Headline
GHSA-64jq-m7rq-768h: Rancher's External RoleTemplates can lead to privilege escalation
Impact
A vulnerability has been identified whereby privilege escalation checks are not properly enforced for RoleTemplate
objects when external=true, which in specific scenarios can lead to privilege escalation.
The bug in the webhook rule resolver ignores rules from a ClusterRole
for external RoleTemplates
when its context is set to either project
or is left empty. The fix introduces a new field to the RoleTemplate
CRD named ExternalRules
. The new field will be used to resolve rules directly from the RoleTemplate
. Additionally, rules from the backing ClusterRole
will be used if ExternalRules
is not provided. The new field will always take precedence when it is set, and serve as the source of truth for rules used when creating Rancher resources on the local cluster.
Please note that this is a breaking change for external RoleTemplates
, when context is set to project
or empty and the backing ClusterRole
does not exist, as this was not previously required.
Important: The fix is automatically applied when upgrading to the release lines 2.8
and above. For users still on the 2.7
release line, after the upgrade to a patched version, users are required to opt-in to the fix by enabling the external-rules
feature flag.
Please consult the associated MITRE ATT&CK - Technique - Exploitation for Privilege Escalation for further information about this category of attack.
Patches
Patched versions include releases 2.7.14
and 2.8.5
.
Workarounds
The following script was developed for Rancher Manager administrators to identify RoleTemplates
impacted by this vulnerability. The script requires jq
installed and a kubeconfig
with access to Rancher local cluster; it can also be executed in Rancher’s kubectl shell.
#!/bin/bash
set -euo pipefail
# get all RoleTemplates with .context == "project" or .context == "" that don't have externalRules.
rts=$(kubectl get roletemplates -o json | jq -r '.items[] | select((.context == "project" or .context == "") and .external == true and .externalRules == null) | .metadata.name')
found_invalid_rt=false
for rt in $rts; do
if ! kubectl get clusterrole "$rt" > /dev/null 2>&1; then
echo "$rt" # prints RoleTemplate names that don't have a backing ClusterRole
found_invalid_rt=true
fi
done
if ! $found_invalid_rt ; then
echo 'This cluster is not affected by CVE-2023-32197: no RoleTemplate objects found'
fi
It will return all objects affected by this vulnerability. The administrator can fix those objects by creating the backing ClusterRole
that they refer to.
References
If you have any questions or comments about this advisory:
- Reach out to the SUSE Rancher Security team for security-related inquiries.
- Open an issue in the Rancher repository.
- Verify with our support matrix and product support lifecycle.
Impact
A vulnerability has been identified whereby privilege escalation checks are not properly enforced for RoleTemplateobjects when external=true, which in specific scenarios can lead to privilege escalation.
The bug in the webhook rule resolver ignores rules from a ClusterRole for external RoleTemplates when its context is set to either project or is left empty. The fix introduces a new field to the RoleTemplate CRD named ExternalRules. The new field will be used to resolve rules directly from the RoleTemplate. Additionally, rules from the backing ClusterRole will be used if ExternalRules is not provided. The new field will always take precedence when it is set, and serve as the source of truth for rules used when creating Rancher resources on the local cluster.
Please note that this is a breaking change for external RoleTemplates, when context is set to project or empty and the backing ClusterRole does not exist, as this was not previously required.
Important: The fix is automatically applied when upgrading to the release lines 2.8and above. For users still on the 2.7 release line, after the upgrade to a patched version, users are required to opt-in to the fix by enabling the external-rules feature flag.
Please consult the associated MITRE ATT&CK - Technique - Exploitation for Privilege Escalation for further information about this category of attack.
Patches
Patched versions include releases 2.7.14 and 2.8.5.
Workarounds
The following script was developed for Rancher Manager administrators to identify RoleTemplates impacted by this vulnerability. The script requires jq installed and a kubeconfig with access to Rancher local cluster; it can also be executed in Rancher’s kubectl shell.
#!/bin/bash set -euo pipefail
get all RoleTemplates with .context == “project” or .context == “” that don’t have externalRules.
rts=$(kubectl get roletemplates -o json | jq -r ‘.items[] | select((.context == “project” or .context == “”) and .external == true and .externalRules == null) | .metadata.name’) found_invalid_rt=false
for rt in $rts; do if ! kubectl get clusterrole “$rt” > /dev/null 2>&1; then echo “$rt” # prints RoleTemplate names that don’t have a backing ClusterRole found_invalid_rt=true fi done
if ! $found_invalid_rt ; then echo ‘This cluster is not affected by CVE-2023-32197: no RoleTemplate objects found’ fi
It will return all objects affected by this vulnerability. The administrator can fix those objects by creating the backing ClusterRole that they refer to.
References
- CVE-2023-32196
If you have any questions or comments about this advisory:
- Reach out to the SUSE Rancher Security team for security-related inquiries.
- Open an issue in the Rancher repository.
- Verify with our support matrix and product support lifecycle.
References
- GHSA-64jq-m7rq-768h