Security Models Demystified

Ben Rees, Senior Network Product Engineer | Estimated Read Time: 10 minutes

Security models demystified: Zero trust, SASE, and shared responsibility

Security models provide the foundation of how organisations protect their data, applications, and infrastructure. Yet for many technical leaders, the gap between security theory and practical implementation feels impossibly wide.

If you're a CIO or Head of Infrastructure wrestling with compliance requirements, multi-cloud connectivity, or legacy vendor limitations, you've likely encountered this frustration: security models that sound straightforward on paper become maddeningly complex when applied across hybrid environments.

This guide cuts through the confusion. We'll explore the major security models shaping modern network architecture, reveal why organisations struggle to implement them consistently, and show how the right approach to secure connectivity can turn security principles into operational reality.

Why security models matter more than ever

Modern organisations face a perfect storm of security challenges. Cyber attacks are escalating across all sectors. Remote working has expanded the attack surface. Legacy infrastructure sits alongside cloud services. And compliance requirements demand rigorous, auditable security controls, whether you're bound by industry regulations, data protection laws, or internal governance standards.

Security models provide the conceptual framework for addressing these challenges. But here's the problem: most organisations are juggling multiple models simultaneously. You might be implementing zero trust principles for user access, adopting SASE for branch connectivity, and managing shared responsibility across AWS, Azure, and on-premises data centres, all whilst maintaining audit trails for ISO 27001 compliance.

Without a unified approach to apply these models consistently, you end up with security gaps, operational overhead, and compliance headaches.

The major security models: What they are and why they matter

Zero trust: "Never trust, always verify"

Zero trust assumes that threats exist both inside and outside the network perimeter. Rather than trusting any user or device by default, zero trust requires continuous verification of identity, device health, and context before granting access to resources.

Traditional perimeter-based security (the "castle and moat" approach) fails in hybrid environments where users, applications, and data exist across multiple locations. Zero trust provides a framework for securing access regardless of where resources live or where users connect from.

Core principles:

• Verify explicitly using all available data points (identity, location, device health, workload classification)

• Apply least privilege access: grant only the minimum permissions needed

• Assume breach and segment networks, monitoring continuously to contain potential compromises

For organisations managing sensitive data alongside cloud services, zero trust principles are essential. An employee accessing customer records from home requires the same rigorous verification as a contractor connecting to the network, regardless of their location or device.

SASE: Converging network and security

Secure Access Service Edge (SASE) combines software-defined wide area networking (SD-WAN) capabilities with comprehensive security services, including SWG (Secure Web Gateway), CASB (Cloud Access Security Broker), FWaaS (Firewall as a Service), and zero trust network access, delivered from the cloud as a unified service.

SASE addresses the fundamental challenge of modern networking: organisations no longer have a single, defined perimeter. Users, applications, and data are distributed across branch offices, remote workers, multiple clouds, and legacy data centres. SASE provides security that follows users and workloads rather than being anchored to fixed locations.

Key benefits:

• Consistent security policy enforcement regardless of where users or applications reside

• Reduced complexity by consolidating multiple security tools into a single platform

• Improved performance through cloud-delivered security services closer to users

For organisations with multiple sites, remote workers, and cloud migrations underway, SASE principles help unify security and connectivity in a way that traditional approaches simply can't match.

Shared responsibility model: Who secures what in the cloud?

The shared responsibility model defines the division of security obligations between cloud providers and their customers. The provider secures the infrastructure (physical security, hypervisor, network infrastructure), whilst customers secure everything they put into the cloud (data, applications, identity management, access controls).

Misunderstanding shared responsibility causes many cloud security failures. Organisations assume their cloud provider handles security comprehensively, only to discover (often after an incident) that data protection, access management, and application security remain their responsibility.

The dividing line:

• Cloud provider responsibility: Physical security, infrastructure, virtualisation layer, managed services (when fully managed options are selected)

• Customer responsibility: Data encryption, identity and access management, application security, operating system patching, network traffic protection, compliance controls

For organisations moving sensitive data to Azure or AWS, understanding where your compliance obligations sit within the shared responsibility model is critical. The cloud provider won't configure your network security groups, manage your encryption keys, or ensure your access controls meet regulatory requirements. Those are your responsibilities.

Defense in depth: Layered security

Defense in depth applies multiple layers of security controls throughout an IT environment. If one layer fails, others remain to prevent or limit damage. This might include perimeter firewalls, network segmentation, endpoint protection, application security, data encryption, and security monitoring, each providing an independent barrier.

No single security control is foolproof. Defense in depth ensures that a vulnerability in one area doesn't compromise your entire environment. For organisations handling sensitive data, this layered approach is often essential for both security and compliance.

Applied practically:

• Perimeter security (firewalls, DDoS protection)

• Network security (segmentation, IDS/IPS)

• Endpoint security (antivirus, EDR)

• Application security (WAF, secure coding)

• Data security (encryption at rest and in transit)

• Identity security (MFA, privileged access management)

Why organisations struggle to apply security models consistently

Understanding security models is one thing. Implementing them across hybrid, multi-cloud, and legacy environments is entirely different.

Challenge 1: Fragmented visibility across environments

When your network spans on-premises data centres, multiple cloud providers, branch offices, remote workers, and various connectivity requirements, achieving consistent visibility becomes nearly impossible.

Each environment has its own monitoring tools, logging formats, and dashboards. Your AWS VPC flow logs look nothing like your Azure Network Watcher data, which differs entirely from your on-premises SIEM feeds. Correlating security events across these fragmented views requires significant manual effort or goes undone entirely.

Without unified visibility, security models can't be applied effectively. Zero trust requires continuous monitoring of user behaviour and access patterns. SASE depends on real-time traffic analysis. Shared responsibility demands clear audit trails. When you can't see what's happening across your entire infrastructure, these models remain aspirational rather than operational.

Challenge 2: Inconsistent policy enforcement

Traditional security architectures enforce policies at fixed points, typically the perimeter firewall or data centre gateway. In hybrid environments, there is no single perimeter.

Users accessing resources directly from home bypass corporate security controls. Applications in AWS communicate with databases in Azure through peering connections that may not traverse your security stack. SaaS tools are accessed directly from user devices without any visibility into what data is being shared.

Security policies that work perfectly in your data centre become impossible to enforce consistently across cloud and remote access scenarios. This inconsistency creates both security gaps and operational headaches as teams struggle to implement the same security principles using different tools and approaches for each environment.

Challenge 3: Operational complexity and skills gaps

Implementing security models properly requires deep expertise across networking, security, identity management, and compliance. For many organisations, this expertise is often in short supply.

Even when skills exist, the operational burden is substantial. Managing separate security tools for each environment (cloud-native security groups in AWS, NSGs in Azure, traditional firewalls for on-premises, VPNs for remote access) requires constant attention, configuration drift management, and troubleshooting when things break.

Every new security tool adds licensing costs, training requirements, and integration challenges. Teams become overwhelmed trying to maintain consistency across fragmented security infrastructure whilst simultaneously responding to incidents and addressing compliance audit findings.

Challenge 4: Legacy infrastructure and vendor lock-in

Many organisations are trapped with legacy network vendors that were never designed for cloud-era security. Long contract terms, inflexible architectures, and slow deployment times make it nearly impossible to adapt security controls as your environment evolves.

When you want to implement zero trust access for a new cloud application, but your legacy VPN vendor requires a three-month lead time for configuration changes, security theory meets operational reality, and theory loses.

Similarly, vendor lock-in with traditional telcos or managed service providers often means you're constrained to their security toolset, their timelines, and their approach, regardless of whether it fits your security model requirements.

Common misconceptions about cloud security responsibilities

Misconception 1: "The cloud provider handles security"

Cloud providers secure the infrastructure. Your data, applications, and access controls remain your responsibility. You must configure security groups, manage encryption, control access, and ensure compliance with regulatory requirements.

This misconception leads to exposed databases, misconfigured storage buckets, and compliance failures. The cloud provider gives you the tools, but you must use them correctly.

Misconception 2: "Zero trust means we don't need perimeter security"

Zero trust complements perimeter security rather than replacing it. You still need firewalls, DDoS protection, and network segmentation. Zero trust adds continuous verification and least privilege access on top of these foundational controls.

Implementing zero trust means applying verification at every access point whilst maintaining robust perimeter defenses. Both layers work together.

Misconception 3: "SASE eliminates the need for on-premises security"

SASE is powerful for securing cloud and remote access, but most organisations will maintain hybrid environments for years. On-premises data centres, legacy applications, and specific compliance requirements mean you'll likely need both SASE and traditional security controls working together.

The goal is to create a consistent security posture that spans both traditional and cloud-native environments.

Misconception 4: "Compliance equals security"

Meeting compliance requirements (ISO 27001, Cyber Essentials Plus, PCI DSS) demonstrates baseline security controls, but compliance checklists don't guarantee protection against sophisticated threats.

Security models like zero trust and defense in depth go beyond compliance requirements to address real-world attack scenarios. Compliance is necessary but not sufficient. You need both the audit trail that satisfies regulators and the operational security that stops actual threats.

How Cloud Gateway enables practical security model implementation

At Cloud Gateway, we've built our platform to help organisations apply security models effectively across hybrid and multi-cloud environments.

Unified visibility across your entire infrastructure

Our platform provides a single pane of glass for monitoring connectivity, security, and traffic flows across all environments: cloud, data centre, branch offices, remote users, and internet connectivity.

Real-time network analytics, threat intelligence integration, and comprehensive logging give you the visibility required to implement zero trust principles. You can see who's accessing what, from where, and whether their behaviour matches expected patterns. SIEM and SOC integration ensures your security operations team has the audit trail needed for both incident response and compliance reporting.

When you can see everything happening across your infrastructure from a single portal, security policies move from theoretical frameworks to enforceable reality.

Consistent policy enforcement through integrated security

Cloud Gateway unifies network connectivity and security services into a single platform. Next-generation firewalls with DPI, IPS/IDS, and anti-malware capabilities protect traffic regardless of where it originates or terminates. Secure Web Gateway filters internet access for remote users. WAF protects public-facing applications.

Because these security services are built into the connectivity platform, policies are applied consistently. A user accessing a cloud application from home receives the same security inspection as someone in the office accessing an on-premises system. Traffic between your AWS and Azure environments traverses the same security stack as your other network traffic.

This integrated approach makes SASE principles practical. Security follows workloads and users rather than being anchored to fixed locations. You don't need separate security stacks for each environment. One platform applies your security policies everywhere.

Simplified operations with full managed service

We deliver Cloud Gateway as a fully managed service, handling design, deployment, monitoring, and support. This addresses the skills gap and operational complexity that prevent many organisations from implementing security models effectively.

Our network and security experts ensure your environment is configured correctly, monitor for threats and anomalies, and respond to incidents. You benefit from defense in depth without needing to become an expert in every security technology. Auto-updating threat intelligence from industry-leading vendors keeps your protections current without manual intervention.

For organisations that want more control, self-serve features in the platform allow you to provision services, adjust policies, and monitor performance yourself, safe in the knowledge our team is available when needed.

Flexible, compliance-ready connectivity

Cloud Gateway is built to support stringent compliance requirements across multiple industries and regulatory frameworks. Our UK-based infrastructure ensures data sovereignty for organisations with geographic data residency requirements.

Our platform supports the shared responsibility model by giving you the tools and visibility needed to fulfil your security obligations in cloud environments. Granular access controls, encryption, audit logging, and compliance reporting help you demonstrate to auditors that you're managing your responsibilities effectively.

Short contract terms and OPEX-centric pricing eliminate vendor lock-in, giving you flexibility to adapt your security architecture as your environment and threats evolve.

Translating theory into practice: A path forward

Security models don't need to remain abstract frameworks that gather dust in strategy documents. With the right approach to connectivity and security, you can translate principles into operational reality:

Start with visibility. You can't secure what you can't see. Unified monitoring across hybrid environments gives you the foundation for every security model.

Unify policy enforcement. Consistent security controls across cloud, on-premises, and remote access scenarios turn security models from aspirations into enforceable policies.

Simplify operations. Managed services and integrated platforms reduce the operational burden and skills gap that prevent effective security model implementation.

Build for flexibility. Avoid vendor lock-in and rigid architectures. Your security needs will evolve as threats change and your organisation transforms digitally.

Security models exist because they work. Zero trust prevents lateral movement after a breach. SASE provides consistent protection regardless of where users and workloads reside. Shared responsibility clarifies cloud security obligations. Defense in depth ensures no single vulnerability compromises your entire environment.

The challenge sits in implementing these models consistently across the complex, hybrid infrastructure that defines modern enterprise IT.

At Cloud Gateway, we make security models practical. Our platform gives you the visibility, integrated security, and operational support needed to protect sensitive data, maintain compliance, and enable secure digital transformation without adding complexity.

We're a trusted partner helping you translate security theory into reliable, compliant, operational reality.

Ready to move beyond security frameworks and implement practical protection across your hybrid environment? Let's talk about how Cloud Gateway can help.