Is Network Security Still Relevant in a Zero Trust World?

Bill Nystrom
Bill Nystrom
March 19, 2024 • 10 min read
Is Network Security Still Relevant in a Zero Trust World?

In an age where cyber threats loom large over national security and the digital infrastructure of the defense sector, the adoption of the Zero Trust model has emerged as a strategic imperative. This paradigm shift, away from traditional perimeter-based defenses to a more dynamic, data-centric approach, is redefining the contours of the global cybersecurity industry.

While much of the discourse around Zero Trust focuses on its revolutionary approach to security, there’s a familiar hero quietly underpinning its success: network security. Far from being rendered obsolete, network security is experiencing a renaissance, proving itself to be the linchpin in the successful implementation of Zero Trust architectures. 

The Paradox of Visibility in a Trustless World

Zero Trust challenges the traditional security model by asserting that blind trust is a vulnerability. In a world where breaches can originate from anywhere, the importance of visibility and control over network traffic cannot be overstated. Network security transcends its conventional function of restricting unauthorized access to network resources and data at the perimeter, by shifting to a more dynamic role in the Zero Trust framework, where it becomes the engine for actively monitoring, segmenting, and controlling all digital interactions in response to a dynamic threat environment based on adaptive policy considerations. By providing comprehensive visibility into all network traffic, network security tools enable organizations to implement granular access controls and policies that are central to the Zero Trust ethos. Modern network security, in other words, isn’t just about erecting barriers; it’s about creating a dynamic, responsive security environment that adapts in real-time to threats, ensuring that verification is continuous and comprehensive. 

The Zero Trust Model: A Brief Overview

Zero Trust is predicated on the assumption that threats can originate from anywhere—both outside and inside traditional network perimeters. This model advocates for a “never trust, always verify” approach, requiring authentication and authorization for every user and device attempting to access resources on a network, regardless of their location.

Traditional security architectures often rely on perimeter-based defenses, such as firewalls and intrusion detection systems, operating under the assumption that everything inside the network is trustworthy, whereas threats predominantly come from outside the network. This model creates a trusted internal zone and an untrusted external zone, but once inside, users and devices typically have broad access, potentially exposing the network to insider threats or lateral movements from compromised credentials.

In contrast, ZTA eliminates the concept of a trusted internal network. Instead, individualized connections are established between user and data source dynamically based on policy, risk, and threat profile. This means that enabling Zero Trust requires continuous verification of the identity and security posture of each user and device attempting to access resources within the network, regardless of their physical or network location. This approach applies granular access controls and least privilege principles, ensuring users and devices have access only to the resources necessary for their specific roles and functions.

NIST’s Special Publication 800-207 on Zero Trust Architecture provides a comprehensive framework, emphasizing the minimization of trust zones and the enforcement of strict access controls. 

Network Security’s Role in Zero Trust

At its core, network security involves ensuring the confidentiality, integrity, and availability of the network to access data. Traditional network security typically operates on a model where segmentation is achieved through static, predefined mechanisms such as virtual local area networks (VLANs), virtual routing and forwarding (VRF) instances, and subnets. These methods create broad, fixed segments within the network, each governed by its own set of access controls and security policies. This model assumes that once granted access to a specific network segment, all users and devices are essentially at the same privilege level and can be permanently trusted to access any resource on that segment. This concept falls short in today’s dynamic and threat-prone digital landscape. The segmentation is generally inflexible and administratively intensive to maintain, making it challenging to adapt quickly to changes in network traffic patterns, user needs, or emerging threats.

Micro-segmentation represents a significant evolution in network security, moving away from these static, broad segments to highly dynamic, fine-grained access control. Unlike traditional methods, micro-segmentation establishes secure, temporary communication paths on a per-session basis, directly between the user and the specific resources or data they are authorized to access. This approach leverages real-time policy enforcement, risk assessment, and threat intelligence to determine access rights, dynamically adjusting permissions based on the context of each request.

This evolution enables a more adaptive and secure network environment, where any user can connect to any resource and access any data, but strictly according to the current policy, assessed risk, and identified threats. By doing so, micro-segmentation eliminates implicit trust once granted within the network perimeter, aligning perfectly with the Zero Trust principle of “never trust, always verify.” For network engineers, this shift means that they can now provide flexible, immediate access to network resources while maintaining rigorous security controls, ensuring that the network’s integrity is preserved even in the face of sophisticated cyber threats. This model not only bolsters security but also better supports the needs of modern distributed workforces, multi-cloud environments, IoT, and advanced mobility requirements.

While Zero Trust may seem to overshadow traditional security measures, it actually elevates the role of network security in several key areas:

1.   Enhanced Visibility and Micro-Segmentation: In a Zero Trust framework, the ability to identify, grant access, and exert control over every network resource is critical. Next-generation firewalls and policy enforcement points are being combined and integrated into secure access service edge (SASE) platforms that provide deep visibility and facilitate the rapid micro-segmentation sessions critical for identifying and isolating threats, thereby reducing the attack surface and enhancing the overall security posture.

2.   Dynamic and Adaptive Access Controls: Adversaries excel at exploiting the static nature of a given enterprise network. Once they gain initial access and perform exhaustive reconnaissance they are able to hide out in the network and wait for the most opportune time to launch an attack. They typically can do this because the traditional network seldom, if ever, changes. Modern network security technologies are now being equipped with advanced analytics and machine learning capabilities that enable anomaly detection, real-time decision-making, and enforcement of access controls. This adaptability is crucial for maintaining operational continuity and protecting sensitive information in fluid threat environments.

3.   Secure Connectivity Across Disparate Environments: As business operations become increasingly reliant on cloud-based services, IoT devices, and remote access, securing these interconnections is essential. Network security solutions such as Zero Trust gateways enable micro-parameters to facilitate all network interactions to ensure that data remains secure, regardless of where it is accessed or stored.

4.   Compliance and Risk Assessment: Adhering to the stringent compliance requirements across regulated industries, such as the defense sector, is non-negotiable for both government agencies and government contractors processing data or providing applications accessed by government entities. Network security practices play a pivotal role in continuous monitoring and compliance assessment, ensuring that defense networks meet the rigorous standards set forth by Zero Trust policies. Continuous monitoring requires careful integration of technologies such as security information and event management (SIEM) systems, intrusion detection systems (IDS), and intrusion prevention systems (IPS). These systems work in unison to provide real-time surveillance of network traffic and user behavior to identify anomalies indicating an elevation of threat to mitigate an ongoing breach. SIEM systems then aggregate and correlate data from diverse sources across the network, enabling the Security Operations Center to respond, remediate, and reconfigure the network infrastructure to resume normal operations. Security logs, reports, and other artifacts are then fed into the cyber risk management platform using a variety of automated means to ensure policy compliance and risk posture.  

Separating the Data and Control Planes

Zero Trust Architecture would not have been possible without the power of modern software-defined networking (SDN). Software-defined networking (SDN) is a network architecture approach that separates the network’s control plane from the data plane, enabling programmable management and optimization of network resources through software-based controllers or application programming interfaces (APIs). Even with an organization achieving full Zero Trust Architecture (ZTA) implementation, spanning any data source to any clients across any network, the underlying truth remains: the efficacy of ZTA hinges on securing the control plane (meaning: the management of network traffic and how data is sent from one place to another) through advanced network security principles. Zero Trust is enabled by secure communication of core devices such as policy decision points (PDP), policy enforcement points (PEP), Identity, Credential, and Access Management (ICAM) servers, public key infrastructure (PKI) servers, encryption devices, and cybersecurity systems that form the backbone of ZTA.

However, without the application of sound network security principles to protect these elements, the integrity of the entire architecture is at risk. Ensuring ZTA policy and control devices are secure is essential to keeping the entire framework robust and responsive. Securing the control plane is critical as it holds the keys to the network’s overall management and configuration, dictating how data packets are routed and handled. A compromise here can lead to widespread network disruption and unauthorized access, making it a prime target for attackers seeking to exploit network vulnerabilities.

The Road Ahead: Network Security in the Spotlight

Looking ahead, the integration of emerging technologies such as artificial intelligence and machine learning into network security operations promises to enhance the effectiveness of Zero Trust architectures, offering new ways to detect, respond to, and preempt cyber threats. In the narrative of cybersecurity, Zero Trust has taken center stage, promising a future where security is more dynamic, intelligent, and effective.

However, it’s essential to recognize the critical role of network security in this narrative. As the foundation upon which Zero Trust is built, network security is not just a component of the framework but rather the very essence of its effectiveness. By ensuring the visibility, adaptability, and security of our networks, network security stands as the unseen guardian in a world where trust is a liability.

As we look to the future, the collaboration between Zero Trust principles and network security technologies will continue to be a cornerstone of effective cybersecurity strategies. As the threat landscape evolves and tactics, techniques, and procedures are formed to respond, it is clear that core network security principles will also continue to adapt and evolve to meet the challenge.

Network Security is Dead! Long Live Network Security!

The journey toward a fully realized Zero Trust architecture for the average enterprise is long and full of peril. However, the path forward is clear, requiring one step at a time. Solid network security is not merely a waypoint on the Zero Trust journey; it is the hiking boots that enable you to more effectively navigate the terrain.

In this era of unyielding cyber threats, understanding and leveraging the relationship between network security and Zero Trust is not just strategic; it’s foundational.  Mark Twain once said, “The report of my demise has been greatly exaggerated.” The same can be said about network security. The fact is that Zero Trust does not kill network security; it elevates it.

Bill Nystrom
Bill Nystrom
Chief Technology Officer
Bill Nystrom is Chief Technology Officer at Telos Corporation.
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