This page describes Kubernetes security posture scanning , a feature of the security posture dashboard that helps you proactively identify and address security vulnerabilities in your Google Kubernetes Engine (GKE) clusters. This page explains workload configuration auditing and security bulletin surfacing for finding and mitigating security risks in GKE.
This page is for Security specialists who monitor clusters for security issues. To learn more about common roles and example tasks that we reference in Google Cloud content, see Common GKE user roles and tasks .
To enable and use Kubernetes security posture scanning, see Automatically audit workloads for configuration issues
Kubernetes security posture scanning provides the following features:
Pricing
Offered at no extra charge in GKE.
Entries added to Cloud Logging are subject to Cloud Logging pricing .
About workload configuration auditing
The workloads that you deploy on GKE should have a hardened configuration that limits their attack surface. Checking workloads across clusters for configuration issues can be difficult to do manually at scale. You can use the security posture dashboard to automatically audit the configuration of all your running workloads across multiple clusters and return actionable, scored results and opinionated recommendations to improve your security posture.
Workload configuration auditing checks each deployed workload against a subset of policies in the Pod Security Standards . Workload configuration auditing happens on Google's infrastructure and doesn't use compute resources on your nodes.
Benefits of workload configuration auditing
- Automate detection of known configuration concerns across all workloads.
- Get actionable recommendations to improve security posture.
- Use the Google Cloud console to get a high-level view of configuration concerns.
- Use Logging to get an auditable trail of concerns for better reporting and observability.
How workload configuration auditing works
For each eligible deployed workload, GKE continuously scans the
workload's specification and compares the fields and values to the controls
defined in the underlying security policy. For example, a Pod with spec.containers.securityContext.privileged=true
violates the Baseline Pod
Security Standard, and a Pod with the spec.securityContext.runAsNonRoot
field
set to false
violates the Restricted standard. For a list of the security
policies that GKE checks, refer to What does workload configuration auditing check?
.
After scanning and discovering concerns, GKE rates the severity of discovered configuration issues based on the built-in security hardening measures. GKE assigns a severity rating that can inform the speed with which you respond to the concern. The Google Cloud console displays the results and recommended actions you can take to fix the concerns. GKE also adds entries to Cloud Logging for tracing and auditing.
What does workload configuration auditing check?
Host namespaces
Pods that share host namespaces allow Pod processes to communicate with host processes and gather host information, which could lead to a container escape.
-
spec.hostNetwork -
spec.hostIPC -
spec.hostPID
- Undefined or nil
-
false
Privileged containers
Privileged containers allow nearly unrestricted host access. They share namespaces with the host, and lack control group, seccomp, AppArmor, and capability restrictions.
-
spec.containers[*].securityContext.privileged -
spec.initContainers[*].securityContext.privileged -
spec.ephemeralContainers[*].securityContext.privileged
- Undefined or nil
-
false
Host port access
Exposing a host port to a container potentially allows the container to intercept network traffic to a host service using that port or to bypass network access control rules, such as the rules in a NetworkPolicy.
-
spec.containers[*].ports[*].hostPort -
spec.initContainers[*].ports[*].hostPort -
spec.ephemeralContainers[*].ports[*].hostPort
- Undefined or nil
-
0
Non-default capabilities
A container has assigned capabilities that could allow a container escape.
-
spec.containers[*].securityContext.capabilities.add -
spec.initContainers[*].securityContext.capabilities.add -
spec.ephemeralContainers[*].securityContext.capabilities.add
- Undefined or nil
-
AUDIT_WRITE -
CHOWN -
DAC_OVERRIDE -
FOWNER -
FSETID -
KILL -
MKNOD -
NET_BIND_SERVICE -
SETFCAP -
SETGID -
SETPCAP -
SETUID -
SYS_CHROOT
Mounting host path volumes
hostPath
volumes mount files or directories from the host. These
volumes present security risks that could lead to container escape.
spec.volumes[*].hostPath
Non-default /proc
mask
The default /proc
mount type masks certain paths in /proc
to avoid exposure of paths that could lead to information
leakage or container escape. Using a non-default type increases these risks.
-
spec.containers[*].securityContext.procMount -
spec.initContainers[*].securityContext.procMount -
spec.ephemeralContainers[*].securityContext.procMount
- Undefined or nil
- Default
Unsafe sysctls mask
A Pod can be configured to allow modification of unsafe kernel
parameters using the /proc/sys
virtual file system. Unsafe
parameters don't support namespacing, don't properly isolate their effect
between Pods, could harm the node's health, or might allow the Pod to gain
resources beyond its limits.
spec.securityContext.sysctls[*].name
- Undefined or nil
-
kernel.shm_rmid_forced -
net.ipv4.ip_local_port_range -
net.ipv4.ip_unprivileged_port_start -
net.ipv4.tcp_syncookies -
net.ipv4.ping_group_range
Running as non-root
You can explicitly allow a container to run as the root user if the runAsUser
or the USER
directive in the image
specifies the root user. The lack of preventive security controls when
running as the root user increases the risk of container escape.
-
spec.securityContext.runAsNonRoot -
spec.containers[*].securityContext.runAsNonRoot -
spec.initContainers[*].securityContext.runAsNonRoot -
spec.ephemeralContainers[*].securityContext.runAsNonRoot
true
Privilege escalation
A container can be explicitly configured to allow privilege escalation on execution. This permits a process created within the container by executing a set-user-id, set-group-id, or file capability executable to gain the privileges specified by the executable. The lack of preventive security control increases the risk of container escape.
-
spec.containers[*].securityContext.allowPrivilegeEscalation -
spec.initContainers[*].securityContext.allowPrivilegeEscalation -
spec.ephemeralContainers[*].securityContext.allowPrivilegeEscalation
false
Unconfined AppArmor profile
A container can be explicitly configured to be unconfined by AppArmor. This ensures that no AppArmor profile is applied to the container and is thus not constrained by them. The disabled preventive security control increases the risk of container escape.
metadata.annotations["container.apparmor.security.beta.kubernetes.io/*"]
false
Additionally, GKE checks for any RBAC RoleBindings or ClusterRoleBindings that reference one of the following users or groups:
-
system:anonymous -
system:authenticated -
system:unauthenticated
If any RBAC bindings that reference these users or groups exist, a finding named Effectively Anonymous Users Granted GKE Cluster Accesswith a severity of Mediumappears in the security posture dashboard. These users and groups are effectively anonymous and shouldn't be used in RoleBindings or ClusterRoleBindings. For more information, see Avoid default roles and groups .
About security bulletin surfacing
When a vulnerability is discovered in GKE, we patch the vulnerability and publish a security bulletin for the vulnerability. For information about identification, patching, and timelines, refer to GKE security patching .
The security posture dashboard displays security bulletins that affect your clusters, workloads, and Standard mode node pools. This feature is a part of the Kubernetes security posture capability of the security posture dashboard and is automatically enabled when you create an Autopilot or Standard cluster. To enable Kubernetes security posture scanning, use the instructions in Automatically audit workloads for configuration issues .
The Google Cloud console displays details such as affected clusters, versions, and recommended patch versions for upgrades to mitigate the vulnerability. You only see bulletins for which a mitigation is available in your cluster's Google Cloud region or zone.
To view bulletins for clusters that you enrolled in Kubernetes security posture scanning, go to the security posture dashboard:
Any available bulletins that affect your environment appear in the Security bulletinssection.
