What is VM Escape?

How to Allow a Program Through Firewall: A Step-by-Step Guide

What is VM Escape?

Are you by any chance a manager in shared computing environments for multiple customers, and you get worried about one of your customers accessing virtual machines of the other customers? I’m sure you would love to protect against virtual machine escape attacks. So, what is VM escape?

Virtual machine escape in computer security is whereby a process of a program bursts out of the virtual machine on which it is operating and interacting with the system of the host. VM is a system that is totally isolated guest running system installation within a typical host operating system.

In the year 2008, core security technologies discovered a vulnerability CVE-2008-093 in virtual machine ware. It made virtual machine escape possible on a virtual machine ware workstation 6.0.2 and also 5.5.4. immunity Inc developed an amply working exploit that they labeled cloudburst. They represented the cloudburst in the USA in 2009. 

Now let us learn more about the VM escape in detail.

Virtual Machine Escape

The exploit can allow the attacker to access the host operating system and the other virtual machines operating on that particular host. Virtual machine escape is regarded as the most serious threat to VM security, although there have been no incidents reported in the wild.

Virtual machines are made in such a way that they operate in self-contained and isolated environments inside the host. Thus, every virtual machine ought to be a  separate system, in effect, apart from the host operating system and all other virtual machines operating on the same device.

The hypervisor acts as an intermediary between the virtual machines and the host operating system. It also works to control the host processor and distributes resources as needed to each guest operating system.

The Risk

If the attacker can adjust the virtual machines, they are likely to have control over all the guests because the guests are solely subsets of the program itself. 

In addition, most virtual machines operate with very high privileges on the host since a virtual machine requires a broad scope of access to the host’s hardware in order to map the real hardware into a virtualized hardware for the guests. Hence compromising the VM means that the guests are goners, and the host is probably lost.

How to Minimize Vulnerability to Virtual Machines Escape?

To reduce the vulnerability, I would recommend the following:

  • Keep the VM software patched.
  • Only install the resource-sharing features that you need
  • Keep software installation to a minimum level since each program has its own vulnerabilities.

The VM escape attacks aim at the vulnerabilities in the hypervisor that supports a virtualized environment. To strongly control to protect hypervisors against VM attacks is just to keep them patched. Port security and network firewalls are network security controls that appear outside the virtualized environment and would not be necessary in this case. Input validation is another application security control.


The hypervisor, also known as virtual machine monitors, is a type of software that makes and runs virtual machines. It permits one host computer to support many guests’ virtual machines by virtually sharing its resources like memory and processing.

Hypervisors enable more usage of a system’s available resources and offer greater IT mobility because the guest virtual machines do not depend on the host hardware. It means that they can be moved easily between separate servers. This is because multiple virtual machines can run off one physical server with a hypervisor. Hypervisors minimize maintenance needs, space, and energy.

How do Hypervisors work?

They support the creation and management of VMs by withdrawing a computer’s software from its hardware. They enable virtualization by translating requests between the virtual and the physical resources. 

Bare metal hypervisors at times are embedded into the firmware at the same level as the motherboard basic input or output system to make it possible for the operating system on a computer to access and use virtualization software.

Advantages of Hypervisors

It is beneficial to use a hypervisor that hosts many virtual machines

  1. Speed

Unlike bare-metal servers, hypervisors permit the instant creation of virtual machines. This makes it easy for resources to be provided as required for dynamic workloads.

  1. Portability

Hypervisors permit multiple running systems to stay on the same host machine. Since the VMs that the hypervisor operates are separate from the physical machine, they are portable.

  1. Efficiency 

The hypervisors that operate several virtual machines on one host computer resource also permit more efficient physical server utilization. This makes it more cost and energy-efficient to manage multiple virtual machines on one computer than to run various underutilized physical machines for that same task.

Virtualization Security

Hypervisors offer isolation between guest OS. They also manage their access to virtualized hardware. This particular isolation is a great concern for virtual machine security simply because it is a great technique to prevent the guest OS  from attacks which would likely infect the entire guests’ OS. 

This might be a benefit to the security defenders. However, it could also be of advantage to the attackers and by causing tsunami exploitation for the whole system at large.

If by any chance a sophisticated attacker dominates the hypervisor, at this point, the attacker has total control over the resources within the hypervisor. It means that the attacker exploited ring 0 successfully on the host. 

The possibility of this attack is complex since the hypervisor has less code and operates on the most elite level of security. This particular type of attack is critical to a company that has a cloud architecture. 


Typically, it is easy and very cheap for an attacker to dominate your computer. However, suppose you isolate the parts of your computer that can get attacked within the virtual machines. In that case, you will automatically make taking over your computer more difficult, expensive, and probably not worth it.

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