A zero-trust security model for the edge systems

As zero-trust security models become the default approach for cybersecurity, why is it important for the defense sector to adopt?

In 2021, Executive Order 14028 was issued, aiming to modernize the federal government’s cybersecurity standards, to increase threat information sharing between the government and the private sector, and to improve software supply chain security.

Specifically, the order outlined the plan to apply zero trust in federal agencies, stating “the Zero Trust security model eliminates implicit trust in any one element, node, or service and instead requires continuous verification of the operational picture via real-time information from multiple sources to determine access and other system responses.”

Here, we will examine what zero-trust principles are most relevant to non-enterprise, edge technology — the embedded mission computers, sensors and control systems running radars, drones, cell towers, traffic control and industrial infrastructure across defense and commercial settings — the benefits it should bring to various industries and its customers, and edge-specific considerations when applying the model.

Zero trust and defense technology

Principles of zero trust that are pertinent to non-enterprise, edge environments include:

1.       Microsegmentation: A system is separated into smaller units or domains to limit the risk radius, and different security requirements for separate domains are applied based on risk and information sensitivity. For example, control or management planes should be separated from operational domains, such as a drone’s sensor capabilities and its control system, and they also should be isolated from other domains to allow for degraded operations should one domain become compromised.

2.       Least-privilege access: Processes are granted the minimum necessary access to resources based on their need-to-operate. This includes limiting the configurations/switches that many processes rely upon when executed. 

3.       Data security: Data must be protected at rest, in transit, and in use through access controls, encryption, and security technologies.

4.       Device and workload identity and attestation: With edge devices, computing happens on telecommunications infrastructure, vehicles, medical devices, or other forward-deployed systems, enabling decisions and analysis without requiring distant infrastructure such as a data center. This requires anchoring trust via machine identity and proving the device is in a provable known-good state. Using hardware-rooted identity such as a trusted platform modules (TPM) along with secure/measured boot and cryptographic attestation ensures only authorized devices and verified workloads can join the enclave and run critical functions.

5.       Run-time integrity and anomaly detection: Detecting changes to code, processes, configuration, or behavior while a system is running requires lightweight integrity checks that can operate on limited compute and unreliable network links. These checks include continuously validating run‑time state via firmware and kernel integrity, workload allowlisting, and configuration drift, and also detecting suspicious behavior like unexpected processes, privilege changes, unusual network flows, or sensor spoofing.

What benefits does zero trust bring to the defense sector?

The non-enterprise defense sector maintains sensitive information that should be accessible only to those with a need-to-know even if the information is lost during battle. The zero-trust model follows this philosophy, limiting and verifying processes to keep critical information secure and keep information access limited, no matter the user. This least-privileged access standard also helps secure supply chains and ensure continuity by mitigating risks with suppliers and partners.

Zero-trust security also helps organizations meet National Institute of Standards and Technology (NIST) and Cybersecurity Maturity Model Certification (CMMC) regulations: microsegmentation maps to CMMC access control and configuration management practices and NIST SP 800-207, least-privilege access maps to CMMC access control practices and NIST SP 800-53, and continuous monitoring maps to CMMC audit, accountability and security assessment requirements and NIST SP 800-53.

Although the government prioritizes zero trust to protect sensitive information, the model’s importance has wider echoes, as it is fundamental to mission success and continuity. Zero trust goes beyond data protection, ensuring that critical systems and networks are built to withstand, identify, and recover from attacks.

Special zero-trust security model considerations

Commercial and defense organizations face unique security challenges that must be considered when adopting any security approach, including zero trust. These include:

·       Complex and distributed environments: Commercial and defense sectors are spread across multiple domains — physical locations, mobile platforms, space, and cyberspace — using differing technology, databases, and communications platforms. Many of these systems also operate disconnected or degraded for extended periods: a shipboard system or forward-deployed platform that goes weeks without a link home can’t lean on the continuous, real-time verification an office network takes for granted. Zero-trust decisions have to be evaluated locally, using policy and identity anchored at build time, rather than brokered by a service that may be unreachable when it matters most.

·       Legacy systems and mindsets: Commercial and defense systems can often be older and integrated into multiple other systems of differing ages and sophistication — mission equipment is frequently fielded for a decade or more without a hardware refresh, on platforms where replacing it outright isn’t an option. That means adoption has to be phased, not wholesale. Creating zero-trust enclaves — isolating certain critical legacy systems with zero-trust controls — can help initial adoption. Beyond the technical work, training and user buy-in are essential to shifting mindsets away from a traditional perimeter security approach.

·       Supply chain security: Sectors such as manufacturing, technology, and communications can all be part of an edge system’s supply chain, and a compromise anywhere in that chain can undermine zero-trust guarantees built everywhere else. That risk deserves its own treatment — see our companion piece on zero trust and the software supply chain for how these principles apply to vendors, components and code.

·       Data sensitivity and compliance: Edge systems handle data across a wide range of sensitivity levels and compliance regimes — unclassified operational data alongside classified or ITAR-controlled information, sometimes on the same platform. That mix calls for cross-domain solutions and classification-aware access controls, not a single data-protection policy applied uniformly across every system.

Zero trust is critical for security, especially in defense and government. Learn more about zero trust and how it affects architecture and implementation, data security, and software supply chain security — next in this series.

Zero trust is the architecture that makes cyber resilience possible — it is part of a modern security framework and aligns with government and commercial cybersecurity strategy alike. Mercury Systems is a technology company delivering signal solutions, software applications, networking, storage, and secure processing in support of aerospace, defense and commercial critical infrastructure missions. Mercury’s RelianceOne™ hardens operationally deployed systems and boosts their cyber resilience to protect data and operations.