Can ransomware really encrypt a hypervisor?

Yes. Several active ransomware families ship purpose-built binaries for common hypervisor operating systems. A single compromised host can take out every VM it runs.

Does our cloud provider protect us from ransomware?

The provider secures the underlying platform. You remain responsible for tenant configuration, admin accounts, MFA, patching of guest operating systems and user access. That is the shared responsibility model.

Is our supplier's Cyber Essentials certificate enough?

No. It covers the supplier's scope. Your organisation still needs its own certification and its own controls over user devices, cloud apps and data.

How does CE Plus test a virtualised environment?

By sampling management planes, host pools, gold images and end-user devices. See our CE Plus in cloud and virtualised environments article.

Ransomware, VDI and Virtual Machines: Why Hosted Does Not Mean Protected

Why virtual environments are attractive targets

Encrypting a single hypervisor can knock out every virtual machine running on it. Compromising a VDI management plane can lock out every user at once. That force multiplier is exactly why ransomware operators now build tooling specifically for virtualised estates.

What is actually in scope

Cloud and tenant management consoles (AWS, Azure, GCP, M365, VDI control planes).
Hypervisors and their management networks, where you operate them.
Server operating systems inside VMs.
Administrator endpoints used to reach any of the above.
User devices and thin clients that access the environment.

For the scope specifics, see what is in scope for VDI, are hypervisors in scope, and CE Plus in cloud and virtualised environments.

Where ransomware typically breaks in

Cloud or VDI admin accounts without MFA.
Exposed management endpoints reachable from the internet.
Compromised administrator laptops used as a jump host.
Unpatched hypervisor management software.
Stolen credentials for a supplier or MSP with standing tenant access.

The dangerous assumption to retire

"Our hosted desktop provider is Cyber Essentials certified, so we are covered." That is not how certification works. A supplier's certificate covers the supplier's scoped environment. Your users, devices, cloud apps and data are still your scope. See why supplier certificates do not extend to customers.

Practical checks for virtualised estates

Every cloud and VDI admin account has phishing-resistant MFA, including break-glass accounts.
Management planes are not reachable from the open internet without conditional access.
Hypervisor and control-plane software is patched to a documented cadence.
Administrator endpoints are hardened, patched and monitored to the same standard as the servers they manage.
Supplier access is time-bound, logged and revocable.
Backups of VMs are immutable and tested by restore, not by report.