What Is Zero Trust Network Access (ZTNA)? Ultimate 2025 Guide

Zero trust network access (ZTNA) is a security framework that enforces strict identity and device verification for every user and device attempting to access resources, regardless of their location or the network’s perceived safety. Unlike traditional security models that trust internal network users by default, ZTNA assumes no entity, whether internal or external, should be implicitly trusted. Access to applications and data is tightly controlled using continuous verification, reducing the likelihood of lateral movement following a breach.

ZTNA emerged as organizations recognized that perimeter-based security could not adequately protect against modern threats like compromised credentials, insider risk, and persistent threats. By shifting security from the network perimeter to the users, devices, and applications themselves, ZTNA addresses dynamic workforces, the prevalence of cloud services, and the expansion of remote work. The model enforces least-privilege access, meaning users get exactly the permissions they need—nothing more, nothing less.

In this article:

• How ZTNA Works
• ZTNA vs. VPN vs. SDP
• Key ZTNA Use Cases
• Types of ZTNA Solutions
• Best Practices for Successful ZTNA Adoption
• Implementing ZTNA in Browser Environments with Seraphic Security

How ZTNA Works

Zero trust network access (ZTNA) operates on the principle of “never trust, always verify.” It establishes secure, identity-aware connections between users and applications, without placing users directly on the network. Here’s how it works:

1. Authentication and Authorization Before Access

ZTNA starts with strong user and device authentication. Before a user can access any application, the system verifies their identity using methods like multi-factor authentication (MFA), single sign-on (SSO), or integration with identity providers (IdPs). This authentication process checks user credentials, authentication factors, and role-based attributes to validate identity.

Alongside user verification, ZTNA performs device posture assessments to evaluate the security status of the accessing device. This includes checking for operating system patches, antivirus status, disk encryption, and device management enrollment. Access decisions are made in real time based on both user and device trust levels.

2. Application-Level Segmentation

Unlike traditional network access models that expose broad segments of the internal network, ZTNA limits access to applications based on pre-defined policies. Users never get an IP-level view of the network. Instead, they connect only to the applications they’re authorized to use, without visibility into other network resources.

This segmentation isolates sensitive systems, reducing the risk of lateral movement if a user or device is compromised. It also helps organizations comply with regulatory frameworks by enforcing strict, application-level access boundaries and minimizing the scope of compliance audits.

3. Dynamic Access Policies

ZTNA evaluates a wide range of contextual factors when making access decisions. Policies can include parameters like user identity, role, device type, device health, geographic location, time of day, and recent user behavior. This contextual awareness helps prevent unauthorized access and adapts to changing risk levels.

Access decisions aren’t static. ZTNA systems continuously reassess sessions, modifying or revoking access if risk conditions change—for example, if a device falls out of compliance or a user’s behavior deviates from normal patterns. This real-time policy enforcement reduces exposure to emerging threats.

4. Encrypted Connections via ZTNA Broker

Once authentication and policy checks are complete, user traffic is routed through a ZTNA broker or gateway. This broker sits between the user and the application, acting as a control point for inspecting and enforcing access policies. The connection between the user and the broker—and between the broker and the application—is fully encrypted, often using TLS.

This architecture ensures that users never establish direct network-layer connections to backend resources. All communication flows through the broker, reducing exposure and preventing attackers from scanning or directly targeting the network infrastructure.

5. Continuous Monitoring and Risk Assessment

ZTNA solutions include continuous monitoring to track user behavior, device status, and environmental factors throughout the session. If suspicious activity is detected—such as a sudden change in location, unusual access patterns, or a drop in device security posture—the system can trigger automated responses.

These responses may include step-up authentication, reduced access privileges, or immediate session termination. Continuous risk assessment helps organizations enforce adaptive security measures and respond quickly to evolving threats without waiting for periodic audits or manual reviews.

Related content: Read our guide to zero trust architecture

ZTNA vs. VPN vs. SDP

Zero Trust Network Access (ZTNA), Virtual Private Networks (VPNs), and Software-Defined Perimeters (SDPs) are all technologies designed to secure remote access, but they differ significantly in architecture, security posture, and operational model.

ZTNA vs. VPN

VPNs extend a private network across the internet, allowing users to access internal resources as if they were on the local network. However, VPNs typically grant broad network-level access after a single authentication event, which creates substantial lateral movement risk if credentials are compromised. VPNs also lack granular visibility and control over user actions once inside the network.

ZTNA, in contrast, does not place users on the internal network at all. Instead, it connects authenticated users directly to specific applications through a secure broker, based on granular access policies. This minimizes attack surfaces, reduces lateral movement, and aligns with least-privilege principles.

ZTNA vs. SDP

SDP is a precursor to ZTNA that also operates on a zero-trust principle, focusing on concealing infrastructure and making it accessible only after verification. It uses a control plane to authenticate and authorize access, and a data plane to facilitate secure connections between users and services.

ZTNA builds on SDP concepts but typically adds broader integration with identity providers, richer contextual policy enforcement, continuous monitoring, and cloud-native scalability. Some definitions even consider ZTNA a commercial implementation or evolution of the SDP model.

In summary, VPNs offer basic remote access but pose security risks due to broad access and weak segmentation. SDPs introduced the concept of cloaked access, while ZTNA extends this model with adaptive, context-aware controls and stronger integration into modern IT ecosystems.

Key ZTNA Use Cases

1. Multi-Cloud and Hybrid Environments

ZTNA is effective in multi-cloud and hybrid environments where applications and data reside across several platforms and locations. It enables secure access policies that span on-premises data centers, public clouds, and SaaS providers, regardless of where the user is located. This flexibility is essential for organizations operating in varied environments, ensuring consistent security controls without the complexity and risk of traditional network segmentation.

With centralized policy management and continuous verification, ZTNA eliminates the need for direct connectivity between cloud resources and user endpoints. Traffic is always brokered, reducing the attack surface and avoiding exposed services. This approach simplifies compliance efforts and forensic investigations by routing all access through a single, policy-driven point.

2. Third-Party and Partner Access

Granting access to third-party vendors, contractors, or business partners poses significant risk if not properly secured. ZTNA allows organizations to offer tightly controlled, transitory access tailored to each external user’s specific needs. Unlike traditional VPNs, which often provide far-reaching privileges once access is granted, ZTNA restricts users to only the applications and data explicitly allowed by policy.

ZTNA also abstracts applications from the broader network, so partners cannot see or probe systems outside their scope. When their engagement ends, their access can be instantly revoked without affecting the internal network or requiring complex firewall modifications.

3. Remote Workforce and BYOD

Remote work and bring your own device (BYOD) programs introduce unmanaged assets onto the corporate network, complicating access controls. ZTNA addresses these challenges by verifying both user identity and device posture for every session, ensuring only secure devices can connect to sensitive applications. This prevents infected, outdated, or noncompliant devices from becoming attack vectors.

ZTNA’s focus on application-level access, rather than broad network privileges, means employees working from anywhere remain productive while risks are minimized. It provides the flexibility to support diverse device types without exposing internal resources to potential threats.

4. Merger and Acquisition (M&A) Integration

Integrating new users, networks, and applications after a merger or acquisition is fraught with security risks, especially when legacy systems and overlapping directories are present. ZTNA enables rapid, granular onboarding by authorizing access based on identity and context, without requiring network-level trust or full consolidation. This helps organizations impose least-privilege policies from day one, reducing the attack surface and potential for accidental exposure.

Because ZTNA operates independently of physical network topology, organizations can manage access to critical applications and IP even as they rationalize or migrate inherited infrastructure. This streamlines integration processes and mitigates risks posed by unknown or legacy systems until comprehensive reviews and controls are in place.

Suggested additional reading: Browser Security

Types of ZTNA Solutions

Here are a few technical approaches behind today’s ZTNA solutions and their pros and cons.

Agent-Based

Agent-based ZTNA solutions require users to install a dedicated software agent on their endpoint devices. This agent continuously communicates with the ZTNA controller, providing detailed insights into device posture, including operating system version, installed security patches, running processes, and compliance with security policies. By leveraging this granular data, organizations can enforce dynamic access controls that respond to real-time device conditions, ensuring that only compliant and secure devices gain access to applications.

While agent-based ZTNA can offer superior visibility and fine-grained policy enforcement, it comes with challenges related to deployment and management across large or heterogeneous device fleets. Installation, updates, and ongoing maintenance of agents can stretch IT resources, particularly in BYOD or third-party scenarios.

Agentless

Agentless ZTNA solutions leverage browser or web-based technologies to enforce access controls, eliminating the need for software installation on endpoints. This makes them ideal for accommodating third parties, contractors, or non-corporate devices where agent deployment is impractical or impossible. Most agentless ZTNA approaches use reverse proxies or identity-aware gateways to authenticate users and devices and mediate access to web applications.

Although agentless ZTNA simplifies onboarding and supports a broader range of devices, it may not provide the same depth of device posture assessment as agent-based methods. Controls are usually limited to web applications since native or legacy applications may not be easily protected without an agent.

Cloud-Native

Cloud-native ZTNA solutions are built to integrate seamlessly with cloud infrastructure, both public and private. These platforms leverage cloud scalability, elasticity, and distributed enforcement points to provide consistent policy application regardless of user location. Organizations adopting SaaS and IaaS benefit from simplified management, automatic updates, and reduced hardware dependencies, all while extending secure access controls across geographically dispersed resources.

By using cloud-native architectures, ZTNA providers can support rapid onboarding, API-driven automation, and deep integration with identity providers, SIEM, and other cloud-based security solutions. However, reliance on internet connectivity, handling sensitive data in third-party clouds, and navigating complex regulatory environments can introduce risks that must be balanced with the operational gains cloud-native ZTNA brings.

Hybrid

Hybrid ZTNA solutions combine on-premises and cloud-based deployment options, accommodating organizations with complex IT environments, legacy applications, or regulatory requirements that preclude fully cloud-based security solutions. Hybrid models allow critical or sensitive workloads to remain on-premises, while extending ZTNA controls to cloud resources and remote users through cloud-delivered components.

This approach gives organizations the flexibility to transition at their own pace, ensuring consistent security and user experience across hybrid architectures. Hybrid ZTNA requires thoughtful integration between on-premises controls and cloud services, but it helps organizations maintain compliance, support legacy apps, and avoid network disruptions common in large-scale migrations.

Best Practices for Successful ZTNA Adoption

1. Adopt a Zero-Trust Mindset Throughout the Organization

Adopting ZTNA is not just about implementing new technologies—it requires a shift in organizational culture and mindset. Every employee, from executives to end users, should understand that the security model is based on skepticism, not trust. This means routinely questioning access requests, validating identities, and defaulting to least-privilege principles. Clear communication and change management initiatives are essential to break down old habits associated with perimeter-focused security.

Successful ZTNA adoption involves collaboration between security, network, and business teams to define access policies, risk tolerance, and compliance requirements. Leadership must champion zero-trust principles and allocate resources to support ongoing training and awareness. Establishing metrics for adoption, understanding resistance points, and continuously reinforcing the importance of identity-based access ensures that the zero-trust philosophy becomes part of everyday operational thinking.

2. Use Strong MFA and Device Posture Checks

ZTNA depends on robust multi-factor authentication (MFA) and continuous device posture assessments to validate every access attempt. Strong MFA binds user identity to a combination of credentials, such as biometrics, tokens, or one-time passcodes. Coupling MFA with device posture ensures that only secure, up-to-date endpoints are permitted, halting threats like malware, outdated software, and misconfigured devices.

Organizations should regularly review their MFA implementations for coverage gaps, user experience issues, and potential bypasses. Device posture checks must be continuously updated to reflect emerging threats and align with organizational security standards. Automated remediation—such as prompting users to update software or block risky devices—strengthens overall posture without undue administrative overhead.

3. Segment High-Value Assets with Microsegmentation

Microsegmentation is a key enabler of least-privilege access and lateral movement prevention in ZTNA. By creating small, well-defined security zones within and between application environments, organizations can tightly control who and what can communicate with critical assets. Instead of broad, flat networks, each application or database gets its policy-driven boundary, reducing containment radius if a compromise occurs.

Designing effective microsegmentation requires upfront discovery, inventory, and classification of applications and data flows. Automated tools can map dependencies and assign logical segments. Continuous monitoring ensures policies adapt to changes in business operations, and integration with ZTNA workflows keeps access controls in sync with organizational evolution and risk changes.

4. Automate Policy Updates and Access Reviews

ZTNA environments generate large volumes of access and activity data, providing a rich source for automated policy enforcement and review. Automation helps organizations enforce timely policy updates, revoke privileges, and respond to newly discovered threats without manual intervention. Periodic, automated access reviews ensure that users retain only the permissions relevant to their current role or responsibilities.

In addition to policy automation, organizations should integrate ZTNA with security orchestration, identity management, and incident response platforms. This allows for rapid adaptation to evolving security requirements and threat landscapes.

5. Plan for Continuous ZTNA Evolution

ZTNA is not a one-and-done project; it’s an ongoing process that must evolve with the organization’s needs, threat landscape, and technology stack. Regularly revisit risk models, threat intelligence, compliance guidelines, and access policies to ensure they reflect current realities. This means updating identity sources, integrating new applications, and adjusting device posture requirements as threats and operations change.

Organizations should adopt an iterative approach by collecting feedback from users and IT, measuring effectiveness, and applying lessons learned to refine policies and processes. Engaging in continuous improvement helps maintain alignment with business objectives and regulatory obligations.

Implementing ZTNA in Browser Environments with Seraphic Security

As organizations continue migrating critical applications and data to the cloud, browsers have effectively become the new endpoint. Traditional ZTNA solutions typically focus on securing network and application layers, but often overlook the browser, which is the primary gateway for users accessing SaaS platforms, internal apps, and web resources. This creates a blind spot for security teams, leaving sensitive data and sessions exposed to modern web-based threats, including zero-day attacks, session hijacking, and malicious extensions.

Seraphic Security bridges this critical gap by embedding ZTNA principles directly into the browser environment itself. Unlike proxy-based or isolated browser solutions that add latency and disrupt user workflows, Seraphic integrates seamlessly with any browser, providing granular access controls, continuous session protection, and policy enforcement in real time. It ensures that access to applications and resources is authenticated, authorized, and continuously verified — not just at the point of entry, but throughout the entire session.

With Seraphic, security teams can extend Zero Trust principles to managed and unmanaged devices without the need for VPNs, VDI, or complicated infrastructure changes. Employees, contractors, and third-party users can securely access corporate resources through their native browsers, while organizations maintain full visibility, control, and protection against evolving browser-based threats. This modern approach to ZTNA not only strengthens security posture but also preserves a frictionless, intuitive user experience.

For more information visit Seraphic Security.