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Kernel-based Virtual Machine

(also KVM)

Kernel-based Virtual Machine definition

Kernel-based Virtual Machine is an open-source virtualization technology built into the Linux kernel. It allows the kernel to function as a hypervisor, enabling a host machine to run multiple isolated virtual machines (VMs).

KVM leverages hardware virtualization extensions, such as Intel VT or AMD-V, to provide a near-native execution environment for VMs, delivering high performance and efficiency.

See also: hypervisor

Dangers associated with KVM

  • Vulnerabilities. KVM is tightly integrated with the Linux kernel, so its vulnerabilities can affect the security of the KVM virtualization environment. An attacker could use a Linux kernel vulnerability to escape from a guest VM to the host or other VMs.
  • Misconfiguration. Incorrect configuration of KVM, its network settings, or storage can introduce security risks. For example, if VMs are not properly isolated on the network, it might allow for unintended access between VMs.
  • Resource starvation. VMs share physical resources. An aggressively consuming VM or misconfigured resource allocation can starve other VMs of critical resources, affecting their performance or causing downtime.
  • Guest VM vulnerabilities. A compromised guest VM could be a launching point for attacks on other VMs or the host.
  • Nested virtualization risks. Running virtual machines inside other virtual machines (nested virtualization) introduces more complexity and potential attack vectors.
  • Snapshot and migration risks. VM snapshots can contain sensitive data. If not managed or secured properly, they can pose a risk. Similarly, the migration of VMs between hosts can be intercepted or tampered with if not properly secured.
  • Dependence. KVM relies on hardware virtualization extensions (Intel VT-x and AMD-V). If the hardware doesn't support these features, or if they are disabled, KVM cannot function.
  • Complexity. Integrating various tools and components (like QEMU, libvirt, etc.) adds layers of complexity, which often is a source of errors or misconfigurations.