What Is Network Access Control (NAC) in Cyber Security?
Network Access Control (NAC) is a foundational cyber security technology designed to ensure that only authorized users, devices, and systems can access network resources. For many organizations, particularly financial institutions, NAC security solutions have become an essential component of regulatory compliance and access control strategies.
Over the past decade, nearly every financial institution we have spoken with has implemented some form of NAC cyber security solution. While improving security is an important objective, many CISOs cite regulatory requirements as the primary driver for adoption.
Regulatory bodies worldwide increasingly require organizations to maintain asset inventories, control network access, and strengthen identity management practices. As a result, Network Access Control (NAC) solutions became the natural choice for enforcing access policies and demonstrating compliance.
However, today’s threat landscape has evolved significantly. Modern networks contain unmanaged devices, IoT systems, operational technology (OT), remote users, and third-party assets that traditional NAC implementations were not originally designed to address. As regulators place greater emphasis on device identity, supply chain security, and Zero Trust architectures, organizations must look beyond compliance and focus on reducing actual cyber risk.
Why Traditional NAC Security Solutions Are No Longer Enough
Traditional NAC cyber security solutions were designed for a different era. Like a general preparing for the last war, many NAC platforms focus on challenges that were relevant when most assets were managed endpoints operating within clearly defined network boundaries.
Today, organizations face a far more complex environment. Cloud adoption, hybrid work models (WFH), Bring Your Own Device (BYOD) programs, expanding supply chains, IoT deployments, and increasingly sophisticated hardware-based attacks have created new security challenges that traditional NAC security solutions often struggle to address.
Most NAC implementations rely heavily on information reported by the device itself, such as MAC addresses, certificates, or authentication credentials. While useful, these identifiers can be manipulated, spoofed, or misrepresented by attackers seeking unauthorized access.
As a result, organizations need more than traditional Network Access Control (NAC). They need confidence that devices are truly what they claim to be. Modern NAC security strategies should combine access control with independent device identity validation, enabling organizations to detect unauthorized, unmanaged, or spoofed devices before they can gain access to sensitive systems and data.
Security leaders must prepare for emerging regulatory requirements and evolving threats by adopting solutions that support Zero Trust principles and establish trusted device identities across the network.
Challenges with Network Access Control (NAC)
Implementation Challenges
Implementing a NAC cyber security system can be complex and challenging, particularly for large and distributed financial institutions. Network Access Control (NAC) implementation projects are well known for taking longer than originally planned, sometimes years, and costing significantly more than originally budgeted.
Network Access Control (NAC) implementations require specialized skill sets that make identifying the suitable team an additional challenge. As a result, many Network Access Control (NAC) implementation projects don’t make it to original planned outcome. Thus cover only a portion of the organization’s network infrastructure.
Ongoing Maintenance and Administrative Burden
On-going management and maintenance of Network Access Control (NAC) systems is a known operational and administrative burden on the security IT team. It requires ongoing manual support to address and adjust NAC configuration to meet the organization changes.
Scalability Issues in Growing Networks
As financial institutions grow, the number of devices and users connecting to the network increases while network boundaries also change. For example, additional branches or types of devices are added to or removed from the network. Each change requires significant internal resources to test and update and extend the NAC. At the pace of changes in today’s world, the NAC is consistently behind, causing gaps in protection.
Cost Considerations for Financial Institutions
Due to the complexity and support that NACs require to work effectively, the costs, especially specialized labor, jump dramatically and create a barrier to acquisition and/or full implementation for smaller and medium-sized institutions. As a result of that, most projects fall short to complete full network infrastructure coverage.
Dealing with False Positives
NAC systems are known for producing false positives, disrupting workflow by blocking legitimate users and devices. This is frustrating for any financial institution implementing a NAC and leads to unnecessary loss of productivity. False positives can emerge from a multitude of reasons, e.g., misconfiguration, outdated software, hybrid work environment, and many more. As a result, most NAC systems are not used in enforcement mode. But rather left for visibility only.
Visibility Issues with IoT and OT Devices
Most NAC profiling techniques do not provide sufficient visibility or context for IoT and OT devices. This creates a significant gap in NAC cyber security because the diversity and complexity of these assets make them difficult to identify and classify accurately.
Many NAC security solutions rely on simple identifiers such as MAC addresses, IP addresses, or vendor information to profile these devices. As a result, organizations often lack the ability to continuously track these assets or validate their true identity on the network.
Effective NAC cyber security requires more than visibility. Organizations need confidence that connected devices are truly what they claim to be. By validating device identity rather than relying solely on self-reported information, security teams can reduce the risk of spoofing, unauthorized hardware, and unmanaged assets gaining network access.
Security Bypass Risks
Traditional NAC security solutions focus on granting or denying access based on device-reported attributes and authentication status. However, attackers can bypass these controls through device spoofing, compromised credentials, rogue hardware, or tools designed to impersonate trusted assets.
A Zero Trust Hardware Access approach complements NAC by independently validating device identity. This enables organizations to identify unmanaged, unauthorized, or spoofed devices before they are trusted on the network, reducing the risk of successful bypass attempts.
Compliance and Regulatory Challenges
As discussed, financial institutions are subject to many regulatory requirements and industry standards, (e.g. Official PCI Security Standards Council Site) and governmental privacy laws around the world. Ensuring compliance with all these regulations is challenging especially as they become more stringent in their asset inventory and access controls, requiring timely documented updates of all assets an organization owns. NACs do not meet today’s challenges in creating asset inventories and documentation, leaving regulations unfulfilled.
Enhancing Your NAC Cyber Security
How do we improve all these issues related to NACs? What can be done to address NACs’ original implementation goals?
The answer differs depending on whether an organization has already implemented a Network Access Control (NAC) to its fullest coverage.
To improve your Network Access Control (NAC) coverage, your best and most cost-effective approach is to add an additional defense layer that provides completeness and truth of assets connected to your network infrastructure. The data from this additional defense layer needs to include all assets. Regardless of if they are actively communicating, IoT/OT/IT or even peripherals, 802.1x compliant, or any other new category to find. The data needs to be fresh with near real-time updates and scale across your entire ecosystem. Should not impact production traffic, causing contention to the network infrastructure, or requiring additional hardware overhead to compensate.
NAC Journey: Implementation and Optimization
If you are early in your NAC cyber security journey or would like to complement your current coverage with an additional layer, there are a number of approaches you can take to either replacing the Network Access Control (NAC). Which will leave you in a better global security posture without the headaches or replace portions of the Network Access Control (NAC) implementation. They include implementing Zero Trust Network Access, and utilizing what Gartner refers to as “lightweight NAC”.
In any of these approaches, complete visibility and asset identity truth again become critical to network infrastructure security controls. At the time of connection, security teams must first discover devices. Correctly identify them, assess their potential risk and outcome to determine the suitability of access, and block them if necessary.
If you need help along your journey of improving your Network Access Control (NAC) or moving beyond it, Sepio is here.
Talk to an expert. It will help you understand how to use Sepio’s patented technology to gain control of your asset risks. Sepio is purpose-built to solve these issues plaguing security teams by allowing for a complete, trafficless global solution that gives you ultimate visibility, true asset identity, and risk mitigation.
