Описание
Privilege escalation in project role template binding (PRTB) and -promoted roles
Impact
An issue was discovered in Rancher versions from 2.5.0 up to and including 2.5.16 and from 2.6.0 up to and including 2.6.9, where an authorization logic flaw allows privilege escalation via project role template binding (PRTB) and -promoted roles. This issue is not present in Rancher 2.7 releases.
Note: Consult Rancher documentation for more information about cluster and project roles and KB 000020097 for information about -promoted roles.
This privilege escalation is possible for users with access to the escalate verb on PRTBs (projectroletemplatebindings.management.cattle.io), including users with * verbs on PRTBs (see notes below for more information). These users can escalate permissions for any -promoted resource (see the table below for a full enumeration) in any cluster where they have a PRTB granting such permissions in at least one project in the cluster.
On a default Rancher setup, only the following roles have such permissions:
- Project Owner
- Manage Project Members
These roles have permissions to affect the following resources:
| Resource | API Group | Affected Rancher version |
|---|---|---|
| navlinks | ui.cattle.io | 2.6 |
| nodes | "" | 2.6 |
| persistentvolumes | "" | 2.5, 2.6 |
| persistentvolumes | core | 2.5, 2.6 |
| storageclasses | storage.k8s.io | 2.5, 2.6 |
| apiservices | apiregistration.k8s.io | 2.5, 2.6 |
| clusterrepos | catalog.cattle.io | 2.5, 2.6 |
clusters (local only) | management.cattle.io | 2.5, 2.6 |
Notes:
- During the calculation of the CVSS score,
privileges requiredwas considered ashighbecause, by default,standard useranduser-baseusers in Rancher do not havecreate,patchandupdatepermissions onroletemplates. - If a role template with access to those objects was already created by another user in the cluster, then this issue can be exploited by users without the mentioned permissions from point 1.
Workarounds
If updating Rancher to a patched version is not possible, then the following workarounds must be observed to mitigate this issue:
- Only grant Project Owner and Manage Project Members roles to trusted users.
- Minimize the creation of custom roles that contain the
escalate,*or write verbs (create,delete,patch,update) onprojectroletemplatebindingsresource, and only grant such custom roles to trusted users. - Minimize the number of users that have permissions to
create,patchandupdateroletemplates.
Patches
Patched versions include releases 2.5.17 and 2.6.10 and later versions. This issue is not present in Rancher 2.7 releases.
Detection
The following script was developed to list role template bindings that give written access to the affected resources listed above. It is highly recommended to run the script in your environment and review the list of identified roles and role template bindings for possible signs of exploitation of this issue. The script requires jq installed and a kubeconfig with access to Rancher local cluster; it can also be executed in Rancher's kubectl shell.
For more information
If you have any questions or comments about this advisory:
- Reach out to SUSE Rancher Security team for security related inquiries.
- Open an issue in Rancher repository.
- Verify our support matrix and product support lifecycle
Пакеты
github.com/rancher/rancher
>= 2.5.0, < 2.5.17
2.5.17
github.com/rancher/rancher
>= 2.6.0, < 2.6.10
2.6.10
Связанные уязвимости
A Improper Privilege Management vulnerability in SUSE Rancher, allows users with access to the escalate verb on PRTBs to escalate permissions for any -promoted resource in any cluster. This issue affects: SUSE Rancher Rancher versions prior to 2.5.17; Rancher versions prior to 2.6.10.