Are your virtualized environments secure?

Virtualization has become the backbone of modern enterprise IT, underpinning everything from cloud deployments to disaster recovery strategies.

By abstracting workloads from physical hardware, virtual machines (VMs) deliver undeniable benefits, such as flexibility, cost efficiency, and scalability.

Yet this very abstraction introduces unique security challenges that differ fundamentally from those of traditional bare metal systems. Protecting virtual machines within an enterprise environment can be a difficult task, as cybersecurity teams and IT workers have to ensure nothing is overlooked in the deployment process.

Risks unique to virtualization that enterprises face

One of the biggest risks in virtualized environments lies not within the guest VMs themselves but in the hosts that power them. “Unlike a physical server running Windows, Linux, or even Mac, there are very few, if any, endpoint protection/EDR solutions for the VM host itself,” explains Paddy Harrington, senior analyst at Forrester Research. “For most environments, the best they can do is harden the host deployment through configuration and restricted administrative access, and utilize network-based solutions to monitor for threats targeting the host.”

The problem extends into the VMs, too. Many organizations opt not to install local security agents on guest servers to conserve resources or because of the perceived lack of user activity.

Harrington notes that test environments are particularly problematic: “Virtualization has always had a use case with testing; desktops, servers, apps, etc., spinning up virtual workloads to test apps, configs, conflicts, and so forth is easiest done in the virtual space because once the tests are done, you delete the VM and you’re back to where you started.

“The issue is that test environments are rarely built with security in mind, and sometimes, the test servers are left running unprotected. If a malicious actor is looking for a place to take up residence in the short term, they will target test environments as they go looking for more lucrative soft targets within the infrastructure.”

How configuration errors can expose VMs to attacks

One of the most pressing risks with VMs is that of configuration errors, which can introduce vulnerabilities into otherwise secure environments.

Jim McGann, CMO at Index Engines, tells ITPro that this is not a risk that should be overlooked:

"Configuration errors in virtualized environments are particularly dangerous because they often involve foundational security controls.

“Properly managing multiple VMs is essential to avoid misconfigurations, and unauthorized access to virtual infrastructure poses a significant threat. Common misconfigurations include inadequate network segmentation between VMs, overprivileged service accounts, and weak access controls to the hypervisor management layer.”

These issues are magnified by the scale at which virtualization operates in enterprises, McGann explains, with even a single error in an automation script carrying the potential to spread vulnerabilities across tens of thousands of VM instances.

Endpoint security in virtual environments

In many respects, endpoint detection and response (EDR) and endpoint protection platforms (EPP) operate within VMs the same way they do on physical machines. But virtualization does bring performance considerations. Harrington notes that “the biggest issue is resource utilization.

“The biggest issue is resource utilization,” Harrington notes. “Some vendors can keep the resources low by offloading any sort of scans that could spike resources to a secondary server within the infrastructure. This is helpful for VDI environments, especially where enterprises will have thousands of VMs spread out across many hosts.”

For enterprises embracing virtualization, one of the most frequent errors is treating VM security as an afterthought. McGann says organizations can overlook security processes in the rush to deploy virtualized infrastructure, sacrificing defense for operational efficiency.

VM sprawl is another problematic issue. Since VMs are so easy to deploy, IT teams often lose visibility into what’s running, leading to unmanaged shadow workloads. Backup and recovery planning can also be neglected, with traditional backup approaches failing to account for the interdependencies and rapid change rates of VM environments.

Virtualization features can be turned into attack vectors

Features inherent to virtualization such as snapshots, cloning, and live migration, can also open doors for attackers.

Roy Charman, CTO infrastructure platforms at Espria, warns that in the hands of hackers, snapshots can act as “time machines” to resurrect patched vulnerabilities. “If attackers get control, they can roll back to an old, vulnerable state or quietly clone a VM and walk off with your data,” Charman says. “Live migration is another vector; if it’s not encrypted or segmented, attackers can sniff traffic and capture entire workloads as they’re being moved.”

McGann tells ITPro that these operational features create unique challenges: “Snapshots can preserve malware in a dormant state that evades detection, then be restored later to reactivate compromises.

“Attackers can also use cloning to rapidly propagate their presence across multiple VMs, weaponizing the very efficiency features that make virtualization attractive. Live migration presents particularly sophisticated opportunities for attackers. During migration, there are brief windows where security controls may be inconsistent between source and destination hosts. Advanced persistent threat actors have learned to time their activities around these operational windows."

The dangers of VM sprawl and shadow VMs

Unchecked VM sprawl directly increases the attack surface. Unlike physical servers, which require procurement and rack space, VMs can be created instantly by anyone with access. Shadow VMs, unmanaged workloads running outside of IT’s visibility, pose an especially high risk. “They can represent unknown attack vectors that security teams can’t defend against because they may not know they exist,” said McGann.

Charman likens them to “forgotten laptops lying around your office, all still plugged into the network”, adding: “Shadow VMs often come from developers or admins spinning up test workloads and never cleaning them up. Each of those is another potential attack path.” He stressed that enterprises need effective tooling.

“The only real way to get control is through tooling,” he says. “Microsoft’s Hyper-V integrates nicely with System Center and Azure for inventory. Without that, you’re relying on people’s memory, which is a recipe for trouble.”

New technologies are starting to strengthen the security foundations of virtualization. Confidential computing and hardware-assisted isolation aim to address architectural weaknesses by reducing the reliance on hypervisors and software-only controls and Harrington points out that encryption and isolation “provide a more secure platform to start the environment with, although they don’t remove the need for best practices such as least-privileged access for VM admins and secure practices while setting up the VMs”.

McGann highlights the broader impact, explaining that these new technologies get to the heart of the fundamental weaknesses in the architecture of virtualization approaches up to now.

“Confidential computing changes the game by ensuring that even the hypervisor or cloud provider cannot access VM memory and processing in plaintext,” he says. “This reduces the impact of successful hypervisor compromises. Hardware-assisted isolation technologies provide stronger boundaries between VMs than software-only approaches.”

Virtualization delivers agility, scalability, and cost savings and also reshapes the threat landscape. Misconfigurations, VM sprawl, and overlooked test environments all create opportunities for attackers, while powerful features like snapshots and live migration can be weaponized if not secured properly. To stay ahead, enterprises must treat VM security as a core design principle rather than an afterthought. With disciplined governance, careful configuration, and emerging safeguards such as confidential computing and hardware-assisted isolation, organizations can harness the full value of virtualization without leaving themselves exposed.