What is NFVI?
Network Functions Virtualization Infrastructure (NFVI) is the foundational layer that enables the virtualization of telecom services. It encompasses all the physical and virtual resources—compute, storage, networking, and the virtualization layer—required to host and run Virtualized Network Functions (VNFs) and Cloud-Native Network Functions (CNFs).
Instead of relying on dedicated, proprietary appliances, modern telecom environments use NFVI to host software-based network functions on standard servers. This transformation enhances agility, reduces costs, and allows operators to scale services more dynamically. However, it also introduces a broader attack surface that requires deep security awareness.
The Architecture of NFVI
NFVI consists of several key components working together to provide the virtual execution environment:
- The compute layer includes physical servers running virtual machines or containers that host the actual network functions.
- The storage layer offers persistent storage volumes that are shared across VNFs or tied to specific functions.
- The networking layer connects VNFs using virtual switches, physical interfaces, and SDN overlays.
- The virtualization layer (hypervisors like KVM, or container runtimes like Docker) abstracts and manages the hardware.
- Finally, orchestration and lifecycle management tools, often based on OpenStack or Kubernetes, are responsible for deploying and managing VNFs and their supporting resources.
Together, these layers form the platform on which modern telecom networks operate, especially within 4G and 5G core infrastructures.
Why NFVI Matters in Telecom Security
NFVI isn’t just an IT abstraction—it sits at the heart of mobile networks. A breach at the NFVI level can compromise every service built on top of it. If an attacker gains access to the NFVI stack, they can potentially control or observe multiple virtualized functions, disable core network services, manipulate orchestration logic, and bypass traditional network segmentation.
This makes NFVI one of the most strategically critical layers to secure. The security of subscriber databases, lawful interception systems, authentication servers, and even 5G slices may all depend on the integrity of the underlying NFVI.
Key Security Risks in NFVI
One of the most prominent risks in NFVI is the vulnerability of the hypervisor or container runtime. If these layers are compromised, an attacker can perform virtual machine (VM) escape attacks, breaking isolation between tenants or accessing the host operating system. In multitenant environments—such as those supporting network slicing—this can result in data leakage, privilege escalation, or service disruption.
The orchestration layer is another critical risk area. Misconfigured templates, poorly secured APIs, or privilege mismanagement in orchestration tools like OpenStack or Kubernetes can allow attackers to spin up unauthorized VNFs, inject malicious workloads, or tamper with running network functions.
Lack of east-west traffic visibility within NFVI is another concern. Traditional security tools often lack insight into internal communications between VNFs, making lateral movement easy to hide. Flow mirroring, packet manipulation, and data exfiltration can go undetected without proper inspection capabilities.
Another issue lies in shared hardware risks, where flaws like Spectre or Meltdown allow attackers to steal data across virtual machines running on the same physical CPU. In scenarios where infrastructure is shared between multiple tenants or slices, the consequences can be significant.
NFVI Attack Vectors in Practice
In a real-world attack scenario, an adversary might start by exploiting a vulnerability in a publicly exposed orchestration API. This access can then be used to deploy a rogue VNF designed to intercept signaling traffic. The attacker could then harvest subscriber data or redirect control messages. In another case, an unpatched hypervisor could allow an attacker to break out of a compromised VNF and tamper with other critical components—such as authentication servers or DNS resolvers—residing on the same infrastructure.
Even internal service discovery mechanisms used in Kubernetes clusters or OpenStack environments can be abused to map the virtual environment, escalate privileges, or execute remote commands.
Best Practices for Securing NFVI
Securing NFVI starts with hardening the virtualization layer. Hypervisors should be stripped of unnecessary services, regularly patched, and monitored for anomalies. Admin interfaces must be locked behind strong authentication and network segmentation.
Isolation is critical. Wherever possible, different VNFs or network slices should run on separate compute nodes, or use hardware-based isolation such as VT-d or AMD SEV. CPU pinning and memory separation can also help reduce resource leakage risks.
The orchestration layer must be treated as a high-value asset. Limit access to orchestration APIs through role-based access controls and API gateways. Only signed, validated images should be permitted into production. Secure the container registry or image repository with authentication and vulnerability scanning.
Security teams must implement deep traffic inspection across the NFVI fabric, especially for east-west flows between VNFs. Deploy virtual DPI probes, integrate logs into a telecom-aware SIEM, and implement network flow monitoring. Alerts should be generated when unauthorized service-to-service communication is detected.
Lastly, infrastructure integrity must be verifiable. Use hardware root of trust, secure boot, and attestation frameworks to ensure only verified workloads are running. Automate compliance checks for system configuration, kernel versions, and runtime permissions.
NFVI and 5G Network Slicing
In 5G networks, NFVI plays an essential role in supporting network slicing, where multiple isolated virtual networks coexist on shared infrastructure. If NFVI security is weak, it becomes possible for one slice to interfere with another—violating isolation, leaking sensitive data, or corrupting service-level agreements.
Operators must ensure strong slice isolation at the infrastructure level, not just in software policy. This includes isolated storage, compute affinity enforcement, and strict orchestration permissions. Monitoring must be granular enough to detect inter-slice violations and unauthorized access attempts.
Compliance and Standards
Several industry standards offer guidance on NFVI security. The ETSI NFV Security (NFV-SEC) group provides a detailed threat landscape and architectural safeguards for NFV and NFVI. The GSMA FS.36 document outlines best practices for NFV infrastructure security, particularly in multi-vendor telecom environments.
Additional standards such as NIST SP 800-190 (for container security) and 3GPP TS 33.501 (for 5G security architecture) provide relevant guidance, especially in cloud-native deployments. Compliance with these frameworks helps align operational security with industry expectations and regulatory requirements.
Conclusion
NFVI is the unseen backbone of today’s telecom networks. It enables flexibility, scalability, and innovation—but it also brings complexity and a high-stakes threat surface. As mobile networks continue to virtualize and evolve, securing NFVI is not just an IT hygiene task—it’s a critical security priority.
From hypervisor exploits and multitenancy risks to orchestration layer abuse and hardware-level threats, telecom operators must treat NFVI with the same seriousness as traditional telecom core equipment. Only by doing so can they ensure a secure foundation for 4G, 5G, and the networks beyond.
