Impact
Users with host file system access on a node and the privileges to run as group ID 1000 can gain access to the per node API of Cilium via Unix domain socket on the host where Cilium is running. If a malicious user is able to gain unprivileged access to a user corresponding to this group, then they can leverage this access to compromise the integrity as well as system availability on that host. Operating Systems that have unprivileged users not belonging the group ID 1000 are not affected by this vulnerability.
Best practices for managing the secure deployment of Kubernetes clusters will typically limit the ability for a malicious user to deploy pods with access to this group or to access the host filesystem, and limit user access to the nodes for users belonging to this group. These best practices include (but are not limited to) enforcing Admission Control policies to limit the configuration of Kubernetes Pod hostPath and SecurityContext fields.
Patches
Cilium versions >=1.9.16, >=1.10.11, >=1.11.5 mitigate this issue by setting the default group to 0 (root).
Workarounds
Prevent Cilium from running with group 1000 by modifying Cilium's DaemonSet to run with the following command:
containers:
- name: cilium-agent
args:
- -c
- "groupdel cilium && cilium-agent --config-dir=/tmp/cilium/config-map"
command:
- bashinstead of
containers:
- name: cilium-agent
args:
- --config-dir=/tmp/cilium/config-map
command:
- cilium-agentAcknowledgements
The Cilium community has worked together with members of Isovalent and Form 3 to prepare these mitigations. Special thanks to Daniel Iziourov and Daniel Teixeira for their cooperation.
For more information
If you have any questions or comments about this advisory:
References
Impact
Users with host file system access on a node and the privileges to run as group ID 1000 can gain access to the per node API of Cilium via Unix domain socket on the host where Cilium is running. If a malicious user is able to gain unprivileged access to a user corresponding to this group, then they can leverage this access to compromise the integrity as well as system availability on that host. Operating Systems that have unprivileged users not belonging the group ID 1000 are not affected by this vulnerability.
Best practices for managing the secure deployment of Kubernetes clusters will typically limit the ability for a malicious user to deploy pods with access to this group or to access the host filesystem, and limit user access to the nodes for users belonging to this group. These best practices include (but are not limited to) enforcing Admission Control policies to limit the configuration of Kubernetes Pod hostPath and SecurityContext fields.
Patches
Cilium versions >=1.9.16, >=1.10.11, >=1.11.5 mitigate this issue by setting the default group to 0 (root).
Workarounds
Prevent Cilium from running with group 1000 by modifying Cilium's DaemonSet to run with the following command:
instead of
Acknowledgements
The Cilium community has worked together with members of Isovalent and Form 3 to prepare these mitigations. Special thanks to Daniel Iziourov and Daniel Teixeira for their cooperation.
For more information
If you have any questions or comments about this advisory:
References