Hypervisor Escape Attack Explained: What It Is and How It Works

[johny899]

Have you ever wondered what occurs when the VM (virtual machine) is compromised and the hacker or intruder gains access to the main machine? This is known as a hypervisor escape attack, and it is important to understand if you are using VMs on platforms like VMware, Hyper-V, or KVM.

How does a Hypervisor Escape function?​

A hypervisor is a piece of software used to allow a multiple amount of VMs to run on a single computer. Each VM should function independently and not be able to affect any other VMs or the computer running the hypervisor. When a hacker conducts a hypervisor escape attack, these precautions collapse. It is like a guest evading their hotel room to enter other parts of the hotel or even the front desk.

In order to make this escape, the hacker uses some combination of software bugs, vulnerabilities, or misconfigurations to gain access from the VM to the main computer. Once on the main computer, the hacker is able to discover and see other VMs, exfiltrate data, and even take control of the entire system.

Where It Can Occur​

You may ask, "Does this happen frequently?" No, but it could be unsafe. It may occur when:

• There are vulnerabilities in the hypervisor (like VMware ESXi or Hyper-V).
• The VMs have excessive privileges, which gives the attacker a way in.
• Hypervisors permit sharing memory or storage among VMs, allowing the attacker to escape.

It's similar to an unlocked window; any smart person could get in.

How To Avoid It​

You can avoid it by:

• Applying updates more often to hypervisors to fix bugs.
• Keeping VMs separate; don't share memory, storage, or network unless you have to.
• Monitoring activity of VMs with tools like Nagios or Grafana.

In my personal experience, keeping VMs isolated and updating as often as possible prevents 90% of any issues. One time I misconfigured something that almost allowed me to access the host computer, but updates and isolation blocked it.

Conclusion​

Hypervisor escape attacks can sound frightening. However, awareness is generally a good thing. Always ensure software is up to date, logically separate VMs, and look for any abnormalities in the activities of the VMs.

It is important to remember: the VM is only as secure as the hypervisor is secure; if there are security vulnerabilities in the hypervisor, the entire server is exposed to risk from those vulnerabilities.

Have you ever considered how embedded a hacker can go inside your server? Following these mitigating controls for hypervisor escape attacks will ensure that your VMs are secure.