual factors.

3. Endpoint trustworthiness

‍Zero Trust extends its scrutiny beyond user authentication to include the trustworthiness of endpoint devices. Organizations should evaluate the security posture of devices, considering factors such as patch levels, security configurations, and compliance with organizational policies. Only devices that meet predefined security standards are granted access.

4. Zero Trust Segmentation (ZTS)

‍ZTS, also called microsegmentation, is a foundational element of any Zero Trust architecture. Instead of relying on a monolithic perimeter to defend the entire network, organizations use ZTS to create small, isolated segments within the network. Each segment has its own security controls, restricting lateral movement and containing potential breaches. This granular approach enhances overall cyber resilience and helps achieve many global security compliance mandates.

Zero Trust Segmentation: A foundational component of Zero Trust  

ZTS is a cornerstone of any Zero Trust architecture, providing an effective means to compartmentalize and control network traffic. This approach involves dividing the network into smaller, isolated segments, each with its own set of security controls. Compared to static, legacy firewalls, ZTS makes it simpler to segment the network.  

ZTS solves some of the most pressing security challenges:

• ‍Stop lateral movement: One of the primary objectives of ZTS is to stop breaches and ransomware attacks from spreading within a network, something that’s also called lateral movement. In traditional security models, once a threat gains access to the network, it can move freely, potentially compromising sensitive data, accessing critical assets, and halting operations. ZTS restricts this lateral movement, preventing threats from spreading across the network. ‍
• Isolate and secure critical assets: By segmenting the network based on business functions, data sensitivity, and user roles, organizations can prioritize the protection of critical assets. High-value data and systems can be isolated within specific segments with enhanced security controls, reducing the risk of unauthorized access. ‍
• Get end-to-end visibility across the hybrid attack surface: ZTS acknowledges that granular segmentation cannot happen without complete, end-to-end visibility of all workload and application traffic and communication across the entire network, including the cloud, endpoints, and data centers. Organizations use this visibility to gain insight into security risks to make better-informed decisions about where segmentation needs to take place.
• ‍Facilitate compliance: ZTS meets many global regulatory compliance requirements. By providing end-to-end visibility, clearly defining security policy, and encrypting in-transit between workloads, ZTS helps organizations demonstrate adherence to industry-specific regulations and standards.
• Granular, dynamic response to threats: ZTS enhances an organization's ability to take an agile response to emerging threats. In the event of a security incident or suspicious activity, organizations can quickly isolate affected segments, minimizing the potential impact on the overall network.

8 steps to implementing a Zero Trust architecture

Adopting a Zero Trust architecture requires a strategic and phased approach. Here are key steps organizations should take to implement Zero Trust successfully and how Illumio ZTS can help:

1. Identify your data

To get started on your Zero Trust journey, it’s important to know what you need to protect. Get visibility into where and what your sensitive data is by taking an inventory.

2. Discover traffic

‍You can’t secure what you can’t see. Illumio ZTS' application dependency map can help you get complete, real-time visibility into traffic flows between applications and application dependencies so that you can better understand your organization’s attack surface. Make sure that your visibility reflects network changes, especially the fast-paced changes in the cloud, so that you have an accurate picture of the network in real time.

3. Define security policy

‍Seeing network traffic flows will help you start building a Zero Trust architecture with default-deny security rules. Illumio ZTS can help you automatically generate the optimal policy for each application and identify high-risk or unnecessary traffic flows.  

4. Encrypt in-transit data

‍An important part of any Zero Trust architecture — in addition to many compliance requirements — is encrypting in-transit data across all environments. Illumio ZTS enables in-transit data encryption at the individual workload with Illumio SecureConnect which uses the IPSec encryption libraries present in all modern operating systems.

5. Test

‍Testing your new Zero Trust security policies is a vital part of the workflow, giving you a way to model how policies will impact the network without going into full enforcement. With Illumio’s simulation mode, security teams can ensure policy implementation has less risk, fewer misconfigurations, and doesn’t result in network outages or availability problems.  ‍

6. Enforce

‍After testing the policies in simulation mode, it’s time for full enforcement. Track alerts for policy violations in real-time. Use Illumio to get alerts combined with meaningful, contextual data and have full visibility throughout the application lifecycle.

7. Monitor and maintain

‍Keeping and maintaining your enterprise security and your implementation requires constant work and effort. Remember that Zero Trust architecture is not a technology, but a framework and process. With what you learned you can implement Zero Trust Segmentation with each new application in your enterprise and find the optimal workflow over time while maintaining a never trust, always verify approach.

8. Embrace automation and orchestration

Managing today’s complex, ever-changing networks require security teams to embrace automation and orchestration. With these modern tools, teams can better maintain a stable, predictable, and reliable network.  

Get insight into how Illumio customers are building a Zero Trust architecture. Read our customer success stories.

Proactive, modern cybersecurity starts with a Zero Trust architecture

As organizations navigate increasing complexity and security threats, embracing Zero Trust is not just a strategic choice but a necessity to stay ahead. A Zero Trust architecture helps organizations take a proactive cybersecurity stance, empowering them to protect their data and infrastructure in an increasingly interconnected and dynamic world.

Learn more about Illumio ZTS today. Contact us for a free consultation and demo.