The Ultimate Guide to Hypervisors: Definitions, Types, and Security

As the world become increasingly digitized through the use of computers, cloud services, and other virtual tools, organizations and individuals have become more vulnerable to data breaches. 

In this blog, you'll learn about hypervisors and why their security is critical to preserving data integrity and reducing cyberattacks. 

What is a hypervisor? 

A hypervisor, which is also called a virtual machine monitor (VMM), is a software that creates and runs virtual machines (VMs). 

A virtual machine is, in essence, a virtual computer, but with one difference: it uses software instead of hardware to run programs and deploy applications.

Various "guest" virtual machines run on a "host" machine--i.e. the computer. Each virtual machine has its own operating system (OS) and functions separately from the other virtual machines. 

This introduces a high level of efficiency and flexibility, while providing greater security coverage for your operating system. 

A hypervisor allows the computer to support multiple virtual machines by sharing the computer's resources, such as memory and processing. 

How does a hypervisor work? 

Hypervisors assist in creating and managing virtual machines by extracting a computer's software from its hardware; they make virtualization possible by translating requests between physical and virtual resources. 

Hypervisors are sometimes embedded into firmware at the BIOS level to enable the operating system on a computer to access and use virtualization software. (More on the different types of hypervisors later.) 

Benefits of a hypervisor

There are four main benefits of a hypervisor: speed, efficiency, flexibility, and portability. 

1. Speed: A hypervisor allows virtual machines to be created instantly, making it easier to distribute the necessary resources for workloads. 
2. Efficiency: A hypervisor can run several virtual machines on one computer's resources as opposed to running multiple computers for the same task, saving time, energy, and money. 
3. Flexibility: Certain types of hypervisors allow operating systems and their associated applications to run on different types of hardware because the hypervisor separates the operating system from the underlying hardware. This frees the software from relying on hardware devices or drivers. 
4. Portability: A hypervisor allows multiple operating systems to reside on the same host machine. Since virtual machines that the hypervisor runs are independent from a physical machine, they are portable. IT teams can move workloads and allocate networking, memory, storage, and processing resources across multiple severs as needed. If an application needs more processing power, the hypervisor allows it to access additional virtual machines. 

Types of hypervisors

There are two types of hypervisors: Type 1 ("bare-metal") and Type 2 ("hosted"). 

Type 1 (bare-metal) 

A bare-metal hypervisor acts like a lightweight operating system and runs directly on the host machine's hardware. This is the most commonly deployed type of hypervisor. 

These types of hypervisors are installed directly on the hardware, and they are located in between the hardware and the operating system.

As mentioned previously, sometimes bare-metal hypervisors are embedded into firmware at the BIOS level to enable the operating system on a computer to access and use virtualization software. 

Because bare-metal hypervisors are separate from the attack-prone operating systems, they are very secure and, as as result, perform better and more efficiently than other types of hypervisors. 

A separate management machine, however, is often needed to administer the different virtual machines and control the host hardware. 

Type 2 (hosted)

A hosted hypervisor runs on top of the operating system of the host machine. 

Although these types of hypervisors run within the operating system, additional and different operating systems can also be installed on top of the hypervisor. 

However, communication between the hypervisor and the hardware must pass through an extra layer of the operating system, potentially leading to higher levels of latency. 

Additionally, since hosted hypervisors need to access computing, memory, and networking resources via the operating system, a hacker compromising the host OS means that they could manipulate any guest OS running within the hypervisor. 

How does a hypervisor differ from a container? 

A container is a standard unit of software that packages up code and all its dependencies so that an application runs quickly and reliably from one computing environment to another. 

Since containers are more portable and lightweight than virtual machines, they are often used for fast and flexible application movement and development. 

There are, however, some differences between hypervisors and containers:

A hypervisor: 

1. Allows an operating system to run independently of underlying hardware through the use of virtual machines
2. Shares virtual computing, storage, and memory resources
3. Can run multiple operating systems on top of a computer's hardware or installed on top of one isolated operating system

A container: 

1. Allows applications to run independently of an operating system
2. Can run on any operating system, only needing a container engine to turn on
3. Is more portable since an application has all it needs to run

Why is hypervisor security important?

Though hypervisors help to increase efficiency, their capabilities open the door to security risks. 

If a hacker gain access to a hypervisor that supports multiple virtual machines, they have access to all the virtual machines and their respective data, compromising security and performance.  

The same applies to hackers who gain access to the host operating system of a hosted hypervisor. 

How to secure your hypervisor 

Hypervisor security measures will help to prevent cyberattacks during development, implementation, provisioning, and management. 

There are five primary methods used to ensure hypervisor security: 

1. Monitoring and network security tools allow administrators to monitor their virtual environments and screen out strange behavior early on. 
2. Minimizing potential attack surfaces makes access to a virtual system more difficult by decreasing attack points. 
   1. For example, many hypervisors have additive features which may not be used that will increase the attack surface of a virtual machine. To decrease attack surface, administrators should disable unnecessary services and disable used hardware from host systems, allowing only services that are needed for a successful operation. 
3. Setting restrictions on who can have remote and console access limits who can control the settings of the hypervisor and prevent unauthorized users from changing or accessing information. 
4. Installing patches and updates to the hypervisor as the vendor releases them as updates may contain security patches (software that corrects errors in code) or additional security features. 
5. Blocking access to the physical servers is effective, as physical access is a common and easy way for hackers to access hypervisors. 
6. Multi-factor authentication: This means that multiple methods are used to identify users, combining something they know, something they own, and/or a physical characteristic. Read more about multi-factor authentication here. 

Hypervisors and Trenton Systems

In the face of increasingly sophisticated cyberattacks, it is imperative that security measures and technologies are developed and implemented to guard critical data at the highest level and thwart unauthorized access. 

At Trenton, we are committed to complete data protection across the hardware, firmware, and software layer stack to guard sensitive information and ensure optimal performance. 

Want to learn more? Get in touch with our team of experts to craft a customized, USA-made solution that enables you to achieve optimal performance across all domains of the modern battlespace, no matter where the mission leads.