Описание
On a compromised node, the virt-handler service account can be used to modify all node specs
Impact
If a malicious user has taken over a Kubernetes node where virt-handler (the KubeVirt node-daemon) is running, the virt-handler service account can be used to modify all node specs.
This can be misused to lure-in system-level-privileged components (which can for instance read all secrets on the cluster, or can exec into pods on other nodes). This way a compromised node can be used to elevate privileges beyond the node until potentially having full privileged access to the whole cluster.
The simplest way to exploit this, once a user could compromise a specific node, is to set with the virt-handler service account all other nodes to unschedulable and simply wait until system-critical components with high privileges appear on its node.
Since this requires a node to be compromised first, the severity of this finding is considered Medium.
Patches
Not yet available.
Workarounds
Gatekeeper users can add a webhook which will block the virt-handler service account to modify the spec of a node.
An example policy, preventing virt-handler from changing the node spec may look like this:
and applying this template to node modifications.
Credits
Special thanks to the discoverers of this issue:
Nanzi Yang (nzyang@stu.xidian.edu.cn) Xin Guo (guox@stu.xidian.edu.cn) Jietao Xiao (jietaoXiao@stu.xidian.edu.cn) Wenbo Shen (shenwenbo@zju.edu.cn) Jinku Li (jkli@xidian.edu.cn)
References
Пакеты
kubevirt.io/kubevirt
<= 0.59.0
Отсутствует
Связанные уязвимости
KubeVirt is a virtual machine management add-on for Kubernetes. In versions 0.59.0 and prior, if a malicious user has taken over a Kubernetes node where virt-handler (the KubeVirt node-daemon) is running, the virt-handler service account can be used to modify all node specs. This can be misused to lure-in system-level-privileged components which can, for instance, read all secrets on the cluster, or can exec into pods on other nodes. This way, a compromised node can be used to elevate privileges beyond the node until potentially having full privileged access to the whole cluster. The simplest way to exploit this, once a user could compromise a specific node, is to set with the virt-handler service account all other nodes to unschedulable and simply wait until system-critical components with high privileges appear on its node. No patches are available as of time of publication. As a workaround, gatekeeper users can add a webhook which will block the `virt-handler` service account to ...
KubeVirt is a virtual machine management add-on for Kubernetes. In versions 0.59.0 and prior, if a malicious user has taken over a Kubernetes node where virt-handler (the KubeVirt node-daemon) is running, the virt-handler service account can be used to modify all node specs. This can be misused to lure-in system-level-privileged components which can, for instance, read all secrets on the cluster, or can exec into pods on other nodes. This way, a compromised node can be used to elevate privileges beyond the node until potentially having full privileged access to the whole cluster. The simplest way to exploit this, once a user could compromise a specific node, is to set with the virt-handler service account all other nodes to unschedulable and simply wait until system-critical components with high privileges appear on its node. No patches are available as of time of publication. As a workaround, gatekeeper users can add a webhook which will block the `virt-handler` service account to mod
Security update for kubevirt, virt-api-container, virt-controller-container, virt-handler-container, virt-launcher-container, virt-libguestfs-tools-container, virt-operator-container